Internet DRAFT - draft-ietf-lisp-ddt
draft-ietf-lisp-ddt
Network Working Group V. Fuller
Internet-Draft
Intended status: Experimental D. Lewis
Expires: July 22, 2017 V. Ermagan
Cisco Systems
A. Jain
Juniper Networks
A. Smirnov
Cisco Systems
January 18, 2017
LISP Delegated Database Tree
draft-ietf-lisp-ddt-09
Abstract
This document describes the LISP Delegated Database Tree (LISP-DDT),
a hierarchical, distributed database which embodies the delegation of
authority to provide mappings from LISP Endpoint Identifiers (EIDs)
to Routing Locators (RLOCs). It is a statically-defined distribution
of the EID namespace among a set of LISP-speaking servers, called DDT
nodes. Each DDT node is configured as "authoritative" for one or
more EID-prefixes, along with the set of RLOCs for Map Servers or
"child" DDT nodes to which more-specific EID-prefixes are delegated.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 22, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
Fuller, et al. Expires July 22, 2017 [Page 1]
Internet-Draft LISP Delegated Database Tree January 2017
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Definition of Terms . . . . . . . . . . . . . . . . . . . . . 5
4. Database organization . . . . . . . . . . . . . . . . . . . . 7
4.1. XEID prefixes . . . . . . . . . . . . . . . . . . . . . . 7
4.2. DDT database tree structure . . . . . . . . . . . . . . . 7
4.3. Configuring prefix delegation . . . . . . . . . . . . . . 8
4.3.1. The root DDT node . . . . . . . . . . . . . . . . . . 9
5. DDT Map-Request . . . . . . . . . . . . . . . . . . . . . . . 9
6. The Map-Referral message . . . . . . . . . . . . . . . . . . 10
6.1. Action codes . . . . . . . . . . . . . . . . . . . . . . 10
6.2. Referral set . . . . . . . . . . . . . . . . . . . . . . 11
6.3. Incomplete flag . . . . . . . . . . . . . . . . . . . . . 11
6.4. Map-Referral Message Format . . . . . . . . . . . . . . . 11
6.4.1. SIG section . . . . . . . . . . . . . . . . . . . . . 14
7. DDT network elements and their operation . . . . . . . . . . 15
7.1. DDT node . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1.1. Match of a delegated prefix (or sub-prefix) . . . . . 15
7.1.2. Missing delegation from an authoritative prefix . . . 16
7.2. DDT Map Server . . . . . . . . . . . . . . . . . . . . . 16
7.3. DDT client . . . . . . . . . . . . . . . . . . . . . . . 17
7.3.1. Queuing and sending DDT Map-Requests . . . . . . . . 17
7.3.2. Receiving and following referrals . . . . . . . . . . 18
7.3.3. Handling referral errors . . . . . . . . . . . . . . 20
7.3.4. Referral loop detection . . . . . . . . . . . . . . . 20
8. Pseudo Code and Decision Tree diagrams . . . . . . . . . . . 21
8.1. Map Resolver processing of ITR Map-Request . . . . . . . 21
8.1.1. Pseudo-code summary . . . . . . . . . . . . . . . . . 21
8.1.2. Decision tree diagram . . . . . . . . . . . . . . . . 21
8.2. Map Resolver processing of Map-Referral message . . . . . 22
8.2.1. Pseudo-code summary . . . . . . . . . . . . . . . . . 22
8.2.2. Decision tree diagram . . . . . . . . . . . . . . . . 24
8.3. DDT Node processing of DDT Map-Request message . . . . . 25
8.3.1. Pseudo-code summary . . . . . . . . . . . . . . . . . 25
8.3.2. Decision tree diagram . . . . . . . . . . . . . . . . 27
9. Example topology and request/referral following . . . . . . . 27
Fuller, et al. Expires July 22, 2017 [Page 2]
Internet-Draft LISP Delegated Database Tree January 2017
9.1. Lookup of 2001:db8:0103:1::1/128 . . . . . . . . . . . . 30
9.2. Lookup of 2001:db8:0501:8:4::1/128 . . . . . . . . . . . 31
9.3. Lookup of 2001:db8:0104:2::2/128 . . . . . . . . . . . . 32
9.4. Lookup of 2001:db8:0500:2:4::1/128 . . . . . . . . . . . 32
9.5. Lookup of 2001:db8:0500::1/128 (non-existent EID) . . . . 33
10. Securing the database and message exchanges . . . . . . . . . 34
10.1. XEID-prefix Delegation . . . . . . . . . . . . . . . . . 34
10.2. DDT node operation . . . . . . . . . . . . . . . . . . . 35
10.2.1. DDT public key revocation . . . . . . . . . . . . . 35
10.3. Map Server operation . . . . . . . . . . . . . . . . . . 36
10.4. Map Resolver operation . . . . . . . . . . . . . . . . . 36
11. Open Issues and Considerations . . . . . . . . . . . . . . . 37
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37
13. Security Considerations . . . . . . . . . . . . . . . . . . . 37
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 38
14.1. Normative References . . . . . . . . . . . . . . . . . . 38
14.2. Informative References . . . . . . . . . . . . . . . . . 38
Appendix A. Acknowledgments . . . . . . . . . . . . . . . . . . 39
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
LISP [RFC6830] specifies an architecture and mechanism for replacing
the addresses currently used by IP with two separate name spaces:
Endpoint Identifiers (EIDs), used end-to-end for terminating
transport-layer associations, and Routing Locators (RLOCs), which are
bound to topological location, and are used for routing and
forwarding through the Internet infrastructure.
[RFC6833] specifies an interface between database storing EID-to-RLOC
mappings and LISP devices which need this information for packet
forwarding. Internal organization of such database is out the scope
of [RFC6833]. Multiple architectures of the database have been
proposed, each having its advantages and disadvantages (see for
example [RFC6836] and [RFC6837]).
This document specifies architecture for database of LISP EID-to-RLOC
mappings with emphasis on high scalability. LISP-DDT is a
hierarchical distributed database, which embodies the delegation of
authority to provide mappings, i.e. its internal structure mirrors
the hierarchical delegation of address space. It also provides
delegation information to Map Resolvers, which use the information to
locate EID-to-RLOC mappings. A Map Resolver, which needs to locate a
given mapping, will follow a path through the tree-structured
database, contacting, one after another, the DDT nodes along that
path until it reaches the leaf DDT node(s) authoritative for the
mapping it is seeking.
Fuller, et al. Expires July 22, 2017 [Page 3]
Internet-Draft LISP Delegated Database Tree January 2017
LISP offers a general-purpose mechanism for mapping between EIDs and
RLOCs. In organizing a database of EID to RLOC mappings, this
specification extends the definition of the EID numbering space by
logically prepending and appending several fields for purposes of
defining the database index key: Database-ID (DBID, 16 bits),
Instance identifier (IID, 32-bits), Address Family Identifier (16
bits), and EID-prefix (variable, according to AFI value). The
resulting concatenation of these fields is termed an "Extended EID
prefix" or XEID-prefix.
LISP-DDT defines a new device type, the DDT node, that is configured
as authoritative for one or more XEID-prefixes. It also is
configured with the set of more-specific sub-prefixes that are
further delegated to other DDT nodes. To delegate a sub-prefix, the
"parent" DDT node is configured with the RLOCs of each child DDT node
that is authoritative for the sub-prefix. Each RLOC either points to
a DDT Map Server to which an Egress Tunnel Router (ETR) has
registered that sub-prefix or points to another DDT node in the
database tree that further delegates the sub-prefix. See [RFC6833]
for a description of the functionality of the Map Server and Map
Resolver. Note that the target of a delegation must always be an
RLOC (not an EID) to avoid any circular dependency.
To provide a mechanism for traversing the database tree, LISP-DDT
defines a new LISP message type, the Map-Referral, which is returned
to the sender of a Map-Request when the receiving DDT node can refer
the sender to another DDT node that has more detailed information.
See Section 6 for the definition of the Map-Referral message.
To find an EID-to-RLOC mapping, a LISP-DDT client, usually a DDT Map
Resolver, starts by sending an Encapsulated Map-Request to a
preconfigured DDT node RLOC. The DDT node responds with a Map-
Referral message that either indicates that it will find the
requested mapping to complete processing of the request or that the
DDT client should contact another DDT node that has more-specific
information; in the latter case, the DDT node then sends a new
Encapsulated Map-Request to the next DDT node and the process repeats
in an iterative manner.
Conceptually, this is similar to the way that a client of the Domain
Name System (DNS) follows referrals (DNS responses that contain only
NS records) from a series of DNS servers until it finds an answer.
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
Fuller, et al. Expires July 22, 2017 [Page 4]
Internet-Draft LISP Delegated Database Tree January 2017
3. Definition of Terms
Extended EID (XEID): a LISP EID extended with data uniquely
identifying address space to which it belongs, such as LISP
instance ID, Address Family etc. See Section 4.1 for detailed
description of XEID data.
XEID-prefix: Extended EID-prefix (XEID-prefix) is a LISP EID-prefix
prepended with XEID data. An XEID-prefix is used as a key index
into the DDT database. XEID prefixes are used to describe
database organization and are not seen as a single entity in
protocol messages, though messages contain individual fields
constituting XEID prefix.
DDT node: a network infrastructure component responsible for
specific XEID-prefix(es) and for delegation of more-specific sub-
prefixes to other DDT nodes.
