Internet DRAFT - draft-ietf-pce-pcep-domain-sequence
draft-ietf-pce-pcep-domain-sequence
PCE Working Group D. Dhody
Internet-Draft U. Palle
Intended status: Experimental Huawei Technologies
Expires: June 9, 2016 R. Casellas
CTTC
December 7, 2015
Domain Subobjects for Path Computation Element (PCE) Communication
Protocol (PCEP).
draft-ietf-pce-pcep-domain-sequence-12
Abstract
The ability to compute shortest constrained Traffic Engineering Label
Switched Paths (TE LSPs) in Multiprotocol Label Switching (MPLS) and
Generalized MPLS (GMPLS) networks across multiple domains has been
identified as a key requirement. In this context, a domain is a
collection of network elements within a common sphere of address
management or path computational responsibility such as an Interior
Gateway Protocol (IGP) area or an Autonomous System (AS). This
document specifies a representation and encoding of a Domain-
Sequence, which is defined as an ordered sequence of domains
traversed to reach the destination domain to be used by Path
Computation Elements (PCEs) to compute inter-domain constrained
shortest paths across a predetermined sequence of domains . This
document also defines new subobjects to be used to encode domain
identifiers.
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 June 9, 2016.
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Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Detail Description . . . . . . . . . . . . . . . . . . . . . 6
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Domain-Sequence . . . . . . . . . . . . . . . . . . . . . 6
3.3. Domain-Sequence Representation . . . . . . . . . . . . . 7
3.4. Include Route Object (IRO) . . . . . . . . . . . . . . . 7
3.4.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 8
3.4.1.1. Autonomous system . . . . . . . . . . . . . . . . 8
3.4.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 9
3.4.2. Update in IRO specification . . . . . . . . . . . . . 10
3.4.3. IRO for Domain-Sequence . . . . . . . . . . . . . . . 10
3.4.3.1. PCC Procedures . . . . . . . . . . . . . . . . . 11
3.4.3.2. PCE Procedures . . . . . . . . . . . . . . . . . 11
3.5. Exclude Route Object (XRO) . . . . . . . . . . . . . . . 12
3.5.1. Subobjects . . . . . . . . . . . . . . . . . . . . . 13
3.5.1.1. Autonomous system . . . . . . . . . . . . . . . . 13
3.5.1.2. IGP Area . . . . . . . . . . . . . . . . . . . . 14
3.6. Explicit Exclusion Route Subobject (EXRS) . . . . . . . . 15
3.7. Explicit Route Object (ERO) . . . . . . . . . . . . . . . 16
4. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 16
4.1. Inter-Area Path Computation . . . . . . . . . . . . . . . 16
4.2. Inter-AS Path Computation . . . . . . . . . . . . . . . . 18
4.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 19
4.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 21
4.3. Boundary Node and Inter-AS-Link . . . . . . . . . . . . . 23
4.4. PCE Serving multiple Domains . . . . . . . . . . . . . . 24
4.5. P2MP . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4.6. Hierarchical PCE . . . . . . . . . . . . . . . . . . . . 26
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5. Other Considerations . . . . . . . . . . . . . . . . . . . . 26
5.1. Relationship to PCE Sequence . . . . . . . . . . . . . . 26
5.2. Relationship to RSVP-TE . . . . . . . . . . . . . . . . . 26
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27
6.1. New Subobjects . . . . . . . . . . . . . . . . . . . . . 27
7. Security Considerations . . . . . . . . . . . . . . . . . . . 27
8. Manageability Considerations . . . . . . . . . . . . . . . . 28
8.1. Control of Function and Policy . . . . . . . . . . . . . 28
8.2. Information and Data Models . . . . . . . . . . . . . . . 28
8.3. Liveness Detection and Monitoring . . . . . . . . . . . . 29
8.4. Verify Correct Operations . . . . . . . . . . . . . . . . 29
8.5. Requirements On Other Protocols . . . . . . . . . . . . . 29
8.6. Impact On Network Operations . . . . . . . . . . . . . . 29
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 30
10.1. Normative References . . . . . . . . . . . . . . . . . . 30
10.2. Informative References . . . . . . . . . . . . . . . . . 31
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 33
1. Introduction
A Path Computation Element (PCE) may be used to compute end-to-end
paths across multi-domain environments using a per-domain path
computation technique [RFC5152]. The backward recursive path
computation (BRPC) mechanism [RFC5441] also defines a PCE-based path
computation procedure to compute inter-domain constrained path for
(G)MPLS TE LSPs. However, both per-domain and BRPC techniques assume
that the sequence of domains to be crossed from source to destination
is known, either fixed by the network operator or obtained by other
means. Also for inter-domain point-to-multi-point (P2MP) tree
computation, [RFC7334] assumes the domain-tree is known in priori.
