Internet DRAFT - draft-ietf-homenet-hncp
draft-ietf-homenet-hncp
Homenet Working Group M. Stenberg
Internet-Draft S. Barth
Intended status: Standards Track Independent
Expires: May 30, 2016 P. Pfister
Cisco Systems
November 27, 2015
Home Networking Control Protocol
draft-ietf-homenet-hncp-10
Abstract
This document describes the Home Networking Control Protocol (HNCP),
an extensible configuration protocol and a set of requirements for
home network devices. HNCP is described as a profile of and
extension to the Distributed Node Consensus Protocol (DNCP). HNCP
enables discovery of network borders, automated configuration of
addresses, name resolution, service discovery, and the use of any
routing protocol which supports routing based on both source and
destination address.
Status of This Memo
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This Internet-Draft will expire on May 30, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Applicability . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Requirements language . . . . . . . . . . . . . . . . . . 7
3. DNCP Profile . . . . . . . . . . . . . . . . . . . . . . . . 7
4. HNCP Versioning and Router Capabilities . . . . . . . . . . . 8
5. Interface Classification . . . . . . . . . . . . . . . . . . 9
5.1. Interface Categories . . . . . . . . . . . . . . . . . . 9
5.2. DHCP Aided Auto-Detection . . . . . . . . . . . . . . . . 10
5.3. Algorithm for Border Discovery . . . . . . . . . . . . . 10
6. Autonomous Address Configuration . . . . . . . . . . . . . . 11
6.1. Common Link . . . . . . . . . . . . . . . . . . . . . . . 12
6.2. External Connections . . . . . . . . . . . . . . . . . . 12
6.3. Prefix Assignment . . . . . . . . . . . . . . . . . . . . 14
6.3.1. Prefix Assignment Algorithm Parameters . . . . . . . 14
6.3.2. Making New Assignments . . . . . . . . . . . . . . . 15
6.3.3. Applying Assignments . . . . . . . . . . . . . . . . 16
6.3.4. DHCPv6 Prefix Delegation . . . . . . . . . . . . . . 16
6.4. Node Address Assignment . . . . . . . . . . . . . . . . . 17
6.5. Local IPv4 and ULA Prefixes . . . . . . . . . . . . . . . 18
7. Configuration of Hosts and non-HNCP Routers . . . . . . . . . 19
7.1. IPv6 Addressing and Configuration . . . . . . . . . . . . 19
7.2. DHCPv6 for Prefix Delegation . . . . . . . . . . . . . . 20
7.3. DHCPv4 for Addressing and Configuration . . . . . . . . . 20
7.4. Multicast DNS Proxy . . . . . . . . . . . . . . . . . . . 20
8. Naming and Service Discovery . . . . . . . . . . . . . . . . 21
9. Securing Third-Party Protocols . . . . . . . . . . . . . . . 22
10. Type-Length-Value Objects . . . . . . . . . . . . . . . . . . 22
10.1. HNCP Version TLV . . . . . . . . . . . . . . . . . . . . 23
10.2. External Connection TLV . . . . . . . . . . . . . . . . 24
10.2.1. Delegated Prefix TLV . . . . . . . . . . . . . . . . 24
10.2.2. DHCPv6 Data TLV . . . . . . . . . . . . . . . . . . 26
10.2.3. DHCPv4 Data TLV . . . . . . . . . . . . . . . . . . 26
10.3. Assigned Prefix TLV . . . . . . . . . . . . . . . . . . 27
10.4. Node Address TLV . . . . . . . . . . . . . . . . . . . . 28
10.5. DNS Delegated Zone TLV . . . . . . . . . . . . . . . . . 28
10.6. Domain Name TLV . . . . . . . . . . . . . . . . . . . . 29
10.7. Node Name TLV . . . . . . . . . . . . . . . . . . . . . 30
10.8. Managed PSK TLV . . . . . . . . . . . . . . . . . . . . 30
11. General Requirements for HNCP Nodes . . . . . . . . . . . . . 31
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12. Security Considerations . . . . . . . . . . . . . . . . . . . 33
12.1. Interface Classification . . . . . . . . . . . . . . . . 33
12.2. Security of Unicast Traffic . . . . . . . . . . . . . . 34
12.3. Other Protocols in the Home . . . . . . . . . . . . . . 34
13. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 35
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 35
14.1. Normative references . . . . . . . . . . . . . . . . . . 35
14.2. Informative references . . . . . . . . . . . . . . . . . 37
Appendix A. Changelog [RFC Editor: please remove] . . . . . . . 38
Appendix B. Draft source [RFC Editor: please remove] . . . . . . 39
Appendix C. Implementation [RFC Editor: please remove] . . . . . 39
Appendix D. Acknowledgments . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40
1. Introduction
Home Networking Control Protocol (HNCP) is designed to facilitate
sharing of state among home routers to fulfill the needs of the IPv6
homenet architecture [RFC7368], which assumes zero-configuration
operation, multiple subnets, multiple home routers and (potentially)
multiple upstream service providers providing (potentially) multiple
prefixes to the home network. While RFC7368 sets no requirements for
IPv4 support, HNCP aims to support dual-stack mode of operation, and
therefore the functionality is designed with that in mind. The state
is shared as TLVs transported in the DNCP node state among the
routers (and potentially advanced hosts) to enable:
o Autonomic discovery of network borders (Section 5.3) based on
Distributed Node Consensus Protocol (DNCP) topology.
o Automated portioning of prefixes delegated by the service
providers as well as assigned prefixes to both HNCP and non-HNCP
routers (Section 6.3) using [RFC7695]. Prefixes assigned to HNCP
routers are used to:
* Provide addresses to non-HNCP aware nodes (using SLAAC and
DHCP).
* Provide space in which HNCP nodes assign their own addresses
(Section 6.4).
o Internal and external name resolution, as well as multi-link
service discovery (Section 8).
o Other services not defined in this document, that do need to share
state among homenet nodes, and do not cause rapid and constant TLV
changes (see following applicability section).
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HNCP is a DNCP [I-D.ietf-homenet-dncp]-based protocol and includes a
DNCP profile which defines transport and synchronization details for
sharing state across nodes defined in Section 3. The rest of the
document defines behavior of the services noted above, how the
required TLVs are encoded (Section 10), as well as additional
requirements on how HNCP nodes should behave (Section 11).
1.1. Applicability
While HNCP does not deal with routing protocols directly (except
potentially informing them about internal and external interfaces if
classification specified in Section 5.3 is used), in homenet
environments where multiple IPv6 source-prefixes can be present,
routing based on source and destination address is necessary
[RFC7368]. Ideally, the routing protocol is also zero-configuration
(e.g., no need to configure identifiers or metrics) although HNCP can
be used also with a manually configured routing protocol.
As HNCP uses DNCP as the actual state synchronization protocol, the
applicability statement of DNCP applies here as well; HNCP should not
be used for any data that changes rapidly and constantly. If such
data needs to be published in an HNCP network, a more applicable
protocol should be used for those portions and locators to a server
of said protocol can be announced using HNCP instead. An example for
this is naming and service discovery (Section 8) for which HNCP only
transports DNS server addresses, and no actual per-name or per-
service data of hosts.
HNCP TLVs specified within this document, in steady state, stay
constant, with one exception: as Delegated Prefix TLVs
(Section 10.2.1) do contain lifetimes, they force re-publishing of
that data every time the valid or preferred lifetimes of prefixes are
updated (significantly). Therefore, it is desirable for ISPs to
provide large enough valid and preferred lifetimes to avoid
unnecessary HNCP state churn in homes, but even given non-cooperating
ISPs, the state churn is proportional only to the number of
externally received delegated prefixes and not the home network size,
and should therefore be relatively low.
HNCP assumes a certain level of control over host configuration
servers (e.g., DHCP [RFC2131]) on links that are managed by its
routers. Some HNCP functionality (such as border discovery or some
aspects of naming) might be affected by existing DHCP servers not
aware of the HNCP-managed network and thus might need to be
reconfigured to not result in unexpected behavior.
While HNCP routers can provide configuration to and receive
configuration from non-HNCP routers, they are not able to traverse
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such devices based solely on the protocol as defined in this
document, i.e., HNCP routers that are connected only by different
interfaces of a non-HNCP router will not be part of the same HNCP
network.