DDT client: a network infrastructure component that sends DDT Map-
Request messages and implements the iterative following of Map-
Referral results. Typically, a DDT client will be a Map Resolver
(as defined by [RFC6833]), but it is also possible for an ITR to
implement DDT client functionality.
DDT Map Server: a DDT node that also implements Map Server
functionality (forwarding Map-Requests and/or returning Map-
Replies if offering proxy Map-Reply service) for a subset of its
delegated prefixes. Map Server functions including proxying Map-
Replies are described in [RFC6833].
DDT Map Server peers: list of all DDT Map Servers performing Map
Server functionality for the same prefix. If peers are configured
on a DDT Map Server then the latter will provide complete
information about the prefix in its Map-Replies; otherwise the Map
Server will mark returned reply as potentially incomplete.
DDT Map Resolver: a network infrastructure element which implements
both the DDT client functionality and Map Resolver functionality
as defined by [RFC6833]. DDT Map Resolver accepts Map-Requests
from ITRs, sends DDT Map-Requests to DDT nodes and implements
iterative following of Map-Referrals. Note that Map Resolvers do
not respond to clients which sent Map-Requests, they only ensure
that the Map-Request has been forwarded to a LISP device (ETR or
proxy Map-Server) which will provide authoritative response to the
original requestor. A DDT Map Resolver will typically maintain a
cache of previously received Map-Referral message results
containing RLOCs for DDT nodes responsible for XEID- prefixes of
interest (termed the "referral cache").
Fuller, et al. Expires July 22, 2017 [Page 5]
Internet-Draft LISP Delegated Database Tree January 2017
Encapsulated Map-Request: a LISP Map-Request carried within an
Encapsulated Control Message, which has an additional LISP header
prepended. Sent to UDP destination port 4342. The "outer"
addresses are globally-routable IP addresses, also known as RLOCs.
Used by an ITR when sending to a Map Resolver and by a Map Server
when forwarding a Map-Request to an ETR as documented in LISP-MS
[RFC6833].
DDT Map-Request: an Encapsulated Map-Request sent by a DDT client to
a DDT node. The "DDT-originated" flag is set in the encapsulation
header indicating that the DDT node should return Map-Referral
messages if the Map-Request EID matches a delegated XEID-prefix
known to the DDT node. Section 7.3.1 describes how DDT Map-
Requests are sent. Section 5 defines position of the "DDT-
originated" flag in the Encapsulated Control Message header.
Authoritative XEID-prefix: an XEID-prefix delegated to a DDT node
and for which the DDT node may provide further delegations of
more-specific sub-prefixes.
Map-Referral: a LISP message sent by a DDT node in response to a DDT
Map-Request for an XEID that matches a configured XEID-prefix
delegation. A non-negative Map-Referral includes a "referral", a
set of RLOCs for DDT nodes that have information about the more
specific XEID prefix covering requested XEID; a DDT client
"follows the referral" by sending another DDT Map-Request to one
of those RLOCs to obtain either an answer or another referral to
DDT nodes responsible for even more specific XEID-prefix. See
Section 7.1 and Section 7.3.2 for details on the sending and
processing of Map-Referral messages.
Negative Map-Referral: an answer from an authoritative DDT node that
there is no mapping for the requested XEID. Negative Map-Referral
is a Map-Referral sent in response to a DDT Map-Request that
matches an authoritative XEID-prefix but for which there is no
delegation configured (or no ETR registration if sent by a DDT
Map-Server).
Pending Request List: the set of outstanding requests for which a
DDT Map Resolver has received encapsulated Map-Requests from its
clients seeking EID-to-RLOC mapping for a XEID. Each entry in the
list contains additional state needed by the referral following
process, including the XEID, requestor(s) of the XEID (typically,
one or more ITRs), saved information about the last referral
received and followed (matching XEID-prefix, action code, RLOC
set, index of last RLOC queried in the RLOC set), and any LISP-SEC
information ([I-D.ietf-lisp-sec]) that was included in the DDT
client Map-Request. An entry in the list may be interchangeably
Fuller, et al. Expires July 22, 2017 [Page 6]
Internet-Draft LISP Delegated Database Tree January 2017
termed a "pending request list entry" or simply a "pending
request".
For definitions of other terms, notably Map-Request, Map-Reply,
Ingress Tunnel Router (ITR), Egress Tunnel Router (ETR), Map Server,
and Map Resolver, please consult the LISP specification [RFC6830] and
the LISP Mapping Service specification [RFC6833].
4. Database organization
4.1. XEID prefixes
DDT database is indexed by Extended EID-prefixes (XEID-prefixes).
XEID-prefix is LISP EID-prefix together with data extending it to
uniquely identify address space of the prefix. XEID-prefix is
composed as binary encoding of five fields, in order of significance:
DBID (16 bits), Instance Identifier (IID, 32 bits), Address Family
Identifier (AFI, 16 bits), and EID-prefix (variable, according to AFI
value). The fields are concatenated, with the most significant
fields as listed above.
DBID is LISP-DDT database ID, a 16-bit field provided to allow the
definition of multiple databases. In this version of DDT DBID MUST
always be set to zero. Other values of DBID are reserved for future
use.
Instance ID (IID) is 32-bit value describing context of EID prefix if
the latter is intended for use in an environment where addresses may
not be unique, such as on a Virtual Private Network where [RFC1918]
address space is used. See "Using Virtualization and Segmentation
with LISP" in [RFC6830] for more discussion of Instance IDs.
Encoding of the instance ID (IID) is specified by
[I-D.ietf-lisp-lcaf].
Address Family Identifier (AFI) is a 16-bit value defining syntax of
EID-prefix. AFI values are assigned by IANA ([AFI].
4.2. DDT database tree structure
LISP-DDT database of each DDT node is organised as a tree structure
that is indexed by XEID prefixes. Leaves of the database tree
describe delegation of authority between DDT nodes (see more on
delegation and information kept in the database entries in
Section 4.3).
DDT Map-Requests sent by the DDT client to DDT nodes always contain
specific values for DBID, IID and AFI; never a range or unspecified
Fuller, et al. Expires July 22, 2017 [Page 7]
Internet-Draft LISP Delegated Database Tree January 2017
value for any of these fields. Thus XEID prefix used as key for
search in the database tree will have length of at least 64 bits.
DDT node may, for example, be authoritative for a consecutive range
of 3-tuples (DBID, IID, AFI) and all associated EID prefixes; or only
for a specific EID prefix of a single 3-tuple. Thus XEID prefixes/
keys of the database tree leaves may have length less, equal or more
than 64 bits.
It is important to note that LISP-DDT does not store actual EID-to-
RLOC mappings; it is, rather, a distributed index that can be used to
find the devices (ETRs which registered their EIDs with DDT Map
Servers) that can be queried with LISP to obtain those mappings.
Changes to EID-to-RLOC mappings are made on the ETRs which define
them, not to any DDT node configuration. DDT node configuration
changes are only required when branches of the database hierarchy are
added, removed, or modified.
4.3. Configuring prefix delegation
Every DDT node is configured with one or more XEID-prefixes for which
it is authoritative along with a list of delegations of XEID-prefixes
to other DDT nodes. A DDT node is required to maintain a list of
delegations for all sub-prefixes of its authoritative XEID-prefixes;
it also may list "hints", which are prefixes that it knows about that
belong to its parents, to the root, or to any other point in the
XEID-prefix hierarchy. A delegation (or hint) consists of an XEID-
prefix, a set of RLOCs for DDT nodes that have more detailed
knowledge of the XEID-prefix, and accompanying security information
(for details of security infomation exchange and its use see
Section 10). Those RLOCs are returned in Map-Referral messages when
the DDT node receives a DDT Map-Request with an XEID that matches a
delegation. A DDT Map Server will also have a set of sub-prefixes
for which it accepts ETR mapping registrations and for which it will
forward (or answer, if it provides proxy Map-Reply service) Map-
Requests.
XEID prefix (or prefixes) for which DDT node is authoritative and
delegation of authority for sub-prefixes is provided as configuration
of the DDT node. Implementations will likely develop a language to
express this prefix authority and delegation. Since DDT
configuration is static (i.e. not exchanged between DDT nodes as part
of the protocol itself) such language is implementation-dependant and
is outside the scope of this specification.
Fuller, et al. Expires July 22, 2017 [Page 8]
Internet-Draft LISP Delegated Database Tree January 2017
4.3.1. The root DDT node
The root DDT node is the logical "top" of the distributed database
hierarchy. It is authoritative for all XEID prefixes, that is for
all valid 3-tuples (DBID, IID, AFI) and their EID prefixes. A DDT
Map-Request that matches no configured XEID-prefix will be referred
to the root node (see Section 8 for formal description of conditions
when DDT Request is forwarded to the root node). The root node in a
particular instantiation of LISP-DDT therefore MUST be configured
with delegations for at least all defined IIDs and AFIs.
5. DDT Map-Request
A DDT client (usualy a Map Resolver) uses LISP Encapsulated Control
Message (ECM) to send Map-Request to a DDT node. Format of the ECM
is defined by [RFC6830]. This specification adds to ECM flag "DDT-
originated".