The list of domains (Domain-Sequence) in point-to-point (P2P) or a
domain tree in point-to-multipoint (P2MP) is usually a constraint in
inter-domain path computation procedure.
The Domain-Sequence (the set of domains traversed to reach the
destination domain) is either administratively predetermined or
discovered by some means like H-PCE.
[RFC5440] defines the Include Route Object (IRO) and the Explicit
Route Object (ERO). [RFC5521] defines the Exclude Route Object (XRO)
and the Explicit Exclusion Route Subobject (EXRS). The use of
Autonomous System (AS) (albeit with a 2-Byte AS number) as an
abstract node representing a domain is defined in [RFC3209]. In the
current document, we specify new subobjects to include or exclude
domains including IGP area or an Autonomous Systems (4-Byte as per
[RFC6793]).
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Further, the domain identifier may simply act as delimiter to specify
where the domain boundary starts and ends in some cases.
This is a companion document to Resource ReserVation Protocol -
Traffic Engineering (RSVP-TE) extensions for the domain identifiers
[DOMAIN-SUBOBJ].
1.1. Scope
The procedures described in this document are experimental. The
experiment is intended to enable research for the usage of Domain-
Sequence at the PCEs for inter-domain paths. For this purpose this
document specifies new domain subobjects as well as how they
incorporate with existing subobjects to represent a Domain-Sequence.
The experiment will end two years after the RFC is published. At
that point, the RFC authors will attempt to determine how widely this
has been implemented and deployed.
This document does not change the procedures for handling existing
subobjects in PCEP.
The new subobjects introduced by this document will not be understood
by legacy implementations. If a legacy implementation receives one
of the subobjects that it does not understand in a PCEP object, the
legacy implementation will behave as described in Section 3.4.3.
Therefore, it is assumed that this experiment will be conducted only
when both the PCE and the PCC form part of the experiment. It is
possible that a PCC or PCE can operate with peers some of which form
part of the experiment and some that do not. In this case, since no
capabilities exchange is used to identify which nodes can use these
extensions, manual configuration should be used to determine which
peerings form part of the experiment.
When the result of implementation and deployment are available, this
document will be updated and refined, and then be moved from
Experimental to Standard Track.
1.2. 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].
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2. Terminology
The following terminology is used in this document.
ABR: OSPF Area Border Router. Routers used to connect two IGP
areas.
AS: Autonomous System.
ASBR: Autonomous System Boundary Router.
BN: Boundary Node, Can be an ABR or ASBR.
BRPC: Backward Recursive Path Computation
Domain: As per [RFC4655], any collection of network elements within
a common sphere of address management or path computational
responsibility. Examples of domains include Interior Gateway
Protocol (IGP) area and Autonomous System (AS).
Domain-Sequence: An ordered sequence of domains traversed to reach
the destination domain.
ERO: Explicit Route Object
H-PCE: Hierarchical PCE
IGP: Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (IS-IS).
IRO: Include Route Object
IS-IS: Intermediate System to Intermediate System.
OSPF: Open Shortest Path First.
PCC: Path Computation Client: any client application requesting a
path computation to be performed by a Path Computation Element.
PCE: Path Computation Element. An entity (component, application,
or network node) that is capable of computing a network path or
route based on a network graph and applying computational
constraints.
P2MP: Point-to-Multipoint
P2P: Point-to-Point
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RSVP: Resource Reservation Protocol
TE LSP: Traffic Engineering Label Switched Path.
XRO: Exclude Route Object
3. Detail Description
3.1. Domains
[RFC4726] and [RFC4655] define domain as a separate administrative or
geographic environment within the network. A domain could be further
defined as a zone of routing or computational ability. Under these
definitions a domain might be categorized as an AS or an IGP area.
Each AS can be made of several IGP areas. In order to encode a
Domain-Sequence, it is required to uniquely identify a domain in the
Domain-Sequence. A domain can be uniquely identified by area-id or
AS number or both.
3.2. Domain-Sequence
A Domain-Sequence is an ordered sequence of domains traversed to
reach the destination domain.