While HNCP is designed to be used by (home) routers, it can also be
used by advanced hosts that want to do, e.g., their own address
assignment and routing.
HNCP is link layer agnostic; if a link supports IPv6 (link-local)
multicast and unicast, HNCP will work on it. Trickle retransmissions
and keep-alives will handle both packet loss and non-transitive
connectivity, ensuring eventual convergence.
2. Terminology
The following terms are used as they are defined in [RFC7695]:
o Advertised Prefix Priority
o Advertised Prefix
o Assigned Prefix
o Delegated Prefix
o Prefix Adoption
o Private Link
o Published Assigned Prefix
o Applied Assigned Prefix
o Shared Link
The following terms are used as they are defined in
[I-D.ietf-homenet-dncp]:
o DNCP profile
o Node identifier
o Link
o Interface
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(HNCP) node A device implementing this specification.
(HNCP) router A device implementing this specification, which
forwards traffic on behalf of other devices.
highest node When comparing the DNCP node identifiers of
identifier multiple nodes, the one that has the highest value
in a bitwise comparison.
Border separation point between administrative domains; in
this case, between the home network and any other
network, i.e., usually an ISP network.
Internal link a link that does not cross borders.
Internal an interface that is connected to an internal link.
interface
External an interface that is connected to a link which is
interface not an internal link.
Interface a local configuration denoting the use of a
category particular interface. The interface category
determines how a HNCP node should treat the
particular interface. External and internal
category mark the interface as out of or within the
network border; there are also a number of sub-
categories to internal that further affect local
node behavior. See Section 5.1 for a list of
interface categories and how they behave. The
internal or external categories may also be auto-
detected (Section 5.3).
Border router a router announcing external connectivity and
forwarding traffic across the network border.
Common Link a set of nodes on a link which share a common view
of it, i.e., they see each other's traffic and the
same set of hosts. Unless configured otherwise
transitive connectivity is assumed.
DHCPv4 refers to Dynamic Host Configuration Protocol
[RFC2131] in this document.
DHCPv6 refers to Dynamic Host Configuration Protocol for
IPv6 (DHCPv6) [RFC3315] in this document.
DHCP refers to cases which apply to both DHCPv4 and
DHCPv6 in this document.
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2.1. Requirements language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
3. DNCP Profile
The DNCP profile for HNCP is defined as follows:
o HNCP uses UDP datagrams on port HNCP-UDP-PORT as a transport over
link-local scoped IPv6, using unicast and multicast (All-Homenet-
Nodes is the HNCP group address). Received datagrams where either
or both of the IPv6 source or destination address is not link-
local scoped MUST be ignored. Replies to multicast and unicast
messages MUST be sent to the IPv6 source address and port of the
original message. Each node MUST be able to receive (and
potentially reassemble) UDP datagrams with a payload of at least
4000 bytes.
o HNCP operates on multicast-capable interfaces only. HNCP nodes
MUST assign a non-zero 32-bit endpoint identifier to each
interface for which HNCP is enabled. The value zero is not used
in DNCP TLVs, but has a special meaning in HNCP TLVs (see
Section 10.3 and Section 6.4). These identifiers MUST be locally
unique within the scope of the node and using values equivalent to
the IPv6 link-local scope identifiers for the given interfaces are
RECOMMENDED.
o HNCP uses opaque 32-bit node identifiers
(DNCP_NODE_IDENTIFIER_LENGTH = 32). A node implementing HNCP
SHOULD use a random node identifier. If there is a node
identifier collision (as specified in the Node State TLV handling
of Section 4.4 of [I-D.ietf-homenet-dncp]), the node MUST
immediately generate and use a new random node identifier which is
not used by any other node at the time, based on the current DNCP
network state.
o HNCP nodes MUST use the leading 64 bits of the MD5 message digest
[RFC1321] as the DNCP hash function H(x) used in building the DNCP
hash tree.
o HNCP nodes MUST use DNCP's per-endpoint keep-alive extension on
all endpoints. The following parameters are suggested:
* Default keep-alive interval (DNCP_KEEPALIVE_INTERVAL): 20
seconds.
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* Multiplier (DNCP_KEEPALIVE_MULTIPLIER): 2.1 on virtually
lossless links works fine as it allows for one lost keep-alive.
If used on a lossy link, considerably higher multiplier, such
as 15, should be used instead. In that case, an implementation
might prefer shorter keep-alive intervals on that link as well
to ensure that DNCP_KEEPALIVE_INTERVAL *
DNCP_KEEPALIVE_MULTIPLIER timeout after which (entirely) lost
nodes time out is low enough.
o HNCP nodes use the following Trickle parameters for the per-
interface Trickle instances:
* k SHOULD be 1, as the timer reset when data is updated and
further retransmissions should handle packet loss. Even on a
non-transitive lossy link, the eventual per-endpoint keep-
alives should ensure status synchronization occurs.
* Imin SHOULD be 200 milliseconds but MUST NOT be lower. Note:
Earliest transmissions may occur at Imin / 2.
* Imax SHOULD be 7 doublings of Imin [RFC6206] but MUST NOT be
lower.
o HNCP unicast traffic SHOULD be secured using DTLS [RFC6347] as
described in DNCP if exchanged over unsecured links. UDP on port
HNCP-DTLS-PORT is used for this purpose. A node implementing HNCP
security MUST support the DNCP Pre-Shared Key method, SHOULD
support the PKI-based trust method and MAY support the DNCP
Certificate Based Trust Consensus method. [RFC7525] provides
guidance on how to securely utilize DTLS.
o HNCP nodes MUST ignore all Node State TLVs received via multicast
on a link which has DNCP security enabled in order to prevent
spoofing of node state changes.
4. HNCP Versioning and Router Capabilities
Multiple versions of HNCP based on compatible DNCP profiles may be
present in the same network when transitioning between HNCP versions
and for troubleshooting purposes it might be beneficial to identify
the HNCP agent version running. Therefore each node MUST include an
HNCP-Version TLV (Section 10.1) indicating the currently supported
version in its Node Data and MUST ignore (except for DNCP
synchronization purposes) any TLVs with a type greater than 32
published by nodes not also publishing an HNCP-Version TLV.
HNCP routers may also have different capabilities regarding
interactions with hosts, e.g., for configuration or service
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discovery. These are indicated by M, P, H and L values. The
combined "capability value" is a metric indicated by interpreting the
bits as an integer, i.e., (M << 12 | P << 8 | H << 4 | L). These
values are used to elect certain servers on a Common Link, as
described in Section 7. Nodes that are not routers MUST announce the
value 0 for all capabilities. Any node announcing the value 0 for a
capability is considered to not advertise said capability and thus
does not take part in the respective election.
5. Interface Classification
5.1. Interface Categories
HNCP specifies the following categories interfaces can be configured
to be in:
Internal category: This declares an interfaces to be internal, i.e.,
within the borders of the HNCP network. The interface MUST
operate as a DNCP endpoint. Routers MUST forward traffic with
appropriate source addresses between their internal interfaces and
allow internal traffic to reach external networks. All nodes MUST
implement this category and nodes not implementing any other
category implicitly use it as a fixed default.
External category: This declares an interface to be external, i.e.,
not within the borders of the HNCP network. The interface MUST
NOT operate as a DNCP endpoint. Accessing internal resources from
external interfaces is restricted, i.e., the use of Recommended
Simple Security Capabilities in CPEs [RFC6092] is RECOMMENDED.
HNCP routers SHOULD announce acquired configuration information
for use in the network as described in Section 6.2, if the
interface appears to be connected to an external network. HNCP
routers MUST implement this category.
Leaf category: This declares an interface used by client devices
only. Such an interface uses the Internal category with the
exception that it MUST NOT operate as a DNCP endpoint This
category SHOULD be supported by HNCP routers.
Guest category: This declares an interface used by untrusted client
devices only. In addition to the restrictions of the Leaf
category, HNCP routers MUST filter traffic from and to the
interface such that connected devices are unable to reach other
devices inside the HNCP network or query services advertised by
them unless explicitly allowed. This category SHOULD be supported
by HNCP routers.
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Ad-hoc category: This configures an interface to use the Internal
category but no assumption is made about the the link's
transitivity. All other interface categories assume transitive
connectivity. This affects the Common Link (Section 6.1)
definition. Support for this category is OPTIONAL.