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | IPv4 or IPv6 Header |
OH | (uses RLOC addresses) |
\ | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Source Port = xxxx | Dest Port = 4342 |
UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LH |Type=8 |S|D| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | IPv4 or IPv6 Header |
IH | (uses RLOC or EID addresses) |
\ | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Source Port = xxxx | Dest Port = yyyy |
UDP +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | UDP Length | UDP Checksum |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
LCM | LISP Control Message |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
D: The "DDT-originated" flag. It is set by a DDT client to indicate
that the receiver SHOULD return Map-Referral messages as
appropriate. Use of the flag is further described in
Section 7.3.1. This bit is allocated from LISP message header
bits marked as Reserved in [RFC6830].
Fuller, et al. Expires July 22, 2017 [Page 9]
Internet-Draft LISP Delegated Database Tree January 2017
6. The Map-Referral message
This specification defines a new LISP message, the Map-Referral. It
is sent by a DDT node to a DDT client in response to a DDT Map-
Request message. See Section 6.4 for a detailed layout of the Map-
Referral message fields.
The message consists of an action code along with delegation
information about the XEID-prefix that matches the requested XEID.
6.1. Action codes
The action codes are as follows:
NODE-REFERRAL (0): indicates that the replying DDT node has
delegated an XEID-prefix that matches the requested XEID to one or
more other DDT nodes. The Map-Referral message contains a "map-
record" with additional information, most significantly the set of
RLOCs to which the prefix has been delegated, that is used by a
DDT client to "follow" the referral.
MS-REFERRAL (1): indicates that the replying DDT node has delegated
an XEID-prefix that matches the requested XEID to one or more DDT
Map Servers. It contains the same additional information as a
NODE-REFERRAL, but is handled slightly differently by the
receiving DDT client (see Section 7.3.2).
MS-ACK (2): indicates that the replying DDT Map Server received a
DDT Map-Request that matches an authoritative XEID-prefix for
which it has one or more registered ETRs. This means that the
request has been forwarded to one of those ETRs to provide an
answer to the querying ITR.
MS-NOT-REGISTERED (3): indicates that the replying DDT Map Server
received a Map-Request for one of its configured XEID-prefixes
which has no ETRs registered.
DELEGATION-HOLE (4): indicates that the requested XEID matches a
non-delegated sub-prefix of the XEID space. This is a non-LISP
"hole", which has not been delegated to any DDT Map Server or ETR.
See Section 7.1.2 for details. Also sent by a DDT Map Server with
authoritative configuration covering the requested EID, but for
which no specific site ETR is configured.
NOT-AUTHORITATIVE (5): indicates that the replying DDT node received
a Map-Request for an XEID for which it is not authoritative and
has no configured matching hint referrals. This can occur if a
cached referral has become invalid due to a change in the database
Fuller, et al. Expires July 22, 2017 [Page 10]
Internet-Draft LISP Delegated Database Tree January 2017
hierarchy. However, if such a DDT node has a "hint" delegation
covering the requested EID, it MAY choose to return NODE-REFERRAL
or MS-REFERRAL as appropriate. When returning action code NOT-
AUTHORITATIVE DDT node MUST provide EID-prefix received in the
request and the TTL MUST be set to 0.
6.2. Referral set
For "positive" action codes (NODE-REFERRAL, MS-REFERRAL, MS-ACK), a
DDT node MUST include in the Map-Referral message a list of RLOCs for
DDT nodes that are authoritative for the XEID-prefix being returned;
a DDT client uses this information to contact one of those DDT nodes
as it "follows" a referral.
6.3. Incomplete flag
A DDT node sets the "Incomplete" flag in a Map-Referral message if
the Referral Set is incomplete; this is intended to prevent a DDT
client from caching a referral with incomplete information. A DDT
node MUST set the "incomplete" flag in the following cases:
o If it is setting action code MS-ACK or MS-NOT-REGISTERED but the
matching XEID-prefix is not flagged in configuration as
"complete". XEID-prefix configuration on DDT Mapping Server
SHOULD be marked as "complete" when configuration of the XEID-
prefix lists all "peer" DDT nodes that are also authoritative for
the same XEID-prefix or when it is known that local DDT node is
the only one authoritative for the XEID-prefix.
o If it is setting action code NOT-AUTHORITATIVE.
6.4. Map-Referral Message Format
Fuller, et al. Expires July 22, 2017 [Page 11]
Internet-Draft LISP Delegated Database Tree January 2017
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Type=6 | Reserved | Record Count |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Nonce . . . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| . . . Nonce |
+-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | Record TTL |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
R | Referral Count| EID mask-len | ACT |A|I| Reserved |
e +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
c |SigCnt | Map Version Number | EID-AFI |
o +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
r | EID-prefix ... |
d +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| /| Priority | Weight | M Priority | M Weight |
| R +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| e | Unused Flags |L|p|R| Loc-AFI |
| f +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| \| Locator ... |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ~ Sig section ~
+-> +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type: Type value 6 was reserved for future use in RFC6830, this
document allocates this value to identify Map-Referral messages.
ACT: The "action" field of the mapping record in a Map-Referral
message encodes one of the 6 action types: NODE-REFERRAL, MS-
REFERRAL, MS-ACK, MS-NOT-REGISTERED, DELEGATION-HOLE, NOT-
AUTHORITATIVE. See Section 6.1 for description of their meaning.
Incomplete: The "I" bit indicates that a DDT node's referral-set of
locators is incomplete and the receiver of this message SHOULD NOT
cache the referral. A DDT sets the "incomplete" flag, the TTL, and
the Action Type field as follows:
Fuller, et al. Expires July 22, 2017 [Page 12]
Internet-Draft LISP Delegated Database Tree January 2017
-------------------------------------------------------------------
Type (Action field) Incomplete Referral-set TTL values
-------------------------------------------------------------------
0 NODE-REFERRAL NO YES 1440
1 MS-REFERRAL NO YES 1440
2 MS-ACK * * 1440
3 MS-NOT-REGISTERED * * 1
4 DELEGATION-HOLE NO NO 15
5 NOT-AUTHORITATIVE YES NO 0
-------------------------------------------------------------------
*: The "Incomplete" flag setting on Map Server originated referral of
MS-ACK and MS-NOT-REGISTERED types depend on whether the Map
Server has the full peer Map Server configuration for the same
prefix and has encoded the information in the mapping record.
Incomplete bit is not set when the Map Server has encoded the
information, which means the referral-set includes all the RLOCs
of all Map Servers that serve the prefix. It MUST be set when
configuration of the Map Server does not flag matching prefix as
configured with the complete information about "peer" Map Servers
or when the Map Server does not return all configured locators.
Referral Count: number of RLOCs in the current Referral set, it is
equal to the number of Ref sections in the message.
SigCnt: Indicates the number of signatures (sig section) present in
the Record. If SigCnt is larger than 0, the signature information
captured in a sig section as described in Section 6.4.1 will be
appended to the end of the record. The number of sig sections at the
end of the Record MUST match the SigCnt. Note that bits occupied by
SigCnt were Reserved in Records embedded into messages defined by
[RFC6830] and were required to be set to zero.
Loc-AFI: AFI of the Locator field. If AFI value is different from
LCAF AFI, security keys are not included in the record. If AFI is
equal to the LCAF AFI, the contents of the LCAF depend on the Type
field of the LCAF. LCAF Type 11 is used to store security material
along with the AFI of the locator. DDT nodes and DDT Map Servers can
use this LCAF Type to include public keys associated with their Child
DDT nodes for a XEID-prefix referral record. LCAF types and formats
are defined in [I-D.ietf-lisp-lcaf].
Fuller, et al. Expires July 22, 2017 [Page 13]
Internet-Draft LISP Delegated Database Tree January 2017
Locator: RLOC of a DDT node the DDT client is being referred to.
Lenght of this variable-length field is determined by the Loc-AFI.
All other fields and their descriptions are equivalent to those in
the Map-Reply message, as defined in LISP [RFC6830]. Note, though,
that the set of RLOCs correspond to the DDT node to be queried as a
result of the referral not the RLOCs for an actual EID-to-RLOC
mapping.
6.4.1. SIG section
SigCnt counts the number of signature sections that appear at the end
of the Record. Format of the signature section is described below.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/| Original Record TTL |
/ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
/ | Signature Expiration |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
s | Signature Inception |
i +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
g | Key Tag | Sig Length |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ | Sig-Algorithm | Reserved | Reserved |
\ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
\ ~ Signature ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Original Record TTL: The original Record TTL for this record that is
covered by the signature. Record TTL is in minutes.
Signature Expiration and Inception: Specify the validity period for
the signature. The signature MUST NOT be used for authentication
prior to the inception date and MUST NOT be used for authentication
after the expiration date. Each field specifies a date and time in
the form of a 32-bit unsigned number of seconds elapsed since 1
January 1970 00:00:00 UTC, ignoring leap seconds, in network byte
order.
Key Tag: An identifier to specify which key is used for this
signature if more than one valid key exists for the signing DDT node.
Sig Length: The length of the Signature field in bytes.
Sig-Algorithm: The identifier of the cryptographic algorithm used for
the signature. Sig-Algorithm values defined in this specification
are listed in Table 1. Implementation conforming to this
Fuller, et al. Expires July 22, 2017 [Page 14]
Internet-Draft LISP Delegated Database Tree January 2017
specification MUST implement at least RSA-SHA256 for DDT signing.
Sig-Algorithm type 1 RSA-SHA1 is deprecated and SHOULD NOT be used.