A Domain-Sequence can be applied as a constraint and carried in a
path computation request to PCE(s). A Domain-Sequence can also be
the result of a path computation. For example, in the case of
Hierarchical PCE (H-PCE) [RFC6805], Parent PCE could send the Domain-
Sequence as a result in a path computation reply.
In a P2P path, the domains listed appear in the order that they are
crossed. In a P2MP path, the domain tree is represented as a list of
Domain-Sequences.
A Domain-Sequence enables a PCE to select the next domain and the PCE
serving that domain to forward the path computation request based on
the domain information.
Domain-Sequence can include Boundary Nodes (ABR or ASBR) or Border
links (Inter-AS-links) to be traversed as an additional constraint.
Thus a Domain-Sequence can be made up of one or more of -
o AS Number
o Area ID
o Boundary Node ID
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o Inter-AS-Link Address
These are encoded in the new subobjects defined in this document as
well as the existing subobjects to represent a Domain-Sequence.
Consequently, a Domain-Sequence can be used:
1. by a PCE in order to discover or select the next PCE in a
collaborative path computation, such as in BRPC [RFC5441];
2. by the Parent PCE to return the Domain-Sequence when unknown;
this can then be an input to the BRPC procedure [RFC6805];
3. by a Path Computation Client (PCC) or a PCE, to constrain the
domains used in inter-domain path computation, explicitly
specifying which domains to be expanded or excluded;
4. by a PCE in the per-domain path computation model [RFC5152] to
identify the next domain.
3.3. Domain-Sequence Representation
Domain-Sequence appears in PCEP messages, notably in -
o Include Route Object (IRO): As per [RFC5440], IRO can be used to
specify a set of network elements to be traversed to reach the
destination, which includes subobjects used to specify the Domain-
Sequence.
o Exclude Route Object (XRO): As per [RFC5521], XRO can be used to
specify certain abstract nodes, to be excluded from whole path,
which includes subobjects used to specify the Domain-Sequence.
o Explicit Exclusion Route Subobject (EXRS): As per [RFC5521], EXRS
can be used to specify exclusion of certain abstract nodes
(including domains) between a specific pair of nodes. EXRS are a
subobject inside the IRO.
o Explicit Route Object (ERO): As per [RFC5440], ERO can be used to
specify a computed path in the network. For example, in the case
of H-PCE [RFC6805], a Parent PCE can send the Domain-Sequence as a
result, in a path computation reply using ERO.
3.4. Include Route Object (IRO)
As per [RFC5440], IRO (Include Route Object) can be used to specify
that the computed path needs to traverse a set of specified network
elements or abstract nodes.
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3.4.1. Subobjects
Some subobjects are defined in [RFC3209], [RFC3473], [RFC3477] and
[RFC4874], but new subobjects related to Domain-Sequence are needed.
This document extends the support for 4-Byte AS numbers and IGP
Areas.
Type Subobject
TBD1 Autonomous system number (4 Byte)
TBD2 OSPF Area id
TBD3 ISIS Area id
Note: The twins of these subobjects are carried in RSVP-TE messages
as defined in [DOMAIN-SUBOBJ].
3.4.1.1. Autonomous system
[RFC3209] already defines 2 byte AS number.
To support 4 byte AS number as per [RFC6793] following subobject is
defined:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS-ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209]
and usage in IRO subobject updated in [IRO-UPDATE].
Type: (TBD1 by IANA) indicating a 4-Byte AS Number.
Length: 8 (Total length of the subobject in bytes).
Reserved: Zero at transmission, ignored at receipt.
AS-ID: The 4-Byte AS Number. Note that if 2-Byte AS numbers are in
use, the low order bits (16 through 31) MUST be used and the high
order bits (0 through 15) MUST be set to zero.
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3.4.1.2. IGP Area
Since the length and format of Area-id is different for OSPF and
ISIS, following two subobjects are defined:
For OSPF, the area-id is a 32 bit number. The subobject is encoded
as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209]
and usage in IRO subobject updated in [IRO-UPDATE].
Type: (TBD2 by IANA) indicating a 4-Byte OSPF Area ID.
Length: 8 (Total length of the subobject in bytes).
Reserved: Zero at transmission, ignored at receipt.
OSPF Area Id: The 4-Byte OSPF Area ID.
For IS-IS, the area-id is of variable length and thus the length of
the Subobject is variable. The Area-id is as described in IS-IS by
ISO standard [ISO10589]. The subobject is encoded as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
L: The L bit is an attribute of the subobject as defined in [RFC3209]
and usage in IRO subobject updated in [IRO-UPDATE].