Hybrid category: This declares an interface to use the Internal
category while still trying to acquire (external) configuration
information on it, e.g., by running DHCP clients. This is useful,
e.g., if the link is shared with a non-HNCP router under control
and still within the borders of the same network. Detection of
this category automatically in addition to manual configuration is
out of scope of this document. Support for this category is
OPTIONAL.
5.2. DHCP Aided Auto-Detection
Auto-detection of interface categories is possible based on
interaction with DHCPv4 [RFC2131] and DHCPv6-PD [RFC3633] servers on
connected links. HNCP defines special DHCP behavior to differentiate
its internal servers from external ones in order to achieve this.
Therefore all internal devices (including HNCP nodes) running DHCP
servers on links where auto-detection is used by any HNCP node MUST
use the following mechanism based on The User Class Option for DHCPv4
[RFC3004] and its DHCPv6 counterpart [RFC3315]:
o The device MUST ignore or reject DHCP-Requests containing a DHCP
User-Class consisting of the ASCII-String "HOMENET".
Not following this rule (e.g., running unmodified DHCP servers) might
lead to false positives when auto-detection is used, i.e., HNCP nodes
assume an interface to not be internal, even though it was intended
to be.
5.3. Algorithm for Border Discovery
This section defines the interface classification algorithm. It is
suitable for both IPv4 and IPv6 (single or dual-stack) and detects
the category of an interface either automatically or based on a fixed
configuration. By determining the category for all interfaces, the
network borders are implicitly defined, i.e., all interfaces not
belonging to the External category are considered to be within the
borders of the network, all others are not.
The following algorithm MUST be implemented by any node implementing
HNCP. However, if the node does not implement auto-detection, only
the first and last step are required. The algorithm works as
follows, with evaluation stopping at first match:
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1. If a fixed category is configured for an interface, it is used.
2. If a delegated prefix could be acquired by running a DHCPv6
client, it is considered external. The DHCPv6 client MUST have
included a DHCPv6 User-Class consisting of the ASCII-String
"HOMENET" in all of its requests.
3. If an IPv4 address could be acquired by running a DHCPv4 client
on the interface, it is considered external. The DHCPv4 client
MUST have included a DHCP User-Class consisting of the ASCII-
String "HOMENET" in all of its requests.
4. The interface is considered internal.
Note that as other HNCP nodes will ignore the client due to the user
class option, any server that replies is clearly external (or a
malicious internal node).
An HNCP router SHOULD allow setting the fixed category for each
interface which may be connected to either an internal or external
device (e.g., an Ethernet port that can be connected to a modem,
another HNCP router or a client). Note that all fixed categories
except internal and external cannot be auto-detected and can only be
selected using manual configuration.
An HNCP router using auto-detection on an interface MUST run the
appropriately configured DHCP clients as long as the interface
without a fixed category is active (including states where auto-
detection considers it to be internal) and rerun the algorithm above
to react to conditions resulting in a different interface category.
The router SHOULD wait for a reasonable time period (5 seconds as a
default), during which the DHCP clients can acquire a lease, before
treating a newly activated or previously external interface as
internal.
6. Autonomous Address Configuration
This section specifies how HNCP nodes configure host and node
addresses. At first border routers share information obtained from
service providers or local configuration by publishing one or more
External Connection TLVs (Section 10.2). These contain other TLVs
such as Delegated Prefix TLVs (Section 10.2.1) which are then used
for prefix assignment. Finally, HNCP nodes obtain addresses either
statelessly or using a specific stateful mechanism (Section 6.4).
Hosts and non-HNCP routers are configured using SLAAC, DHCP or
DHCPv6-PD.
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6.1. Common Link
HNCP uses the concept of Common Link both in autonomic address
configuration and naming and service discovery (Section 8). A Common
Link refers to the set of interfaces of nodes that see each other's
traffic and presumably also the traffic of all hosts that may use the
nodes to, e.g., forward traffic. Common Links are used, e.g., to
determine where prefixes should be assigned or which peers
participate in the election of a DHCP server. The Common Link is
computed separately for each local internal interface, and it always
contains the local interface. Additionally, if the local interface
is not set to ad-hoc category (see Section 5.1), it also contains the
set of interfaces that are bidirectionally reachable from the given
local interface, that is, every remote interface of a remote node
meeting all of the following requirements:
o The local node publishes a Peer TLV with:
* Peer Node Identifier = remote node's node identifier
* Peer Endpoint Identifier = remote interface's endpoint
identifier
* Endpoint Identifier = local interface's endpoint identifier
o The remote node publishes a Peer TLV with:
* Peer Node Identifier = local node's node identifier
* Peer Endpoint Identifier = local interface's endpoint
identifier
* Endpoint Identifier = remote interface's endpoint identifier
A node MUST be able to detect whether two of its local internal
interfaces are connected, e.g., by detecting an identical remote
interface being part of the Common Links of both local interfaces.
6.2. External Connections
Each HNCP router MAY obtain external connection information such as
address prefixes, DNS server addresses and DNS search paths from one
or more sources, e.g., DHCPv6-PD [RFC3633], NETCONF [RFC6241] or
static configuration. Each individual external connection to be
shared in the network is represented by one External Connection TLV
(Section 10.2).
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Announcements of individual external connections can consist of the
following components:
Delegated Prefixes: address space available for assignment to
internal links announced using Delegated Prefix TLVs
(Section 10.2.1). Some address spaces might have special
properties which are necessary to understand in order to handle
them (e.g., information similar to [RFC6603]). This information
is encoded using DHCPv6 Data TLVs (Section 10.2.2) inside the
respective Delegated Prefix TLVs.
Auxiliary Information: information about services such as DNS or
time synchronization regularly used by hosts in addition to
addressing and routing information. This information is encoded
using DHCPv6 Data TLVs (Section 10.2.2) and DHCPv4 Data TLVs
(Section 10.2.3).
Whenever information about reserved parts (e.g., as specified in
[RFC6603]) is received for a delegated prefix, the reserved parts
MUST be advertised using Assigned Prefix TLVs (Section 10.3) with the
highest priority (i.e., 15), as if they were assigned to a Private
Link.
Some connections or delegated prefixes may have a special meaning and
are not regularly used for internal or internet connectivity, instead
they may provide access to special services like VPNs, sensor
networks, VoIP, IPTV, etc. Care must be taken that these prefixes
are properly integrated and dealt with in the network, in order to
avoid breaking connectivity for devices who are not aware of their
special characteristics or to only selectively allow certain devices
to use them. Such prefixes are distinguished using Prefix Policy
TLVs (Section 10.2.1.1). Their contents MAY be partly opaque to HNCP
nodes, and their identification and usage depends on local policy.
However the following general rules MUST be adhered to:
Special rules apply when making address assignments for prefixes
with Prefix Policy TLVs with type 131, as described in
Section 6.3.2
In presence of any type 1 to 128 Prefix Policy TLV the prefix is
specialized to reach destinations denoted by any such Prefix
Policy TLV, i.e., in absence of a type 0 Prefix Policy TLV it is
not usable for general internet connectivity. An HNCP router MAY
enforce this restriction with appropriate packet filter rules.
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6.3. Prefix Assignment
HNCP uses the Prefix Assignment Algorithm [RFC7695] in order to
assign prefixes to HNCP internal links and uses some of the
terminology (Section 2) defined there. HNCP furthermore defines the
Assigned Prefix TLV (Section 10.3) which MUST be used to announce
Published Assigned Prefixes.
6.3.1. Prefix Assignment Algorithm Parameters
All HNCP nodes running the prefix assignment algorithm use the
following values for its parameters:
Node IDs: HNCP node identifiers are used. The comparison operation
is defined as bit-wise comparison.
Set of Delegated Prefixes: The set of prefixes encoded in Delegated
Prefix TLVs which are not strictly included in prefixes encoded in
other Delegated Prefix TLVs. Note that Delegated Prefix TLVs
included in ignored External Connection TLVs are not considered.
It is dynamically updated as Delegated Prefix TLVs are added or
removed.
Set of Shared Links: The set of Common Links associated with
interfaces with internal, leaf, guest or ad-hoc category. It is
dynamically updated as interfaces are added, removed, or switch
from one category to another. When multiple interfaces are
detected as belonging to the same Common Link, prefix assignment
is disabled on all of these interfaces except one.