+---------------+------------+-----------+------------+
| Sig-Algorithm | Name | Reference | Notes |
+---------------+------------+-----------+------------+
| 1 | RSA-SHA1 | [RFC3447] | DEPRECATED |
| | | | |
| 2 | RSA-SHA256 | [RFC3447] | MANDATORY |
+---------------+------------+-----------+------------+
Table 1: Sig-Algorithm Values
Reserved: This field MUST be set to 0 on transmit and MUST be ignored
on receipt.
Signature: Contains the cryptographic signature that covers the
entire referral record that this signature belongs to. The Record
TTL is set to Original Record TTL and the sig fields are Signature
field is set to zero for the purpose of computing the Signature.
7. DDT network elements and their operation
As described above, DDT introduces a new network element, the "DDT
node", extends the functionality of Map Servers and Map Resolvers to
send and receive Map-Referral messages. The operation of each of
these devices is described as follows.
7.1. DDT node
When a DDT node receives a DDT Map-Request, it compares the requested
XEID against its list of XEID-prefix delegations and its list of
authoritative XEID-prefixes and acts as follows:
7.1.1. Match of a delegated prefix (or sub-prefix)
If the requested XEID matches one of the DDT node's delegated
prefixes, then a Map-Referral message is returned with the matching
more-specific XEID-prefix and the set of RLOCs for the referral
target DDT nodes including associated security information (see
Section 10 for details on security). If at least one DDT node of the
delegation is known to be a DDT Map Server, then the Map-Referral
message SHOULD be sent with action code MS-REFERRAL to indicate to
the receiver that LISP-SEC information (if saved in the pending
request) SHOULD be included in the next DDT Map-Request; otherwise,
the action code NODE-REFERRAL SHOULD be used.
Fuller, et al. Expires July 22, 2017 [Page 15]
Internet-Draft LISP Delegated Database Tree January 2017
Note that a matched delegation does not have to be for a sub-prefix
of an authoritative prefix; in addition to being configured to
delegate sub-prefixes of an authoritative prefix, a DDT node may also
be configured with other XEID-prefixes for which it can provide
referrals to DDT nodes anywhere in the database hierarchy. This
capability to define "shortcut hints" is never required to be
configured, but may be a useful heuristic for reducing the number of
iterations needed to find an EID, particular for private network
deployments.
Referral hints, if used properly, may reduce number of referrals a
DDT client needs to follow to locate DDT Map Server authoritative for
XEID prefix being resolved. On the other hand, incorrect use of
hints may create circular dependencies between DDT nodes (or
"referral loops"). DDT client MUST be prepared to handle such
circular referrals. See Section 7.3.4 for discussion of referral
loops and measures DDT client must implement in order to detect
circular referrals and prevent infinite looping.
Another danger with use of hints is when DDT deployment spans
multiple administrative domains (i.e. different authorities manage
DDT nodes in the same DDT database). In this case operator managing
a DDT node may not be aware of the fact that the node is being
referred to by hints. Locator addresses in hints may become stale
when referred DDT nodes are taken out of service or change their
locator addresses.
7.1.2. Missing delegation from an authoritative prefix
If the requested XEID did not match a configured delegation but does
match an authoritative XEID-prefix, then the DDT node MUST return a
negative Map-Referral that uses the least-specific XEID-prefix that
does not match any XEID-prefix delegated by the DDT node. The action
code is set to DELEGATION-HOLE; this indicates that the XEID is not a
LISP destination.
If the requested XEID did not match either a configured delegation,
an authoritative XEID-prefix or a "hint", then negative Map-Referral
with action code NOT-AUTHORITATIVE MUST be returned.
7.2. DDT Map Server
When a DDT Map Server receives a DDT Map-Request, its operation is
similar to that of a DDT node with additional processing as follows:
o If the requested XEID matches a registered XEID-prefix, then the
Map-Request is forwarded to one of the destination ETR RLOCs (or
the Map Server sends a Map-Reply, if it is providing proxy Map-
Fuller, et al. Expires July 22, 2017 [Page 16]
Internet-Draft LISP Delegated Database Tree January 2017
Reply service) and a Map-Referral with the MS-ACK action MUST be
returned to the sender of the DDT Map-Request.
o If the requested XEID matches a configured XEID-prefix for which
no ETR registration has been received then a negative Map-Referral
with action code MS-NOT-REGISTERED MUST be returned to the sender
of the DDT Map-Request.
7.3. DDT client
A DDT client queries one or more DDT nodes and uses an iterative
process of following returned referrals until it receives one with
action code MS-ACK (or an error indication). MS-ACK indicates that
the Map-Request has been sent to a Map Server that will forward it to
an ETR that, in turn, will provide a Map-Reply to the locator address
in the Map-Request.
DDT client functionality will typically be implemented by DDT Map
Resolvers. Just as any other Map Resolver, a DDT Map Resolver
accepts Map-Requests from its clients (typically, ITRs) and ensures
that those Map-Requests are forwarded to the correct ETR, which
generates Map-Replies. Unlike a Map Resolver that uses the ALT
mapping system (see [RFC6836]), however, a DDT Map Resolver
implements a DDT client functionality to find the correct ETR to
answer a Map-Request; this requires a DDT Map Resolver to maintain
additional state: a Map-Referral cache and pending request list of
XEIDs that are going through the iterative referral process.
DDT client functionality may be implemented on ITRs. In this case
the DDT client will not receive Map-Request from another network
element; instead, equivalent information will be provided to the DDT
client by the means of programming interface.
7.3.1. Queuing and sending DDT Map-Requests
When a DDT client receives a request to resolve XEID (in case of DDT
Map Resolver this will be in the form of received encapsulated Map-
Request), it first performs a longest-match search for the XEID in
its referral cache. If no match is found or if a negative cache
entry is found, then the destination is not in the database; a
negative Map-Reply MUST be returned and no further processing is
performed by the DDT client.
If a match is found, the DDT client creates a pending request list
entry for the XEID and saves the original request (in case of DDT
Map-Resolved, original Map-Request minus the encapsulation header)
along with other information needed to track progress through the
iterative referral process; the "referral XEID-prefix" is also
Fuller, et al. Expires July 22, 2017 [Page 17]
Internet-Draft LISP Delegated Database Tree January 2017
initialized to indicate that no referral has yet been received. The
DDT client then creates a DDT Map-Request (which is an encapsulated
Map-Request with the "DDT-originated" flag set in the message header)
for the XEID but without any authentication data that may have been
included in the original request. It sends the DDT Map-Request to
one of the RLOCs in the chosen referral cache entry. The referral
cache is initially populated with one or more statically-configured
entries; additional entries are added when referrals are followed, as
described below. A DDT client is not absolutely required to cache
referrals, but it doing so decreases latency and reduces lookup
delays.
Note that in normal use on the public Internet, the statically-
configured initial referral cache for a DDT client should include a
"default" entry with RLOCs for either the DDT root node or one or
more DDT nodes that contain hints for the DDT root node. If a DDT
client does not have such configuration, it will return a Negative
Map-Reply if it receives a query for an EID outside the subset of the
mapping database known to it. While this may be desirable on private
network deployments or during early transition to LISP when few sites
are using it, this behavior is not appropriate when LISP is in
general use on the Internet. If DDT message exchange is
authenticated as described in Section 10 then DDT client MUST also be
configured with public keys of DDT nodes pointed to by the "default"
cache entry. In this case the "default" entry will typically be for
the DDT root node.
7.3.2. Receiving and following referrals
After sending a DDT Map-Request, a DDT client expects to receive a
Map-Referral response. If none occurs within the timeout period, the
DDT client retransmits the request, sending to the next RLOC in the
referral cache entry if one is available. If all RLOCs have been
tried and the maximum number of retransmissions has occurred for
each, then the pending request list entry is dequeued and discarded.
In this case DDT client returns no response to sender of the original
request.
A DDT client processes a received Map-Referral message according to
each action code:
NODE-REFERRAL: The DDT client checks for a possible referral loop as
as described in Section 7.3.4. If no loop is found, the DDT
client saves the prefix returned in the Map-Referral message in
the referral cache, updates the saved prefix and saved RLOCs in
the pending request list entry, and follows the referral by
sending a new DDT Map-Request to one of the DDT node RLOCs listed
Fuller, et al. Expires July 22, 2017 [Page 18]
Internet-Draft LISP Delegated Database Tree January 2017
in the Referral Set; security information saved with the original
Map-Request SHOULD NOT be included.
MS-REFERRAL: The DDT client processes an MS-REFERRAL in the same
manner as a NODE-REFERRAL except that security information saved
with the original Map-Request MUST be included in the new Map-
Request sent to a Map Server (see Section 10 for details on
security).
MS-ACK: This is returned by a DDT Map Server to indicate that it has
one or more registered ETRs that can answer a Map-Request for the
XEID and the request has been forwarded to one of them (or if the
Map Server is doing proxy service for the prefix then reply has
been sent to the querying ITR). If the pending request did not
include saved LISP-SEC information or if that information was
already included in the previous DDT Map-Request (sent by the DDT
client in response to either an MS-REFERRAL or a previous MS-ACK
referral), then the pending request for the XEID is complete;
processing of the request stops and all request state can be
discarded. Otherwise, LISP-SEC information is required and has
not yet been sent to the authoritative DDT Map-Server; the DDT
client MUST re-send the DDT Map-Request with LISP-SEC information
included and the pending request queue entry remains until another
Map-Referral with MS-ACK action code is received. If the
"incomplete" flag is not set, the prefix is saved in the referral
cache.