Type: (TBD3 by IANA) indicating IS-IS Area ID.
Length: Variable. The Length MUST be at least 8, and MUST be a
multiple of 4.
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Area-Len: Variable (Length of the actual (non-padded) IS-IS Area
Identifier in octets; Valid values are from 1 to 13 inclusive).
Reserved: Zero at transmission, ignored at receipt.
IS-IS Area Id: The variable-length IS-IS area identifier. Padded
with trailing zeroes to a four-byte boundary.
3.4.2. Update in IRO specification
[RFC5440] describes IRO as an optional object used to specify network
elements to be traversed by the computed path. It further state that
the L bit of such subobject has no meaning within an IRO. It also
did not mention if IRO is an ordered or un-ordered list of
subobjects.
An update to IRO specification [IRO-UPDATE] makes IRO as an ordered
list, as well as support for loose bit (L-bit) is added.
The use of IRO for Domain-Sequence, assumes the updated specification
for IRO, as per [IRO-UPDATE].
3.4.3. IRO for Domain-Sequence
The subobject type for IPv4, IPv6, and unnumbered Interface ID can be
used to specify Boundary Nodes (ABR/ASBR) and Inter-AS-Links. The
subobject type for the AS Number (2 or 4 Byte) and the IGP Area are
used to specify the domain identifiers in the Domain-Sequence.
The IRO can incorporate the new domain subobjects with the existing
subobjects in a sequence of traversal.
Thus an IRO, comprising subobjects, that represents a Domain-
Sequence, define the domains involved in an inter-domain path
computation, typically involving two or more collaborative PCEs.
A Domain-Sequence can have varying degrees of granularity. It is
possible to have a Domain-Sequence composed of, uniquely, AS
identifiers. It is also possible to list the involved IGP areas for
a given AS.
In any case, the mapping between domains and responsible PCEs is not
defined in this document. It is assumed that a PCE that needs to
obtain a "next PCE" from a Domain-Sequence is able to do so (e.g. via
administrative configuration, or discovery).
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3.4.3.1. PCC Procedures
A PCC builds an IRO to encode the Domain-Sequence, so that the
cooperating PCEs could compute an inter-domain shortest constrained
path across the specified sequence of domains.
A PCC may intersperse Area and AS subobjects with other subobjects
without change to the previously specified processing of those
subobjects in the IRO.
3.4.3.2. PCE Procedures
If a PCE receives an IRO in a Path Computation request (PCReq)
message that contains the subobjects defined in this document, that
it does not recognize, it will respond according to the rules for a
malformed object as per [RFC5440]. The PCE MAY also include the IRO
in the PCErr message as per [RFC5440].
The interpretation of Loose bit (L bit) is as per section 4.3.3.1 of
[RFC3209] (as per [IRO-UPDATE]).
In a Path Computation reply (PCRep), PCE MAY also supply IRO (with
Domain-Sequence information) with the NO-PATH object indicating that
the set of elements (domains) of the request's IRO prevented the PCEs
from finding a path.
The following processing rules apply for Domain-Sequence in IRO -
o When a PCE parses an IRO, it interprets each subobject according
to the AS number associated with the preceding subobject. We call
this the "current AS". Certain subobjects modify the current AS,
as follows.
* The current AS is initialized to the AS number of the PCC.
* If the PCE encounters an AS subobject, then it updates the
current AS to this new AS number.
* If the PCE encounters an Area subobject, then it assumes that
the area belongs to the current AS.
* If the PCE encounters an IP address that is globally routable,
then it updates the current AS to the AS that owns this IP
address. This document does not define how the PCE learns
which AS owns the IP address.
* If the PCE encounters an IP address that is not globally
routable, then it assumes that it belongs to the current AS.
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* If the PCE encounters an unnumbered link, then it assumes that
it belongs to the current AS.
o When a PCE parses an IRO, it interprets each subobject according
to the Area ID associated with the preceding subobject. We call
this the "current Area". Certain subobjects modify the current
Area, as follows.
* The current Area is initialized to the Area ID of the PCC.
* If the current AS is changed, the current Area is reset and
need to be determined again by current or subsequent subobject.
* If the PCE encounters an Area subobject, then it updates the
current Area to this new Area ID.
* If the PCE encounters an IP address that belongs to a different
area, then it updates the current Area to the Area that has
this IP address. This document does not define how the PCE
learns which Area has the IP address.