Set of Private Links: This document defines Private Links
representing DHCPv6-PD clients or as a mean to advertise prefixes
included in the DHCPv6 Exclude Prefix option. Other
implementation-specific Private Links may be defined whenever a
prefix needs to be assigned for a purpose that does not require a
consensus with other HNCP nodes.
Set of Advertised Prefixes: The set of prefixes included in
Assigned Prefix TLVs advertised by other HNCP nodes (Prefixes
advertised by the local node are not in this set). The associated
Advertised Prefix Priority is the priority specified in the TLV.
The associated Shared Link is determined as follows:
* If the Link Identifier is zero, the Advertised Prefix is not
assigned on a Shared Link.
* If the other node's interface identified by the Link Identifier
is included in one of the Common Links used for prefix
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assignment, it is considered as assigned on the given Common
Link.
* Otherwise, the Advertised Prefix is not assigned on a Shared
Link.
Advertised Prefixes as well as their associated priorities and
associated Shared Links MUST be updated as Assigned Prefix TLVs
are added, updated or removed, and as Common Links are modified.
ADOPT_MAX_DELAY: The default value is 0 seconds (i.e., prefix
adoption is done instantly).
BACKOFF_MAX_DELAY: The default value is 4 seconds.
RANDOM_SET_SIZE: The default value is 64.
Flooding Delay: The default value is 5 seconds.
Default Advertised Prefix Priority: When a new assignment is
created or an assignment is adopted - as specified in the prefix
assignment algorithm routine - the default Advertised Prefix
Priority to be used is 2.
6.3.2. Making New Assignments
Whenever the prefix assignment algorithm subroutine (Section 4.1 of
[RFC7695]) is run on a Common Link and whenever a new prefix may be
assigned (case 1 of the subroutine: no Best Assignment and no Current
Assignment), the decision of whether the assignment of a new prefix
is desired MUST follow these rules in order:
If the Delegated Prefix TLV contains a DHCPv6 Data TLV, and the
meaning of one of the DHCP options is not understood by the HNCP
node, the creation of a new prefix is not desired. This rule
applies to TLVs inside Delegated Prefix TLVs but not to those
inside External Connection TLVs.
If the remaining preferred lifetime of the prefix is 0 and there
is another delegated prefix of the same IP version used for prefix
assignment with a non-zero preferred lifetime, the creation of a
new prefix is not desired.
If the Delegated Prefix does not include a Prefix Policy TLV
indicating restrictive assignment (type 131) or if local policy
exists to identify it based on, e.g., other Prefix Policy TLV
values and allows assignment, the creation of a new prefix is
desired.
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Otherwise, the creation of a new prefix is not desired.
If the considered delegated prefix is an IPv6 prefix, and whenever
there is at least one available prefix of length 64, a prefix of
length 64 MUST be selected unless configured otherwise. In case no
prefix of length 64 would be available, a longer prefix MAY be
selected even without configuration.
If the considered delegated prefix is an IPv4 prefix (Section 6.5
details how IPv4 delegated prefixes are generated), a prefix of
length 24 SHOULD be preferred.
In any case, an HNCP router making an assignment MUST support a
mechanism suitable to distribute addresses from the considered prefix
if the link is intended to be used by clients. In this case a router
assigning an IPv4 prefix MUST announce the L-capability and a router
assigning an IPv6 prefix with a length greater than 64 MUST announce
the H-capability as defined in Section 4.
6.3.3. Applying Assignments
The prefix assignment algorithm indicates when a prefix is applied to
the respective Common Link. When that happens each router connected
to said link:
MUST forward traffic destined to said prefix to the respective
link.
MUST participate in the client configuration election as described
in Section 7, if the link is intended to be used by clients.
MAY add an address from said prefix to the respective network
interface as described in Section 6.4, e.g., if it is to be used
as source for locally originating traffic.
6.3.4. DHCPv6 Prefix Delegation
When an HNCP router announcing the P-Capability (Section 4) receives
a DHCPv6-PD request from a client, it SHOULD assign one prefix per
delegated prefix in the network. This set of assigned prefixes is
then delegated to the client, after it has been applied as described
in the prefix assignment algorithm. Each DHCPv6-PD client MUST be
considered as an independent Private Link and delegation MUST be
based on the same set of Delegated Prefixes as the one used for
Common Link prefix assignments, however the prefix length to be
delegated MAY be smaller than 64.
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The assigned prefixes MUST NOT be given to DHCPv6-PD clients before
they are applied, and MUST be withdrawn whenever they are destroyed.
As an exception to this rule, in order to shorten delays of processed
requests, a router MAY prematurely give out a prefix which is
advertised but not yet applied if it does so with a valid lifetime of
not more than 30 seconds and ensures removal or correction of
lifetimes as soon as possible.
6.4. Node Address Assignment
This section specifies how HNCP nodes reserve addresses for their own
use. Nodes MAY, at any time, try to reserve a new address from any
Applied Assigned Prefix. Each HNCP node SHOULD announce an IPv6
address and - if it supports IPv4 - MUST announce an IPv4 address,
whenever matching prefixes are assigned to at least one of its Common
Links. These addresses are published using Node Address TLVs and
used to locally reach HNCP nodes for other services. Nodes SHOULD
NOT create and announce more than one assignment per IP version to
avoid cluttering the node data with redundant information unless a
special use case requires it.
Stateless assignment based on Semantically Opaque Interface
Identifiers [RFC7217] SHOULD be used for address assignment whenever
possible (e.g., the prefix length is 64), otherwise (e.g., for IPv4
if supported) the following method MUST be used instead: For any
assigned prefix for which stateless assignment is not used, the first
quarter of the addresses are reserved for HNCP based address
assignments, whereas the last three quarters are left to the DHCP
elected router (Section 4 specifies the DHCP server election
process). For example, if the prefix 192.0.2.0/24 is assigned and
applied to a Common Link, addresses included in 192.0.2.0/26 are
reserved for HNCP nodes and the remaining addresses are reserved for
the elected DHCPv4 server.
HNCP nodes assign themselves addresses, and then (to ensure eventual
lack of conflicting assignments) publish the assignments using the
Node Address TLV (Section 10.4).
The process of obtaining addresses is specified as follows:
o A node MUST NOT start advertising an address if it is already
advertised by another node.
o An assigned address MUST be part of an assigned prefix currently
applied on a Common Link which includes the interface specified by
the endpoint identifier.
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o An address MUST NOT be used unless it has been advertised for at
least ADDRESS_APPLY_DELAY consecutive seconds, and is still
currently being advertised. The default value for
ADDRESS_APPLY_DELAY is 3 seconds.
o Whenever the same address is advertised by more than one node, all
but the one advertised by the node with the highest node
identifier MUST be removed.
6.5. Local IPv4 and ULA Prefixes
HNCP routers can create a Unique Local Address (ULA) or private IPv4
prefix to enable connectivity between local devices. These prefixes
are inserted in HNCP as if they were delegated prefixes of a
(virtual) external connection (Section 6.2). The following rules
apply:
An HNCP router SHOULD create a ULA prefix if there is no other
IPv6 prefix with a preferred time greater than 0 in the network.
It MAY also do so, if there are other delegated IPv6 prefixes, but
none of which is locally generated (i.e., without any Prefix
Policy TLV) and has a preferred time greater than 0. However, it
MUST NOT do so otherwise. In case multiple locally generated ULA
prefixes are present, only the one published by the node with the
highest node identifier is kept among those with a preferred time
greater than 0 - if there is any.
An HNCP router MUST create a private IPv4 prefix [RFC1918]
whenever it wishes to provide IPv4 internet connectivity to the
network and no other private IPv4 prefix with internet
connectivity currently exists. It MAY also enable local IPv4
connectivity by creating a private IPv4 prefix if no IPv4 prefix
exists but MUST NOT do so otherwise. In case multiple IPv4
prefixes are announced, only the one published by the node with
the highest node identifier is kept among those with a Prefix
Policy of type 0 - if there is any. The router publishing a
prefix with internet connectivity MUST forward IPv4 traffic to the
internet and perform NAT on behalf of the network as long as it
publishes the prefix, other routers in the network MAY choose not
to.
Creation of such ULA and IPv4 prefixes MUST be delayed by a random
timespan between 0 and 10 seconds in which the router MUST scan for
others trying to do the same.
When a new ULA prefix is created, the prefix is selected based on the
configuration, using the last non-deprecated ULA prefix, or generated
based on [RFC4193].