MS-NOT-REGISTERED: The DDT Map Server queried could not process the
request because it did not have any ETRs registered for a
matching, authoritative XEID-prefix. If the DDT client has not
yet tried all of the RLOCs saved with the pending request, then it
sends a Map-Request to the next RLOC in that list. If all RLOCs
have been tried, then the destination XEID is not registered and
is unreachable. The DDT client MUST return a negative Map-Reply
to the requester (in case of DDT Map Resolver to the sender of
original Map-Request); this Map-Reply contains the least-specific
XEID-prefix in the range for which this DDT Map Server is
autoritative and no registrations exist and whose TTL value SHOULD
be set to one minute. A negative referral cache entry is created
for the prefix (whose TTL also SHOULD be set to one minute) and
processing of the request stops.
DELEGATION-HOLE: The DDT Map Server queried did not have an XEID-
prefix defined that matched the requested XEID so it does not
exist in the mapping database. The DDT client MUST return a
negative Map-Reply to the requester (in case of DDT Map Resolver
to the sender of original Map-Request); this Map-Reply SHOULD
indicate the least-specific XEID-prefix matching the requested
Fuller, et al. Expires July 22, 2017 [Page 19]
Internet-Draft LISP Delegated Database Tree January 2017
XEID for which no delegations exist and SHOULD have a TTL value of
15 minutes. A negative referral cache entry is created for the
prefix (which also SHOULD have TTL of 15 minutes) and processing
of the pending request stops.
NOT-AUTHORITATIVE: The DDT Map Server queried is not authoritative
for the requested XEID. This can occur if a cached referral has
become invalid due to a change in the database hierarchy. If the
DDT client receiving this message can determine that it is using
old cached information, it MAY choose to delete that cached
information and re-try the original Map-Request, starting from its
"root" cache entry. If this action code is received in response
to a query that did not use a cached referral information, then it
indicates a database synchronization problem or configuration
error. The pending request is silently discarded, i.e. all state
for the request that caused this answer is removed and no answer
is returned to the original requestor.
7.3.3. Handling referral errors
Other states are possible, such as a misconfigured DDT node (acting
as a proxy Map Server, for example) returning a Map-Reply to the DDT
client; they should be considered errors and logged as such. It is
not clear exactly what else the DDT client should do in such cases;
one possibility is to remove the pending request list entry and send
a negative Map-Reply to the requester (in case of DDT Map Resolver to
the sender of original Map-Request). Alternatively, if a DDT client
detects unexpected behavior by a DDT node, it could mark that node as
unusable in its referral cache and update the pending request to try
a different DDT node if more than one is listed in the referral
cache. In any case, any prefix contained in a Map-Referral message
that causes a referral error (including a referral loop) is not saved
in the DDT client referral cache.
7.3.4. Referral loop detection
In response to a Map-Referral message with action code NODE-REFERRAL
or MS-REFERRAL, a DDT client is directed to query a new set of DDT
node RLOCs that are expected to have more-specific XEID-prefix
information for the requested XEID. To prevent a possible "iteration
loop" (following referrals back-and-forth among a set of DDT nodes
without ever finding an answer), a DDT client saves the last received
referral XEID-prefix for each pending request and checks that a newly
received NODE-REFERRAL or MS-REFERRAL message contains a more-
specific referral XEID-prefix; an exact or less-specific match of the
saved XEID-prefix indicates a referral loop. If a loop is detected,
the DDT Map Resolver handles the request as described in
Section 7.3.3. Otherwise, the DDT client saves the most recently
Fuller, et al. Expires July 22, 2017 [Page 20]
Internet-Draft LISP Delegated Database Tree January 2017
received referral XEID-prefix with the pending request when it
follows the referral.
As an extra measure to prevent referral loops, it is probably also
wise to limit the total number of referrals for any request to some
reasonable number; the exact value of that number will be determined
during experimental deployment of LISP-DDT, but is bounded by the
maximum length of the XEID.
Note that when a DDT client adds an entry to its lookup queue and
sends an initial Map-Request for an XEID, the queue entry has no
previous referral XEID-prefix; this means that the first DDT node
contacted by a DDT Map Resolver may provide a referral to anywhere in
the DDT hierarchy. This, in turn, allows a DDT client to use
essentially any DDT node RLOCs for its initial cache entries and
depend on the initial referral to provide a good starting point for
Map-Requests; there is no need to configure the same set of root DDT
nodes on all DDT clients.
8. Pseudo Code and Decision Tree diagrams
To illustrate DDT algorithms described above and to aid in
implementation, each of the major DDT Map Server and DDT Map Resolver
functions are described below, first using simple "psuedo-code" and
then in the form of a decision tree.
8.1. Map Resolver processing of ITR Map-Request
8.1.1. Pseudo-code summary
if ( request pending i.e., (ITR,EID) of request same ) {
replace old request with new & use new request nonce
for future requests
} else if ( no match in refcache ) {
return negative map-reply to ITR
} else if ( match type delegation hole ) {
return negative map-reply to ITR
} else if ( match type ms-ack ) {
fwd DDT request to map-server
} else {
store & fwd DDT request w/o security material to node delegation
}
8.1.2. Decision tree diagram
Fuller, et al. Expires July 22, 2017 [Page 21]
Internet-Draft LISP Delegated Database Tree January 2017
+------------+
| Is Request | Yes
| |----> Replace old request with
| Pending? | new nonce for future requests
+------------+
|
|No
|
V
+------------+
| Match In | No
| Referral |----> Send Negative Map-Reply
| cache? | (not a likely event as root or
+------------+ hint configured on every MR)
|
|Yes
|
V
+------------+
| Match Type | Yes
| Delegation |----> Send Negative Map-Reply
| Hole? |
+------------+
|
|No
|
V
+------------+
| Match Type | Yes
| MS-ACK? |----> Forward DDT Map-request to Map-Server
| |
+------------+
|
|No
|
V
Store request & Fwd DDT Request w/o security material
to DDT node delegation
8.2. Map Resolver processing of Map-Referral message
8.2.1. Pseudo-code summary
if ( authentication signature validation failed ) {
silently drop
}
if ( no request pending matched by referral nonce ) {
Fuller, et al. Expires July 22, 2017 [Page 22]
Internet-Draft LISP Delegated Database Tree January 2017
silently drop
}
if ( pfx in referral less specific than last referral used ) {
if ( gone through root ) {
silently drop
} else {
send request to root
}
}
switch (map_referral_type) {
case NOT_AUTHORITATIVE :
if ( gone through root ) {
return negative map-reply to ITR
} else {
send request to root
}
case DELEGATION_HOLE:
cache & send negative map-reply to ITR
case MS_REFERRAL:
if ( referral equal to last used ) {
if ( gone through root ) {
return negative map-reply to ITR
} else {
send request to root
}
} else {
cache
follow the referral, include security material
}
case NODE_REFERRAL:
if ( referral equal to last used ) {
if ( gone through root ) {
return negative map-reply to ITR
} else {
send request to root
}
} else {
cache
follow the referral, strip security material
}
case MS_ACK:
Fuller, et al. Expires July 22, 2017 [Page 23]
Internet-Draft LISP Delegated Database Tree January 2017
if ( security material stripped ) {
resend request with security material
if { !incomplete } {
cache
}
}
case MS_NOT_REGISTERED:
if { all map-server delegations not tried } {
follow delegations not tried
if ( !incomplete ) {
cache
}
} else {
send negative map-reply to ITR
if { !incomplete } {
cache
}
}
case DEFAULT:
drop
}
}
8.2.2. Decision tree diagram
+----------------+
| Auth Signature | No
| Valid? |----> Silently drop
+----------------+
| Yes
V
+------------+
| Is Request | No
| Pending? |----> Silently drop
+------------+
| Yes
V
+------------------------------+ Yes
| Pfx less specific than last? |----> Silently drop
+------------------------------+
|No
V
+---------------------------------------------------+
| What is Map-Referral Type? |--UNKNOWN-+
+---------------------------------------------------+ |