* If the PCE encounters an unnumbered link that belongs to a
different area, then it updates the current Area to the Area
that has this link.
* Otherwise, it assumes that the subobject belongs to the current
Area.
o In case the current PCE is not responsible for the path
computation in the current AS or Area, then the PCE selects the
"next PCE" in the domain-sequence based on the current AS and
Area.
Note that it is advised that, PCC should use AS and Area subobject
while building the domain-sequence in IRO and avoid using other
mechanism to change the "current AS" and "current Area" as described
above.
3.5. Exclude Route Object (XRO)
The Exclude Route Object (XRO) [RFC5521] is an optional object used
to specify exclusion of certain abstract nodes or resources from the
whole path.
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3.5.1. Subobjects
Some subobjects to be used in XRO as defined in [RFC3209], [RFC3477],
[RFC4874], and [RFC5520], but new subobjects related to Domain-
Sequence are needed.
This document extends the support for 4-Byte AS numbers and IGP
Areas.
Type Subobject
TBD1 Autonomous system number (4 Byte)
TBD2 OSPF Area id
TBD3 ISIS Area id
Note: The twins of these subobjects are carried in RSVP-TE messages
as defined in [DOMAIN-SUBOBJ].
3.5.1.1. Autonomous system
The new subobjects to support 4 byte AS and IGP (OSPF / ISIS) Area
MAY also be used in the XRO to specify exclusion of certain domains
in the path computation procedure.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS-ID (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
0: indicates that the AS specified MUST be excluded from the path
computed by the PCE(s).
1: indicates that the AS specified SHOULD be avoided from the inter-
domain path computed by the PCE(s), but MAY be included subject to
PCE policy and the absence of a viable path that meets the other
constraints.
All other fields are consistent with the definition in Section 3.4.
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3.5.1.2. IGP Area
Since the length and format of Area-id is different for OSPF and
ISIS, following two subobjects are defined:
For OSPF, the area-id is a 32 bit number. The subobject is encoded
as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OSPF Area Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
0: indicates that the OSFF Area specified MUST be excluded from the
path computed by the PCE(s).
1: indicates that the OSFF Area specified SHOULD be avoided from the
inter-domain path computed by the PCE(s), but MAY be included
subject to PCE policy and the absence of a viable path that meets
the other constraints.
All other fields are consistent with the definition in Section 3.4.
For IS-IS, the area-id is of variable length and thus the length of
the subobject is variable. The Area-id is as described in IS-IS by
ISO standard [ISO10589]. The subobject is encoded as follows:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|X| Type | Length | Area-Len | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// IS-IS Area ID //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The X-bit indicates whether the exclusion is mandatory or desired.
0: indicates that the ISIS Area specified MUST be excluded from the
path computed by the PCE(s).
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1: indicates that the ISIS Area specified SHOULD be avoided from the
inter-domain path computed by the PCE(s), but MAY be included
subject to PCE policy and the absence of a viable path that meets
the other constraints.
All other fields are consistent with the definition in Section 3.4.
All the processing rules are as per [RFC5521].
Note that, if a PCE receives an XRO in a PCReq message that contains
subobjects defined in this document, that it does not recognize, it
will respond according to the rules for a malformed object as per
[RFC5440].
IGP Area subobjects in the XRO are local to the current AS. In case
of multi-AS path computation to exclude an IGP area in a different
AS, IGP Area subobject should be part of Explicit Exclusion Route
Subobject (EXRS) in the IRO to specify the AS in which the IGP area
is to be excluded. Further policy may be applied to prune/ignore
Area subobjects in XRO after "current AS" change during path
computation.
3.6. Explicit Exclusion Route Subobject (EXRS)
EXRS [RFC5521] is used to specify exclusion of certain abstract nodes
between a specific pair of nodes.
The EXRS subobject can carry any of the subobjects defined for
inclusion in the XRO, thus the new subobjects to support 4 byte AS
and IGP (OSPF / ISIS) Area can also be used in the EXRS. The
meanings of the fields of the new XRO subobjects are unchanged when
the subobjects are included in an EXRS, except that scope of the
exclusion is limited to the single hop between the previous and
subsequent elements in the IRO.
The EXRS subobject should be interpreted in the context of the
current AS and current Area of the preceding subobject in the IRO.
The EXRS subobject does not change the current AS or current Area.
All other processing rules are as per [RFC5521].