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7. Configuration of Hosts and non-HNCP Routers
HNCP routers need to ensure that hosts and non-HNCP downstream
routers on internal links are configured with addresses and routes.
Since DHCP clients can usually only bind to one server at a time, a
per-link and per-service election takes place.
HNCP routers may have different capabilities for configuring
downstream devices and providing naming services. Each router MUST
therefore indicate its capabilities as specified in Section 4 in
order to participate as a candidate in the election.
7.1. IPv6 Addressing and Configuration
In general Stateless Address Autoconfiguration [RFC4861] is used for
client configuration for its low overhead and fast renumbering
capabilities. Therefore each HNCP router sends Router Advertisements
on interfaces which are intended to be used by clients and MUST at
least include a Prefix Information Option for each Applied Assigned
Prefix which it assigned to the respective link in every such
advertisement. However, stateful DHCPv6 can be used in addition by
administrative choice, to, e.g., collect hostnames and use them to
provide naming services or whenever stateless configuration is not
applicable.
The designated stateful DHCPv6 server for a Common Link (Section 6.1)
is elected based on the capabilities described in Section 4. The
winner is the router (connected to the Common Link) advertising the
greatest H-capability. In case of a tie, Capability Values
(Section 4) are compared, and the router with the greatest value is
elected. In case of another tie, the router with the highest node
identifier is elected among the routers with tied Capability Values.
The elected router MUST serve stateful DHCPv6 and SHOULD provide
naming services for acquired hostnames as outlined in Section 8, all
others nodes MUST NOT. Stateful addresses SHOULD be assigned in a
way not hindering fast renumbering even if the DHCPv6 server or
client do not support the DHCPv6 reconfigure mechanism, e.g., by only
handing out leases from locally-generated (ULA) prefixes and prefixes
with a length different from 64, and by using low renew and rebind
times (i.e., not longer than 5 minutes). In case no router was
elected, stateful DHCPv6 is not provided. Routers which cease to be
elected DHCP servers SHOULD - when applicable - invalidate remaining
existing bindings in order to trigger client reconfiguration.
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7.2. DHCPv6 for Prefix Delegation
The designated DHCPv6 server for prefix-delegation on a Common Link
is elected based on the capabilities described in Section 4. The
winner is the router (connected to the Common Link) advertising the
greatest P-capability. In case of a tie, Capability Values
(Section 4) are compared, and the router with the greatest value is
elected. In case of another tie, the router with the highest node
identifier is elected among the routers with tied Capability Values.
The elected router MUST provide prefix-delegation services [RFC3633]
on the given link (and follow the rules in Section 6.3.4), all other
nodes MUST NOT.
7.3. DHCPv4 for Addressing and Configuration
The designated DHCPv4 server on a Common Link (Section 6.1) is
elected based on the capabilities described in Section 4. The winner
is the router (connected to the Common Link) advertising the greatest
L-capability. In case of a tie, Capability Values (Section 4) are
compared, and the router with the greatest value is elected. In case
of another tie, the router with the highest node identifier is
elected among the routers with tied Capability Values.
The elected router MUST provide DHCPv4 services on the given link,
all other nodes MUST NOT. The elected router MUST provide IP
addresses from the pool defined in Section 6.4 and MUST announce
itself as router [RFC2132] to clients.
DHCPv4 lifetimes renew and rebind times (T1 and T2) SHOULD be short
(i.e., not longer than 5 minutes) in order to provide reasonable
response times to changes. Routers which cease to be elected DHCP
servers SHOULD - when applicable - invalidate remaining existing
bindings in order to trigger client reconfiguration.
7.4. Multicast DNS Proxy
The designated MDNS [RFC6762] proxy on a Common Link is elected based
on the capabilities described in Section 4. The winner is the router
(connected to the Common Link) advertising the greatest M-capability.
In case of a tie, Capability Values (Section 4) are compared, and the
router with the greatest value is elected. In case of another tie,
the router with the highest node identifier is elected among the
routers with tied Capability Values.
The elected router MUST provide an MDNS-proxy on the given link and
announce it as described in Section 8.
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8. Naming and Service Discovery
Network-wide naming and service discovery can greatly improve the
user-friendliness of a network. The following mechanism provides
means to setup and delegate naming and service discovery across
multiple HNCP routers.
Each HNCP router SHOULD provide and advertise a recursive name
resolving server to clients which honors the announcements made in
Delegated Zone TLVs (Section 10.5), Domain Name TLVs (Section 10.6)
and Node Name TLVs (Section 10.7), i.e., delegate queries to the
designated name servers and hand out appropriate A, AAAA and PTR
records according to the mentioned TLVs.
Each HNCP router SHOULD provide and announce an auto-generated or
user-configured name for each internal Common Link (Section 6.1) for
which it is the designated DHCPv4, stateful DHCPv6 server, MDNS
proxy, or for which it provides forward or reverse DNS services on
behalf of connected devices. This announcement is done using
Delegated Zone TLVs (Section 10.5) and MUST be unique in the whole
network. In case of a conflict the announcement of the node with the
highest node identifier takes precedence and all other nodes MUST
cease to announce the conflicting TLV. HNCP routers providing
recursive name resolving services MUST use the included DNS server
address within the TLV to resolve names belonging to the zone as if
there was an NS record.
Each HNCP node SHOULD announce a node name for itself to be easily
reachable and MAY announce names on behalf of other devices.
Announcements are made using Node Name TLVs (Section 10.7) and the
announced names MUST be unique in the whole network. In case of a
conflict the announcement of the node with the highest node
identifier takes precedence and all other nodes MUST cease to
announce the conflicting TLV. HNCP routers providing recursive name
resolving services as described above MUST resolve such announced
names to their respective IP addresses as if there were corresponding
A/AAAA records.
Names and unqualified zones are used in an HNCP network to provide
naming and service discovery with local significance. A network-wide
zone is appended to all single labels or unqualified zones in order
to qualify them. ".home" is the default, however an administrator MAY
configure announcing of a Domain Name TLV (Section 10.6) for the
network to use a different one. In case multiple are announced, the
domain of the node with the greatest node identifier takes
precedence.
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9. Securing Third-Party Protocols
Pre-shared keys (PSKs) are often required to secure (for example)
IGPs and other protocols which lack support for asymmetric security.
The following mechanism manages PSKs using HNCP to enable
bootstrapping of such third-party protocols. The scheme SHOULD NOT
be used unless in conjunction with secured HNCP unicast transport
(i.e., DTLS), as transferring the PSK in plain-text anywhere in the
network is a potential risk, especially as the originator may not
know about security (and use of DNCP security) on all links. The
following rules define how such a PSK is managed and used:
o If no Managed PSK TLV (Section 10.8) is currently being announced,
an HNCP node using this mechanism MUST create one after a random
delay of 0 to 10 seconds with a 32 bytes long random key and add
it to its node data.
o In case multiple nodes announce such a TLV at the same time, all
but the one with the greatest node identifier stop advertising it
and adopt the remaining one.
o The node currently advertising the Managed PSK TLV MUST generate
and advertise a new random one whenever an unreachable node is
removed from the DNCP topology as described in the Section 4.6 of
[I-D.ietf-homenet-dncp].
PSKs for individual protocols SHOULD be derived from the random PSK
using a suitable one-way hashing algorithm (e.g., by using HMAC-
SHA256 based HKDF [RFC6234] with the particular protocol name in the
info field) so that disclosure of any derived key does not impact
other users of the managed PSK. Furthermore derived PSKs MUST be
updated whenever the managed PSK changes.
10. Type-Length-Value Objects
HNCP defines the following TLVs in addition to those defined by DNCP.
The same general rules and defaults for encoding as noted in
Section 7 of [I-D.ietf-homenet-dncp] apply. Note that most HNCP
variable-length TLVs also support optional nested TLVs, and they are
encoded after the variable length content, followed by the zero
padding of the variable length content to the next 32-bit boundary.
TLVs defined here are only valid when appearing in their designated
context, i.e., only directly within container TLVs mentioned in their
definition, or - absent any mentions - only as top-level TLVs within
the node data set. TLVs appearing outside their designated context
MUST be ignored.