| | | | | | V
Fuller, et al. Expires July 22, 2017 [Page 24]
Internet-Draft LISP Delegated Database Tree January 2017
| | | | | DEL_HOLE DROP
| | | | MS_ACK |
| | | | | V
| | MS_REF NODE_REF | Cache & return
| | | | V negative map-reply
| | | | +---------+
| NOT_AUTH | | | Was sec | Yes
| | | | | material|
| | | | |Stripped?|----> Done
| | V V +---------+
| | +------------+ | No
| | Yes | Pfx equal | V
MS_NOT_REGISTERED | +---| to last | +------------+
| | | | used? | | Incomplete | Yes
| | | +------------+ | bit set? |---> Resend DDT
| V V |No +------------+ request w
| +------------+ | |No security
| | Gone | V | material
| | Through | Cache & follow V
| | Root? | the referral Cache & resend DDT
| +------------+ request with
| |No |Yes security material
| | |
| V V
| Send req Send negative map-reply
| to root
V
+-----------+ Yes +-----------+ Yes
| Other MS |----Follow other MS-------->|Incomplete |----> Don't cache
| not tried?| |bit set? |
| |---Send negative map-reply->| |----> Cache
+-----------+ No +-----------+ No
8.3. DDT Node processing of DDT Map-Request message
8.3.1. Pseudo-code summary
Fuller, et al. Expires July 22, 2017 [Page 25]
Internet-Draft LISP Delegated Database Tree January 2017
if ( I am not authoritative ) {
send map-referral NOT_AUTHORITATIVE with
incomplete bit set and ttl 0
} else if ( delegation exists ) {
if ( delegated map-servers ) {
send map-referral MS_REFERRAL with
ttl 'Default_DdtNode_Ttl'
} else {
send map-referral NODE_REFERRAL with
ttl 'Default_DdtNode_Ttl'
}
} else {
if ( eid in site) {
if ( site registered ) {
forward map-request to etr
if ( map-server peers configured ) {
send map-referral MS_ACK with
ttl 'Default_Registered_Ttl'
} else {
send map-referral MS_ACK with
ttl 'Default_Registered_Ttl' and incomplete bit set
}
} else {
if ( map-server peers configured ) {
send map-referral MS_NOT_REGISTERED with
ttl 'Default_Configured_Not_Registered_Ttl'
} else {
send map-referral MS_NOT_REGISTERED with
ttl 'Default_Configured_Not_Registered_Ttl'
and incomplete bit set
}
}
} else {
send map-referral DELEGATION_HOLE with
ttl 'Default_Negative_Referral_Ttl'
}
}
where architectural constants for TTL are set as follows:
Default_DdtNode_Ttl 1440 minutes
Default_Registered_Ttl 1440 minutes
Default_Negative_Referral_Ttl 15 minutes
Default_Configured_Not_Registered_Ttl 1 minute
Fuller, et al. Expires July 22, 2017 [Page 26]
Internet-Draft LISP Delegated Database Tree January 2017
8.3.2. Decision tree diagram
+------------+
| Am I | No
| Authori- |----> Return NOT_AUTHORITATIVE
| tative? | Incomplete = 1
+------------+ ttl = Default_DdtNode_Ttl
|
|Yes
|
V
+------------+ +------------+
| Delegation | Yes | Delegations| Yes
| Exists? |---->| are map |----> Return MS_REFERRAL
| | | servers? | ttl = Default_DdtNode_Ttl
+------------+ +------------+
| \ No
|No +--> Return NODE_REFERRAL
| ttl = Default_DdtNode_Ttl
V
+------------+ +------------+ +------------+
| EID in | Yes | Site | Yes | Map-server |
| Site |---->| Registered?|----> Forward---->| peers |
| Config? | | | Map-request | configured?|
+------------+ +------------+ to ETR +------------+
| | | |
| |No No| |Yes
| | | |
| | V V
| | Return MS_ACK Return MS_ACK
| V with INC=1
| +------------+ ttl=Default_Registered_Ttl
| | Map-server | Yes
| | peers |----> Return MS_NOT_REGISTERED
| | configured?| ttl = Default_Negative_Referral_Ttl
| +------------+
| \ No
|No +--> Return MS_NOT_REGISTERED
| Incomplete = 1
V ttl = Default_Negative_Referral_Ttl
Return DELEGATION_HOLE
ttl = Default_Negative_Referral_Ttl
9. Example topology and request/referral following
This chapter shows example DDT tree and several possible scenarios of
Map-Requests coming to a Map Resolver and subsequent iterative DDT
referrals. For the sake of example RLOCs of DDT nodes are shown in
Fuller, et al. Expires July 22, 2017 [Page 27]
Internet-Draft LISP Delegated Database Tree January 2017
IPv4 address space while the EIDs are in IPv6 AF. The same principle
of hierarchical delegation and pinpointing referrals is equally
applicable to any AF whose address hierarchy can be expressed as a
bitstring with associated length. DDT tree of IPv4 prefixes is
another AF with immediate practical value.
To show how referrals are followed to find the RLOCs for a number of
EIDs, consider the following example EID topology for DBID=0, IID=0,
AFI=2, and EID=0/0
Fuller, et al. Expires July 22, 2017 [Page 28]
Internet-Draft LISP Delegated Database Tree January 2017
+---------------------+ +---------------------+
| root1: 192.0.2.1 | | root2: 192.0.2.2 |
| authoritative: ::/0 | | authoritative: ::/0 |
+---------------------+ +---------------------+
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| | | |
V V V V
+-------------------------+ +--------------------------+
| DDT node1: 192.0.2.11 | | DDT node2: 192.0.2.12 |
| authoritative: | | authoritative: |
| 2001:db8::/32 | | 2001:db8::/32 |
+-------------------------+ +--------------------------+
| \ / |
| \ / |
| X |
| / \ |
| / \ |
| | | |
V V V V
+--------------------------+ +---------------------------+
| Map-Server1: 192.0.2.101 | | DDT node3: 192.0.2.201 |
| authoritative: | | authoritative: |
| 2001:db8:0100::/40 | | 2001:db8:0500::/40 |
| site1: 2001:db8:0103::/48| +---------------------------+
| site2: 2001:db8:0104::/48| | |
+--------------------------+ | |
| |
| |
V V
+---------------------------+ +---------------------------+
| Map-Server2: 192.0.2.211 | | Map-Server3: 192.0.2.221 |
| authoritative: | | authoritative: |
| 2001:db8:0500::/48 | | 2001:db8:0501::/48 |
|site3: 2001:db8:0500:1::/64| |site5: 2001:db8:0501:8::/64|
|site4: 2001:db8:0500:2::/64| |site6: 2001:db8:0501:9::/64|
+---------------------------+ +---------------------------+
DDT nodes are configured for this "root" at IP addresses 192.0.2.1
and 192.0.2.2. DDT Map Resolvers are configured with default
referral cache entries to these addresses.
The root DDT nodes delegate 2001:db8::/32 to two DDT nodes with IP
addresses 192.0.2.11 and 192.0.2.12.
Fuller, et al. Expires July 22, 2017 [Page 29]
Internet-Draft LISP Delegated Database Tree January 2017
The DDT nodes for 2001:db8::/32 delegate 2001:db8:0100::/40 to a DDT
Map Server with RLOC 192.0.2.101
The DDT Map Server for 2001:db8:0100::/40 is configured to allow ETRs
to register the sub-prefixes 2001:db8:0103::/48 and
2001:db8:0104::/48
The DDT nodes for 2001:db8::/32 also delegate 2001:db8:0500::/40 to a
DDT node with RLOC 192.0.2.201
The DDT node for 2001:db8:0500::/40 is further configured to delegate
2001:db8:0500::/48 to a DDT Map Server with RLOC 192.0.2.211 and
2001:db8:0501::/48 to a DDT Map Server with RLOC 192.0.2.221
The DDT Map Server for 2001:db8:0500::/48 is configured to allow ETRs
to register the sub-prefixes 2001:db8:0500:1::/64 and
2001:db8:0500:2::/64
The DDT Map Server for 2001:db8:0501::/48 is configured to allow ETRs
to register the sub-prefixes 2001:db8:0501:8::/64 and
2001:db8:0501:9::/64
9.1. Lookup of 2001:db8:0103:1::1/128
The first example shows a DDT Map Resolver following a delegation
from the root to a DDT node followed by another delegation to a DDT
Map Server.
ITR1 sends an Encapsulated Map-Request for 2001:db8:0103:1::1 to one
of its configured (DDT) Map Resolvers. The DDT Map Resolver proceeds
as follows:
1. Send DDT Map-Request (for 2001:db8:0103:1::1) to one of the root
DDT nodes, 192.0.2.1 or 192.0.2.2
2. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8::/32, action code NODE-REFERRAL, RLOC set (192.0.2.11,
192.0.2.12)
3. Send DDT Map-Request to 192.0.2.11 or 192.0.2.12
4. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8:0100::/40, action code MS-REFERRAL, RLOC set
(192.0.2.101)
5. Send DDT Map-Request to 192.0.2.101; if the ITR-originated
Encapsulated Map-Request had a LISP-SEC signature, it is included
Fuller, et al. Expires July 22, 2017 [Page 30]
Internet-Draft LISP Delegated Database Tree January 2017
6. DDT Map Server at 192.0.2.101 decapsulates the DDT Map-Request
and forwards to a registered site1 ETR for 2001:db8:0103::/48
7. DDT Map Server at 192.0.2.101 sends a Map-Referral message for
EID-prefix 2001:db8:0103::/48, action code MS-ACK to the DDT Map
Resolver
8. DDT Map Resolver receives Map-Referral message and dequeues the
pending request for 2001:db8:0103:1::1
9. site1 ETR for 2001:db8:0103::/48 receives Map-Request forwarded
by DDT Map Server and sends Map-Reply to ITR1
9.2. Lookup of 2001:db8:0501:8:4::1/128
The next example shows a three-level delegation: root to first DDT
node, first DDT node to second DDT node, second DDT node to DDT Map
Server.