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TLVs encoding IP addresses or prefixes allow encoding both IPv6 and
IPv4 addresses and prefixes. IPv6 information is encoded as is,
whereas for IPv4 IPv4-mapped IPv6 addresses format [RFC4291] is used
and prefix lengths are encoded as original IPv4 prefix length
increased by 96.
10.1. HNCP Version TLV
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: HNCP-VERSION (32) | Length: >= 5 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reserved | M | P | H | L |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| User-agent |
This TLV is used to indicate the supported version and router
capabilities of an HNCP node as described in Section 4.
Reserved: Bits are reserved for future use. They MUST be set to
zero when creating this TLV, and their value MUST be ignored when
processing the TLV.
M-capability: Priority value used for electing the on-link MDNS
[RFC6762] proxy. It MUST be set to 0 if the router is not capable
of proxying MDNS, otherwise it SHOULD be set to 4 but MAY be set
to any value from 1 to 7 to indicate a non-default priority. The
values 8-15 are reserved for future use.
P-capability: Priority value used for electing the on-link DHCPv6-PD
server. It MUST be set to 0 if the router is not capable of
providing prefixes through DHCPv6-PD (Section 6.3.4), otherwise it
SHOULD be set to 4 but MAY be set to any value from 1 to 7 to
indicate a non-default priority. The values 8-15 are reserved for
future use.
H-capability: Priority value used for electing the on-link DHCPv6
server offering non-temporary addresses. It MUST be set to 0 if
the router is not capable of providing such addresses, otherwise
it SHOULD be set to 4 but MAY be set to any value from 1 to 7 to
indicate a non-default priority. The values 8-15 are reserved for
future use.
L-capability: Priority value used for electing the on-link DHCPv4
server. It MUST be set to 0 if the router is not capable of
running a legacy DHCPv4 server offering IPv4 addresses to clients,
otherwise it SHOULD be set to 4 but MAY be set to any value from 1
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to 7 to indicate a non-default priority. The values 8-15 are
reserved for future use.
User-Agent: The user-agent is a human-readable UTF-8 string that
describes the name and version of the current HNCP implementation.
10.2. External Connection TLV
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: EXTERNAL-CONNECTION (33)| Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
An External Connection TLV is a container TLV used to gather network
configuration information associated with a single external
connection (Section 6.2) to be shared across the HNCP network. A
node MAY publish an arbitrary number of instances of this TLV to
share the desired number of external connections. Upon reception,
the information transmitted in any nested TLVs is used for the
purposes of prefix assignment (Section 6.3) and host configuration
(Section 7).
10.2.1. Delegated Prefix TLV
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: DELEGATED-PREFIX (34) | Length: >= 9 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Valid Lifetime Since Origination |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Preferred Lifetime Since Origination |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Length | |
+-+-+-+-+-+-+-+-+ Prefix +
...
| | 0-pad if any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
The Delegated Prefix TLV is used by HNCP routers to advertise
prefixes which are allocated to the whole network and can be used for
prefix assignment. Delegated Prefix TLVs are only valid inside
External Connection TLVs and their prefixes MUST NOT overlap with
those of other such TLVs in the same container.
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Valid Lifetime Since Origination: The time in seconds the delegated
prefix was valid for at the origination time of the node data
containing this TLV. The value MUST be updated whenever the node
republishes its Node State TLV.
Preferred Lifetime Since Origination: The time in seconds the
delegated prefix was preferred for at the origination time of the
node data containing this TLV. The value MUST be updated whenever
the node republishes its Node State TLV.
Prefix Length: The number of significant bits in the Prefix.
Prefix: Significant bits of the prefix padded with zeroes up to the
next byte boundary.
10.2.1.1. Prefix Policy TLV
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: PREFIX-POLICY (43) | Length: >= 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Policy Type | |
+-+-+-+-+-+-+-+-+ Value +
| |
The Prefix Policy TLV contains information about the policy or
applicability of a delegated prefix. This information can be used to
determine whether prefixes for a certain usecase (e.g., local
reachability, internet connectivity) do exist or are to be acquired
and to make decisions about assigning prefixes to certain links or to
fine-tune border firewalls. See Section 6.2 for a more in-depth
discussion. This TLV is only valid inside a Delegated Prefix TLV.
Policy Type: The type of the policy identifier.
0 : Internet connectivity (no Value).
1-128 : Explicit destination prefix with the Policy Type being
the actual length of the prefix and the Value containing
significant bits of the destination prefix padded with zeroes
up to the next byte boundary.
129 : DNS Domain. The Value contains an RFC 1035 [RFC1035]
encoded DNS label sequence. Compression MUST NOT be used. The
label sequence MUST end with an empty label.
130 : Opaque UTF-8 string (e.g., for administrative purposes).
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131 : Restrictive Assignment (no Value).
132-255: Reserved for future additions.
Value: A variable length identifier of the given type.
10.2.2. DHCPv6 Data TLV
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: DHCPV6-DATA (37) | Length: > 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DHCPv6 option stream |
This TLV is used to encode auxiliary IPv6 configuration information
(e.g., recursive DNS servers) encoded as a stream of DHCPv6 options.
It is only valid in an External Connection TLV or a Delegated Prefix
TLV encoding an IPv6 prefix and MUST NOT occur more than once in any
single container. When included in an External Connection TLV, it
contains DHCPv6 options relevant to the External Connection as a
whole. When included in a Delegated Prefix, it contains options
mandatory to handle said prefix.
DHCPv6 option stream: DHCPv6 options encoded as specified in
[RFC3315].
10.2.3. DHCPv4 Data TLV
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: DHCPV4-DATA (38) | Length: > 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| DHCPv4 option stream |
This TLV is used to encode auxiliary IPv4 configuration information
(e.g., recursive DNS servers) encoded as a stream of DHCPv4 options.
It is only valid in an External Connection TLV and MUST NOT occur
more than once in any single container. It contains DHCPv4 options
relevant to the External Connection as a whole.
DHCPv4 option stream: DHCPv4 options encoded as specified in
[RFC2131].
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10.3. Assigned Prefix TLV
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: ASSIGNED-PREFIX (35) | Length: >= 6 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rsv. | Prty. | Prefix Length | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Prefix +
...
| | 0-pad if any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
This TLV is used to announce Published Assigned Prefixes for the
purposes of prefix assignment (Section 6.3).
Endpoint Identifier: The endpoint identifier of the local interface
the prefix is assigned to, or 0 if it is assigned to a Private
Link (e.g., when the prefix is assigned for downstream prefix
delegation).
Rsv.: Bits are reserved for future use. They MUST be set to zero
when creating this TLV, and their value MUST be ignored when
processing the TLV.
Prty: The Advertised Prefix Priority from 0 to 15.
0-1 : Low priorities.
2 : Default priority.
3-7 : High priorities.
8-11 : Administrative priorities. MUST NOT be used unless
configured otherwise.
12-14: Reserved for future use.
15 : Provider priorities. MAY only be used by the router
advertising the corresponding delegated prefix and based on
static or dynamic configuration (e.g., for excluding a prefix
based on DHCPv6-PD Prefix Exclude Option [RFC6603]).
Prefix Length: The number of significant bits in the Prefix field.
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Prefix: The significant bits of the prefix padded with zeroes up to
the next byte boundary.
10.4. Node Address TLV
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: NODE-ADDRESS (36) | Length: 20 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Endpoint Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IP Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
This TLV is used to announce addresses assigned to an HNCP node as
described in Section 6.4.
Endpoint Identifier: The endpoint identifier of the local interface
the prefix is assigned to, or 0 if it is not assigned on an HNCP
enabled link.
IP Address: The globally scoped IPv6 address, or the IPv4 address
encoded as an IPv4-mapped IPv6 address [RFC4291].
10.5. DNS Delegated Zone TLV
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: DNS-DELEGATED-ZONE (39) | Length: >= 17 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IP Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Reserved |L|B|S| |
+-+-+-+-+-+-+-+-+ Zone (DNS label sequence - variable length) |
...
| | 0-pad if any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
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This TLV is used to announce a forward or reverse DNS zone delegation
in the HNCP network. Its meaning is roughly equivalent to specifying
an NS and A/AAAA record for said zone. Details are specified in
Section 8.
IP Address : The IPv6 address of the authoritative DNS server for
the zone; IPv4 addresses are represented as IPv4-mapped addresses
[RFC4291]. The special value of :: (all-zero) means the
delegation is available in the global DNS-hierarchy.
Reserved : Those bits MUST be set to zero when creating the TLV and
ignored when parsing it unless defined in a later specification.
L-bit : DNS-SD [RFC6763] Legacy-Browse, indicates that this
delegated zone SHOULD be included in the network's DNS-SD legacy
browse list of domains at lb._dns- sd._udp.(DOMAIN-NAME). Local
forward zones SHOULD have this bit set, reverse zones SHOULD NOT.
B-bit : (DNS-SD [RFC6763] Browse) indicates that this delegated zone
SHOULD be included in the network's DNS-SD browse list of domains
at b._dns-sd._udp. (DOMAIN-NAME). Local forward zones SHOULD
have this bit set, reverse zones SHOULD NOT.
S-bit : (fully-qualified DNS-SD [RFC6763] domain) indicates that
this delegated zone consists of a fully-qualified DNS-SD domain,
which should be used as base for DNS-SD domain enumeration, i.e.,
_dns-sd._udp.(Zone) exists. Forward zones MAY have this bit set,
reverse zones MUST NOT. This can be used to provision DNS search
path to hosts for non-local services (such as those provided by an
ISP, or other manually configured service providers). Zones with
this flag SHOULD be added to the search domains advertised to
clients.
Zone : The label sequence encoded according to [RFC1035].
Compression MUST NOT be used. The label sequence MUST end with an
empty label.
10.6. Domain Name TLV
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: DOMAIN-NAME (40) | Length: > 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain (DNS label sequence - variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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This TLV is used to indicate the base domain name for the network as
specified in Section 8. This TLV MUST NOT be announced unless the
domain name was explicitly configured by an administrator.
Domain: The label sequence encoded according to [RFC1035].
Compression MUST NOT be used. The label sequence MUST end with an
empty label.
10.7. Node Name TLV
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: NODE-NAME (41) | Length: > 17 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IP Address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Length | Name |
...
| (not null-terminated, variable length) | 0-pad if any |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
This TLV is used to assign the name of a node in the network to a
certain IP address as specified in Section 8.
IP Address: The IP address associated with the name. IPv4
addresses are encoded using IPv4-mapped IPv6 addresses.
Length: The length of the name (0-63).
Name: The name of the node as a single DNS label.
10.8. Managed PSK TLV
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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: MANAGED-PSK (42) | Length: 32 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| |
| Random 256-bit PSK |
| |
| |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (Optional nested TLVs) |
This TLV is used to announce a PSK for securing third-party protocols
exclusively supporting symmetric cryptography as specified in
Section 9.
11. General Requirements for HNCP Nodes
Each node implementing HNCP is subject to the following requirements:
o It MUST implement HNCP-Versioning (Section 4) and Interface
Classification (Section 5).
o It MUST implement and run the method for securing third-party
protocols (Section 9) whenever it uses the security mechanism of
HNCP.
If the node is acting as a router, then the following requirements
apply in addition:
o It MUST support Autonomous Address Configuration (Section 6) and
Configuration of Hosts and non-HNCP Routers (Section 7).
o It SHOULD implement support for the Service Discovery and Naming
(Section 8) as defined in this document.
o It MAY be able to provide connectivity to IPv4-devices using
DHCPv4.
o It SHOULD be able to delegate prefixes to legacy IPv6 routers
using DHCPv6-PD (Section 6.3.4).
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o In addition, normative language of Basic Requirements for IPv6
Customer Edge Routers [RFC7084] applies with the following
adjustments:
* The generic requirements G-4 and G-5 are relaxed such that any
known default router on any interface is sufficient for a
router to announce itself as default router, similarly only the
loss of all such default routers results in self-invalidation.
* The section "WAN-Side Configuration" applies to interfaces
classified as external.
* If the CE sends a size-hint as indicated in WPD-2, the hint
MUST NOT be determined by the number of LAN-interfaces of the
CE, but SHOULD instead be large enough to at least accommodate
prefix assignments announced for existing delegated or ULA-
prefixes, if such prefixes exist and unless explicitly
configured otherwise.
* The dropping of packets with a destination address belonging to
a delegated prefix mandated in WPD-5 MUST NOT be applied to
destinations that are part of any prefix announced using an
Assigned Prefix TLV by any HNCP router in the network.
* The section "LAN-Side Configuration" applies to interfaces not
classified as external.
* The requirement L-2 to assign a separate /64 to each LAN
interface is replaced by the participation in the prefix
assignment mechanism (Section 6.3) for each such interface.
* The requirement L-9 is modified, in that the M flag MUST be set
if and only if a router connected to the respective Common Link
is advertising a non-zero H-capability. The O flag SHOULD
always be set.
* The requirement L-12 to make DHCPv6 options available is
adapted, in that a CER SHOULD publish the subset of options
using the DHCPv6 Data TLV in an External Connection TLV.
Similarly it SHOULD do the same for DHCPv4 options in a DHCPv4
Data TLV. DHCPv6 options received inside an OPTION_IAPREFIX
[RFC3633] MUST be published using a DHCPv6 Data TLV inside the
respective Delegated Prefix TLV. HNCP routers SHOULD make
relevant DHCPv6 and DHCPv4 options available to clients, i.e.,
options contained in External Connection TLVs that also include
delegated prefixes from which a subset is assigned to the
respective link.
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* The requirement L-13 to deprecate prefixes is applied to all
delegated prefixes in the network from which assignments have
been made on the respective interface. Furthermore the Prefix
Information Options indicating deprecation MUST be included in
Router Advertisements for the remainder of the prefixes'
respective valid lifetime, but MAY be omitted after at least 2
hours have passed.
12. Security Considerations
HNCP enables self-configuring networks, requiring as little user
intervention as possible. However this zero-configuration goal
usually conflicts with security goals and introduces a number of
threats.
General security issues for existing home networks are discussed in
[RFC7368]. The protocols used to set up addresses and routes in such
networks to this day rarely have security enabled within the
configuration protocol itself. However these issues are out of scope
for the security of HNCP itself.
HNCP is a DNCP-based state synchronization mechanism carrying
information with varying threat potential. For this consideration
the payloads defined in DNCP and this document are reviewed:
o Network topology information such as HNCP nodes and their common
links.
o Address assignment information such as delegated and assigned
prefixes for individual links.
o Naming and service discovery information such as auto-generated or
customized names for individual links and nodes.
12.1. Interface Classification
As described in Section 5.3, an HNCP node determines the internal or
external state on a per-interface basis. A firewall perimeter is set
up for the external interfaces, and for internal interfaces, HNCP
traffic is allowed, with the exception of leaf and guest sub-
categories.
Threats concerning automatic interface classification cannot be
mitigated by encrypting or authenticating HNCP traffic itself since
external routers do not participate in the protocol and often cannot
be authenticated by other means. These threats include propagation
of forged uplinks in the homenet in order to, e.g., redirect traffic
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destined to external locations and forged internal status by external
routers to, e.g., circumvent the perimeter firewall.
It is therefore imperative to either secure individual links on the
physical or link-layer or preconfigure the adjacent interfaces of
HNCP routers to an appropriate fixed category in order to secure the
homenet border. Depending on the security of the external link
eavesdropping, man-in-the-middle and similar attacks on external
traffic can still happen between a homenet border router and the ISP,
however these cannot be mitigated from inside the homenet. For
example, DHCPv4 has defined [RFC3118] to authenticate DHCPv4
messages, but this is very rarely implemented in large or small
networks. Further, while PPP can provide secure authentication of
both sides of a point to point link, it is most often deployed with
one-way authentication of the subscriber to the ISP, not the ISP to
the subscriber.
12.2. Security of Unicast Traffic
Once the homenet border has been established there are several ways
to secure HNCP against internal threats like manipulation or
eavesdropping by compromised devices on a link which is enabled for
HNCP traffic. If left unsecured, attackers may perform arbitrary
traffic redirection, eavesdropping, spoofing or denial of service
attacks on HNCP services such as address assignment or service
discovery, and the protocols secured using HNCP-derived keys such as
routing protocols.
Detailed interface categories like "leaf" or "guest" can be used to
integrate not fully trusted devices to various degrees into the
homenet by not exposing them to HNCP traffic or by using firewall
rules to prevent them from reaching homenet-internal resources.
On links where this is not practical and lower layers do not provide
adequate protection from attackers, DTLS-based secure unicast
transport MUST be used to secure traffic.