ITR2 sends an Encapsulated Map-Request for 2001:db8:0501:8:4::1 to
one of its configured (DDT) Map Resolvers, which are different from
those for ITR1. The DDT Map Resolver proceeds as follows:
1. Send DDT Map-Request (for 2001:db8:0501:8:4::1) to one of the
root DDT nodes, 192.0.2.1 or 192.0.2.2
2. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8::/32, action code NODE-REFERRAL, RLOC set (192.0.2.11,
192.0.2.12)
3. Send DDT Map-Request to 192.0.2.11 or 192.0.2.12
4. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8:0500::/40, action code NODE-REFERRAL, RLOC set
(192.0.2.201)
5. Send DDT Map-Request to 192.0.2.201
6. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8:0501::/48, action code MS-REFERRAL, RLOC set
(192.0.2.221)
7. Send DDT Map-Request to 192.0.2.221; if the ITR-originated
Encapsulated Map-Request had a LISP-SEC signature, it is
included
8. DDT Map Server at 192.0.2.221 decapsulates the DDT Map-Request
and forwards to a registered site5 ETR for 2001:db8:0501:8::/64
Fuller, et al. Expires July 22, 2017 [Page 31]
Internet-Draft LISP Delegated Database Tree January 2017
9. DDT Map Server at 192.0.2.221 sends a Map-Referral message for
EID-prefix 2001:db8:0501:8::/64, action code MS-ACK, to the DDT
Map Resolver
10. DDT Map Resolver receives Map-Referral(MS-ACK) message and
dequeues the pending request for 2001:db8:0501:8:4::1
11. site5 ETR for 2001:db8:0501:8::/64 receives Map-Request
forwarded by DDT Map Server and sends Map-Reply to ITR2
9.3. Lookup of 2001:db8:0104:2::2/128
This example shows how a DDT Map Resolver uses a saved referral cache
entry to skip the referral process and go directly to a DDT Map
Server for a prefix that is similar to one previously requested.
In this case, ITR1 uses the same Map Resolver used in example
Section 9.1. It sends an Encapsulated Map-Request for
2001:db8:0104:2::2 to that (DDT) Map Resolver. The DDT Map-Resolver
finds an MS-REFERRAL cache entry for 2001:db8:0100::/40 with RLOC set
(192.0.2.101) and proceeds as follows:
1. Send DDT Map-Request (for 2001:db8:0104:2::2) to 192.0.2.101; if
the ITR-originated Encapsulated Map-Request had a LISP-SEC
signature, it is included
2. DDT Map Server at 192.0.2.101 decapsulates the DDT Map-Request
and forwards to a registered site2 ETR for 2001:db8:0104::/48
3. DDT Map Server at 192.0.2.101 sends a Map-Referral message for
EID-prefix 2001:db8:0104::/48, action code MS-ACK to the DDT Map
Resolver
4. DDT Map Resolver receives Map-Referral(MS-ACK) and dequeues the
pending request for 2001:db8:0104:2::2
5. site2 ETR for 2001:db8:0104::/48 receives Map-Request and sends
Map-Reply to ITR1
9.4. Lookup of 2001:db8:0500:2:4::1/128
This example shows how a DDT Map Resolver uses a saved referral cache
entry to start the referral process at a non-root, intermediate DDT
node for a prefix that is similar to one previously requested.
In this case, ITR2 asks the same Map Resolver used in example
Section 9.2. It sends an Encapsulated Map-Request for
2001:db8:0500:2:4::1 to that (DDT) Map Resolver, which finds a NODE-
Fuller, et al. Expires July 22, 2017 [Page 32]
Internet-Draft LISP Delegated Database Tree January 2017
REFERRAL cache entry for 2001:db8:0500::/40 with RLOC set
(192.0.2.201). It proceeds as follows:
1. Send DDT Map-Request (for 2001:db8:0500:2:4::1) to 192.0.2.201
2. Receive (and save in referral cache) Map-Referral for EID-prefix
2001:db8:0500::/48, action code MS-REFERRAL, RLOC set
(192.0.2.211)
3. Send DDT Map-Request to 192.0.2.211; if the ITR-originated
Encapsulated Map-Request had a LISP-SEC signature, it is included
4. DDT Map Server at 192.0.2.211 decapsulates the DDT Map-Request
and forwards to a registered site4 ETR for 2001:db8:0500:2::/64
5. DDT Map Server at 192.0.2.211 sends a Map-Referral message for
EID-prefix 2001:db8:0500:2::/64, action code MS-ACK to the DDT
Map Resolver
6. DDT Map Resolver receives Map-Referral(MS-ACK) and dequeues the
pending request for 2001:db8:0500:2:4::1
7. site4 ETR for 2001:db8:0500:2::/64 receives Map-Request and sends
Map-Reply to ITR2
9.5. Lookup of 2001:db8:0500::1/128 (non-existent EID)
This example uses the cached MS-REFERRAL for 2001:db8:0500::/48
learned above to start the lookup process at the DDT Map-Server at
192.0.2.211. The DDT Map Resolver proceeds as follows:
1. Send DDT Map-Request (for 2001:db8:0500::1) to 192.0.2.211; if
the ITR-originated Encapsulated Map-Request had a LISP-SEC
signature, it is included
2. DDT Map Server at 192.0.2.211, which is authoritative for
2001:db8:0500::/48, does not have a matching delegation for
2001:db8:0500::1. It responds with a Map-Referral message for
2001:db8:0500::/64, action code DELEGATION-HOLE to the DDT Map
Resolver. The prefix 2001:db8:0500::/64 is used because it is
the least-specific prefix that does match the requested EID, but
does not match one of configured delegations
(2001:db8:0500:1::/64 and 2001:db8:0500:2::/64).
3. DDT Map Resolver receives the delegation, adds a negative
referral cache entry for 2001:db8:0500::/64, dequeues the pending
request for 2001:db8:0500::1, and returns a negative Map-Reply to
ITR2.
Fuller, et al. Expires July 22, 2017 [Page 33]
Internet-Draft LISP Delegated Database Tree January 2017
10. Securing the database and message exchanges
This section specifies the DDT security architecture that provides
data origin authentication, data integrity protection, and XEID-
prefix delegation. Global XEID-prefix authorization is out of the
scope of this document.
Each DDT node is configured with one or more public/private key
pair(s) that are used to digitally sign referral records for XEID-
prefix(es) that the DDT node is authoritative for. In other words,
each public/private key pair is associated with the combination of a
DDT node and a XEID-prefix that it is authoritative for. Every DDT
node is also configured with the public keys of its children DDT
nodes. By including public keys of target child DDT nodes in the
Map-Referral records, and signing each record with the DDT node's
private key, a DDT node can securely delegate sub-prefixes of its
authoritative XEID-prefixes to its children DDT nodes. A DDT node
configured to provide hints must also have the public keys of the DDT
nodes that its hints point to. DDT node keys can be encoded using
LCAF type 11 to associate the key to the RLOC of the referred DDT
node. If a node has more than one public key, it should sign its
records with at least one of these keys. When a node has N keys, it
can sustain up to N-1 key compromises. Revocation mechanism is
described in Section 10.2.1.
Map Resolvers are configured with one or more trusted public keys
referred to as trust anchors. Trust anchors are used to authenticate
the DDT security infrastructure. Map Resolvers can discover a DDT
node's public key either by having it configured as a trust anchor,
or by obtaining it from the node's parent as part of a signed Map-
Referral. When a public key is obtained from a node's parent, it is
considered trusted if it is signed by a trust anchor, or if it is
signed by a key that was previously trusted. Typically, in a Map
Resolver, the root DDT node public keys should be configured as trust
anchors. Once a Map Resolver authenticates a public key it locally
caches the key along with the associated DDT node RLOC and XEID-
prefix for future use.
10.1. XEID-prefix Delegation
In order to delegate XEID sub-prefixes to its children, a parent DDT
node signs its Map-Referrals. Every signed Map-Referral MUST also
include the public keys associated with each child DDT node. Such a
signature indicates that the parent node is delegating the specified
XEID-prefix to a given child DDT node. The signature is also
authenticating the public keys associated with the children nodes,
and authorizing them to be used by the children DDT nodes to provide
origin authentication and integrity protection for further
Fuller, et al. Expires July 22, 2017 [Page 34]
Internet-Draft LISP Delegated Database Tree January 2017
delegations and mapping information of the XEID-prefix allocated to
the DDT node.
As a result, for a given XEID-prefix, a Map Resolver can form an
authentication chain from a configured trust anchor (typically the
root DDT node) to the leaf nodes (Map Servers). Map Resolvers
leverage this authentication chain to verify the Map-Referral
signatures while walking the DDT tree until they reach a Map Server
authoritative for the given XEID-prefix.
10.2. DDT node operation
Upon receiving a Map-Request, the DDT node responds with a Map-
Referral as specified in Section 7. For every record present in the
Map-Referral, the DDT node also includes the public keys associated
with the record's XEID-prefix and the RLOCs of the children DDT
nodes. Each record contained in the Map-Referral is signed using the
DDT node's private key.
10.2.1. DDT public key revocation
The node that owns a public key can also revoke that public key. For
instance if a parent node advertises a public key for one of its
child DDT nodes, the child DDT node can at a later time revoke that
key. Since DDT nodes do not keep track of the Map Resolvers that
query them, revocation is done in a pull model, where the Map
Resolver is informed of the revocation of a key only when it queries
the node that owns that key. If the parent DDT is configured to
advertise this key, the parent node must also be signaled to remove
the key from the records it advertises for the child DDT node; this
is necessary to avoid further distribution of the revoked key.
To securely revoke a key, the DDT node creates a new Record for the
associated XEID-prefix and locator, including the revoked key with
the R bit set. The DDT node must also include a signature in the
Record that covers this record; this is computed using the private
key corresponding to the key being revoked. Such a record is termed
a "revocation record". By including this record in its Map-
Referrals, the DDT node informs querying Map Resolvers about the
revoked key. A digital signature computed with a revoked key can
only be used to authenticate the revocation, and SHOULD NOT be used
to validate any data. To prevent a compromised key from revoking
other valid keys, a given key can only be used to sign a revocation
for that specific key; it cannot be used to revoke other keys. This
prevents the use of a compromised key to revoke other valid keys as
described in [RFC5011]. A revocation record MUST be advertised for a
period of time equal to or greater than the TTL value of the Record
that initially advertised the key, starting from the time that the
Fuller, et al. Expires July 22, 2017 [Page 35]
Internet-Draft LISP Delegated Database Tree January 2017
advertisement of the key was stopped by removal from the parent DDT
node.
10.3. Map Server operation
Similar to a DDT node, a Map Server is configured with one (or more)
public/private key pairs that it must use to sign Map-Referrals.
However unlike DDT nodes, Map Servers do not delegate prefixes and as
a result they do not need to include keys in the Map-Referrals they
generate.
10.4. Map Resolver operation
Upon receiving a Map-Referral, the Map Resolver MUST first verify the
signature(s) by using a trust anchor, or a previously authenticated
public key, associated with the DDT node sending the Map-Referral.
If multiple authenticated keys are associated with the DDT node
sending this Map-Referral, the Key Tag field of the signature can be
used to select the right public key for verifying the signature. If
the key tag matches more than one key associated with that DDT node,
the Map Resolver MUST try verifying the signature with all matching
keys. For every matching key that is found the Map Resolver MUST
also verify that the key is authoritative for the XEID-prefix in the
Map-Referral record. If such a key is found, the Map Resolver MUST
use it to verify the associated signature in the record. If no
matching key is found, or if none of the matching keys is
authoritative for the XEID-prefix in the Map-Referral record, or if
such a key is found but the signature is not valid the Map-Referral
record is considered corrupted and MUST be discarded. This may be
due to expired keys. The Map Resolver MAY try other siblings of this
node if there is an alternative node authoritative for the same
prefix. If not, the Map Resolver CAN query the DDT node's parent to
retrieve a valid key. It is good practice to use a counter or timer
to avoid repeating this process if the resolver cannot verify the
signature after several trials.
Once the signature is verified, the Map Resolver has verified the
XEID-prefix delegation in the Map-Referral, and authenticated the
public keys of the children DDT nodes. The Map Resolver must add
these keys to the authenticated keys associated with each child DDT
node and XEID-prefix. These keys are considered valid for the
duration specified in the record's TTL field.
Fuller, et al. Expires July 22, 2017 [Page 36]
Internet-Draft LISP Delegated Database Tree January 2017
11. Open Issues and Considerations
There are a number of issues with the organization of the mapping
database that need further investigation. Among these are:
o Defining an interface to implement interconnection and/or
interoperability with other mapping databases, such as LISP+ALT.
o Additional key structures for use with LISP-DDT, such as to
support additional EID formats as defined in [I-D.ietf-lisp-lcaf]
o Management of the DDT Map Resolver referral cache, in particular,
detecting and removing outdated entries.
o Best practices for configuring hint referrals (or vice verse
avoiding using them).
Operational experience will help answer open questions surrounding
these and other issues.
12. IANA Considerations
This document makes no request of the IANA.
13. Security Considerations
Section 10 describes a DDT security architecture that provides data
origin authentication, data integrity protection, and XEID-prefix
delegation within the DDT Infrastructure.
Global XEID-prefix authorization is beyond the scope of this
document, but the SIDR working group [RFC6480] is developing an
infrastructure to support improved security of Internet routing.
Further work is required to determine if SIDR's public key
infrastructure (PKI) and the distributed repository system it uses
for storing and disseminating PKI data objects may also be used by
DDT devices to verifiably assert that they are the legitimate holders
of a set of XEID prefixes.
This document specifies how DDT security and LISP-SEC
([I-D.ietf-lisp-sec]) complement one another to secure the DDT
infrastructure, Map-Referral messages, and the Map-Request/Map-Reply
protocols. In the future other LISP security mechanisms may be
developed to replace LISP-SEC. Such future security mechanisms
should describe how they can be used together with DDT to provide
similar levels of protection.
Fuller, et al. Expires July 22, 2017 [Page 37]
Internet-Draft LISP Delegated Database Tree January 2017
LISP-SEC can use the DDT public key infrastructure to secure the
transport of LISP-SEC key material (the One-Time Key) from a Map-
Resolver to the corresponding Map-Server. For this reason, when
LISP-SEC is deployed in conjunction with a LISP-DDT mapping database
and the path between Map-Resolver and Map-Server needs to be
protected, DDT security as described in Section 10 should be enabled
as well.
14. References
14.1. Normative References
[I-D.ietf-lisp-lcaf]
Farinacci, D., Meyer, D., and J. Snijders, "LISP Canonical
Address Format (LCAF)", draft-ietf-lisp-lcaf-22 (work in
progress), November 2016.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC3447] Jonsson, J. and B. Kaliski, "Public-Key Cryptography
Standards (PKCS) #1: RSA Cryptography Specifications
Version 2.1", RFC 3447, DOI 10.17487/RFC3447, February
2003, <http://www.rfc-editor.org/info/rfc3447>.
[RFC6830] Farinacci, D., Fuller, V., Meyer, D., and D. Lewis, "The
Locator/ID Separation Protocol (LISP)", RFC 6830,
DOI 10.17487/RFC6830, January 2013,
<http://www.rfc-editor.org/info/rfc6830>.
[RFC6833] Fuller, V. and D. Farinacci, "Locator/ID Separation
Protocol (LISP) Map-Server Interface", RFC 6833,
DOI 10.17487/RFC6833, January 2013,
<http://www.rfc-editor.org/info/rfc6833>.
14.2. Informative References
[AFI] "Address Family Identifier (AFIs)", IANA , Febuary 2007,
<http://www.iana.org/assignments/address-family-numbers/
address-family-numbers.xhtml>.
[I-D.ietf-lisp-sec]
Maino, F., Ermagan, V., Cabellos-Aparicio, A., and D.
Saucez, "LISP-Security (LISP-SEC)", draft-ietf-lisp-sec-12
(work in progress), November 2016.
Fuller, et al. Expires July 22, 2017 [Page 38]
Internet-Draft LISP Delegated Database Tree January 2017
[LISP-TREE]
Jakab, L., Cabellos-Aparicio, A., Coras, F., Saucez, D.,
and O. Bonaventure, "LISP-TREE: a DNS hierarchy to support
the lisp mapping system", Selected Areas in
Communications, IEEE Journal , 2010,
<http://ieeexplore.ieee.org/xpls/
abs_all.jsp?arnumber=5586446>.
[RFC1918] Rekhter, Y., Moskowitz, B., Karrenberg, D., de Groot, G.,
and E. Lear, "Address Allocation for Private Internets",
BCP 5, RFC 1918, DOI 10.17487/RFC1918, February 1996,
<http://www.rfc-editor.org/info/rfc1918>.
[RFC5011] StJohns, M., "Automated Updates of DNS Security (DNSSEC)
Trust Anchors", STD 74, RFC 5011, DOI 10.17487/RFC5011,
September 2007, <http://www.rfc-editor.org/info/rfc5011>.
[RFC6480] Lepinski, M. and S. Kent, "An Infrastructure to Support
Secure Internet Routing", RFC 6480, DOI 10.17487/RFC6480,
February 2012, <http://www.rfc-editor.org/info/rfc6480>.
[RFC6836] Fuller, V., Farinacci, D., Meyer, D., and D. Lewis,
"Locator/ID Separation Protocol Alternative Logical
Topology (LISP+ALT)", RFC 6836, DOI 10.17487/RFC6836,
January 2013, <http://www.rfc-editor.org/info/rfc6836>.
[RFC6837] Lear, E., "NERD: A Not-so-novel Endpoint ID (EID) to
Routing Locator (RLOC) Database", RFC 6837,
DOI 10.17487/RFC6837, January 2013,
<http://www.rfc-editor.org/info/rfc6837>.
Appendix A. Acknowledgments
The authors would like to express their thanks to Lorand Jakab,
Albert Cabellos-Asparicio, Florin Coras, Damien Saucez, and Olivier
Bonaventure for their work on LISP-TREE [LISP-TREE] and LISP iterable
mappings that inspired the hierarchical database structure and lookup
iteration approach described in this document. Thanks also go to
Dino Farinacci and Isidor Kouvelas for their implementation work; to
Selina Heimlich and Srin Subramanian for testing; to Fabio Maino for
work on security processing; and to Job Snijders, Glen Wiley, Neel
Goyal, and Mike Gibbs for work on operational considerations and
initial deployment of a prototype database infrastructure. Special
thanks go to Jesper Skriver, Andrew Partan, and Noel Chiappa; all of
whom have participated in (and put up with) seemingly endless hours
of discussion of mapping database ideas, concepts, and issues.
Fuller, et al. Expires July 22, 2017 [Page 39]
Internet-Draft LISP Delegated Database Tree January 2017
Authors' Addresses
Vince Fuller
Email: vaf@vaf.net
Darrel Lewis
Cisco Systems
Email: darlewis@cisco.com
Vina Ermagan
Cisco Systems
Email: vermagan@cisco.com
Amit Jain
Juniper Networks
Email: atjain@juniper.net
Anton Smirnov
Cisco Systems
Email: as@cisco.com
Fuller, et al. Expires July 22, 2017 [Page 40]