12.3. Other Protocols in the Home
IGPs and other protocols are usually run alongside HNCP therefore the
individual security aspects of the respective protocols must be
considered. It can however be summarized that many protocols to be
run in the home (like IGPs) provide - to a certain extent - similar
security mechanisms. Most of these protocols do not support
encryption and only support authentication based on pre-shared keys
natively. This influences the effectiveness of any encryption-based
security mechanism deployed by HNCP as homenet routing information is
thus usually not encrypted.
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13. IANA Considerations
IANA should set up a registry for the (decimal values within range
32-511) "HNCP TLV Types" under "Distributed Node Consensus Protocol
(DNCP)", with the following initial contents:
32: HNCP-Version
33: External-Connection
34: Delegated-Prefix
35: Assigned-Prefix
36: Node-Address
37: DHCPv4-Data
38: DHCPv6-Data
39: DNS-Delegated-Zone
40: Domain-Name
41: Node-Name
42: Managed-PSK
43: Prefix-Policy
44-511: Free - policy of 'RFC required' [RFC5226] should be used.
The range reserved by DNCP for Private Use (768-1023) is used by
HNCP for per-implementation experimentation. How collisions are
avoided is out of the scope of this document.
HNCP requires allocation of well-known UDP port numbers HNCP-UDP-PORT
(service name: hncp-udp-port, description: HNCP) and HNCP-DTLS-PORT
(service name: hncp-dtls-port, description: HNCP over DTLS), as well
as an IPv6 link-local multicast address All-Homenet-Nodes.
14. References
14.1. Normative references
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[I-D.ietf-homenet-dncp]
Stenberg, M. and S. Barth, "Distributed Node Consensus
Protocol", draft-ietf-homenet-dncp-12 (work in progress),
November 2015.
[RFC7695] Pfister, P., Paterson, B., and J. Arkko, "Distributed
Prefix Assignment Algorithm", RFC 7695, DOI 10.17487/
RFC7695, November 2015,
<http://www.rfc-editor.org/info/rfc7695>.
[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>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
<http://www.rfc-editor.org/info/rfc5226>.
[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <http://www.rfc-editor.org/info/rfc6347>.
[RFC6603] Korhonen, J., Ed., Savolainen, T., Krishnan, S., and O.
Troan, "Prefix Exclude Option for DHCPv6-based Prefix
Delegation", RFC 6603, DOI 10.17487/RFC6603, May 2012,
<http://www.rfc-editor.org/info/rfc6603>.
[RFC6206] Levis, P., Clausen, T., Hui, J., Gnawali, O., and J. Ko,
"The Trickle Algorithm", RFC 6206, DOI 10.17487/RFC6206,
March 2011, <http://www.rfc-editor.org/info/rfc6206>.
[RFC3004] Stump, G., Droms, R., Gu, Y., Vyaghrapuri, R., Demirtjis,
A., Beser, B., and J. Privat, "The User Class Option for
DHCP", RFC 3004, DOI 10.17487/RFC3004, November 2000,
<http://www.rfc-editor.org/info/rfc3004>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC
2131, DOI 10.17487/RFC2131, March 1997,
<http://www.rfc-editor.org/info/rfc2131>.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins,
C., and M. Carney, "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July
2003, <http://www.rfc-editor.org/info/rfc3315>.
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[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
DOI 10.17487/RFC3633, December 2003,
<http://www.rfc-editor.org/info/rfc3633>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
[RFC1321] Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
DOI 10.17487/RFC1321, April 1992,
<http://www.rfc-editor.org/info/rfc1321>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<http://www.rfc-editor.org/info/rfc6763>.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,
<http://www.rfc-editor.org/info/rfc2132>.
[RFC4193] Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, DOI 10.17487/RFC4193, October 2005,
<http://www.rfc-editor.org/info/rfc4193>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217, DOI 10.17487/
RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
[RFC6092] Woodyatt, J., Ed., "Recommended Simple Security
Capabilities in Customer Premises Equipment (CPE) for
Providing Residential IPv6 Internet Service", RFC 6092,
DOI 10.17487/RFC6092, January 2011,
<http://www.rfc-editor.org/info/rfc6092>.
14.2. Informative references
[RFC3118] Droms, R. and W. Arbaugh., Ed., "Authentication for DHCP
Messages", RFC 3118, DOI 10.17487/RFC3118, June 2001,
<http://www.rfc-editor.org/info/rfc3118>.
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[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>.
[RFC7368] Chown, T., Ed., Arkko, J., Brandt, A., Troan, O., and J.
Weil, "IPv6 Home Networking Architecture Principles", RFC
7368, DOI 10.17487/RFC7368, October 2014,
<http://www.rfc-editor.org/info/rfc7368>.
[RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>.
[RFC6234] Eastlake 3rd, D. and T. Hansen, "US Secure Hash Algorithms
(SHA and SHA-based HMAC and HKDF)", RFC 6234, DOI
10.17487/RFC6234, May 2011,
<http://www.rfc-editor.org/info/rfc6234>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013,
<http://www.rfc-editor.org/info/rfc6762>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC7084] Singh, H., Beebee, W., Donley, C., and B. Stark, "Basic
Requirements for IPv6 Customer Edge Routers", RFC 7084,
DOI 10.17487/RFC7084, November 2013,
<http://www.rfc-editor.org/info/rfc7084>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <http://www.rfc-editor.org/info/rfc7525>.
Appendix A. Changelog [RFC Editor: please remove]
draft-ietf-homenet-hncp-10: Mainly IESG review based changes, no real
content change.
draft-ietf-homenet-hncp-09: Added nested TLV definitions for variable
length TLVs. NOTE: Node name TLV encoding includes now length byte.
Version TLV now itself indicates version.
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draft-ietf-homenet-hncp-08: Editorial reorganization.
draft-ietf-homenet-hncp-07: Using version 1 instead of version 0, as
existing implementations already use it.
draft-ietf-homenet-hncp-06: Various edits based on feedback,
hopefully without functional delta.
draft-ietf-homenet-hncp-05: Renamed "Adjacent Link" to "Common Link".
Changed single IPv4 uplink election from MUST to MAY. Added explicit
indication to distinguish (IPv4)-PDs for local connectivity and ones
with uplink connectivity allowing, e.g., better local-only
IPv4-connectivity.
draft-ietf-homenet-hncp-04: Change the responsibility for sending RAs
to the router assigning the prefix.
draft-ietf-homenet-hncp-03: Split to DNCP (generic protocol) and HNCP
(homenet profile).
draft-ietf-homenet-hncp-02: Removed any built-in security. Relying
on IPsec. Reorganized interface categories, added requirements
languages, made manual border configuration a MUST-support.
Redesigned routing protocol election to consider non-router devices.
draft-ietf-homenet-hncp-01: Added (MAY) guest, ad-hoc, hybrid
categories for interfaces. Removed old hnetv2 reference, and now
pointing just to OpenWrt + github. Fixed synchronization algorithm
to spread also same update number, but different data hash case.
Made purge step require bidirectional connectivity between nodes when
traversing the graph. Edited few other things to be hopefully
slightly clearer without changing their meaning.
draft-ietf-homenet-hncp-00: Added version TLV to allow for TLV
content changes pre-RFC without changing IDs. Added link id to
assigned address TLV.
Appendix B. Draft source [RFC Editor: please remove]
This draft is available at https://github.com/fingon/ietf-drafts/ in
source format. Issues and pull requests are welcome.
Appendix C. Implementation [RFC Editor: please remove]
A GPLv2-licensed implementation of HNCP is currently under
development at https://github.com/sbyx/hnetd/ and binaries are
available in the OpenWrt package repositories (
http://www.openwrt.org ). See http://www.homewrt.org/
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doku.php?id=run-conf for more information. Feedback and
contributions are welcome.
Appendix D. Acknowledgments
Thanks to Ole Troan, Mark Baugher, Mark Townsley, Juliusz Chroboczek
and Thomas Clausen for their contributions to the draft.
Thanks to Eric Kline for the original border discovery work.
Authors' Addresses
Markus Stenberg
Independent
Helsinki 00930
Finland
Email: markus.stenberg@iki.fi
Steven Barth
Independent
Halle 06114
Germany
Email: cyrus@openwrt.org
Pierre Pfister
Cisco Systems
Paris
France
Email: pierre.pfister@darou.fr
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