Note that, if a PCE that supports the EXRS in an IRO, parses an IRO,
and encounters an EXRS that contains subobjects defined in this
document, that it does not recognize, it will act according to the
setting of the X-bit in the subobject as per [RFC5521].
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3.7. Explicit Route Object (ERO)
The Explicit Route Object (ERO) [RFC5440] is used to specify a
computed path in the network. PCEP ERO subobject types correspond to
RSVP-TE ERO subobject types as defined in [RFC3209], [RFC3473],
[RFC3477], [RFC4873], [RFC4874], and [RFC5520]. The subobjects
related to Domain-Sequence are further defined in [DOMAIN-SUBOBJ].
The new subobjects to support 4 byte AS and IGP (OSPF / ISIS) Area
can also be used in the ERO to specify an abstract node (a group of
nodes whose internal topology is opaque to the ingress node of the
LSP). Using this concept of abstraction, an explicitly routed LSP
can be specified as a sequence of domains.
In case of Hierarchical PCE [RFC6805], a Parent PCE can be requested
to find the Domain-Sequence. Refer example in Section 4.6. The ERO
in reply from parent PCE can then be used in Per-Domain path
computation or BRPC.
If a PCC receives an ERO in a PCRep message that contains subobject
defined in this document, that it does not recognize, it will respond
according to the rules for a malformed object as per [RFC5440].
4. Examples
The examples in this section are for illustration purposes only; to
highlight how the new subobjects could be encoded. They are not
meant to be an exhaustive list of all possible usecases and
combinations.
4.1. Inter-Area Path Computation
In an inter-area path computation where the ingress and the egress
nodes belong to different IGP areas within the same AS, the Domain-
Sequence could be represented using a ordered list of Area
subobjects.
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----------------- -----------------
| | | |
| +--+ | | +--+ |
| +--+ | | | | | | |
| | | +--+ | | +--+ +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | -------------------------- | +--+ |
| +--+ +--+ |
| | | +--+ | | |
|Area 2 +--+ | | +--+ Area 4 |
----------------- | +--+ | -----------------
| |
| +--+ |
| +--+ | | |
| | | +--+ |
| +--+ |
| |
| |
| |
| |
| +--+ |
| | | |
| +--+ |
----------------- | | ------------------
| +--+ +--+ |
| | | | | |
| +--+ Area 0 +--+ |
| | -------------------------- | +--+ |
| +--+ | | | | |
| | | | | +--+ |
| +--+ +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| +--+ | | |
| | | | | +--+ |
| +--+ | | | | |
| | | +--+ |
| | | |
| Area 1 | | Area 5 |
----------------- ------------------
Figure 1: Inter-Area Path Computation
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AS Number is 100.
If the ingress is in Area 2, egress in Area 4 and transit through
Area 0. Some possible way a PCC can encode the IRO:
+---------+ +---------+ +---------+
|IRO | |Sub | |Sub |
|Object | |Object | |Object |
|Header | |Area 0 | |Area 4 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
or
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object |
|Header | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
or
+---------+ +---------+ +---------+ +---------+ +---------+
|IRO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object AS| |Object | |Object | |Object |
|Header | |100 | |Area 2 | |Area 0 | |Area 4 |
| | | | | | | | | |
| | | | | | | | | |
+---------+ +---------+ +---------+ +---------+ +---------+
The Domain-Sequence can further include encompassing AS information
in the AS subobject.
4.2. Inter-AS Path Computation
In inter-AS path computation, where ingress and egress belong to
different AS, the Domain-Sequence could be represented using an
ordered list of AS subobjects. The Domain-Sequence can further
include decomposed area information in the Area subobject.
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4.2.1. Example 1
As shown in Figure 2, where AS has a single area, AS subobject in the
domain-sequence can uniquely identify the next domain and PCE.
AS A AS E AS C
<-------------> <----------> <------------->
A4----------E1---E2---E3---------C4
/ / \
/ / \
/ / AS B \
/ / <----------> \
Ingress------A1---A2------B1---B2---B3------C1---C2------Egress
\ / /
\ / /
\ / /
\ / /
A3----------D1---D2---D3---------C3
<---------->
AS D
* All AS have one area (area 0)
Figure 2: Inter-AS Path Computation
If the ingress is in AS A, egress in AS C and transit through AS B.
Some possible way a PCC can encode the IRO:
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+-------+ +-------+ +-------+
|IRO | |Sub | |Sub |
|Object | |Object | |Object |
|Header | |AS B | |AS C |
| | | | | |
+-------+ +-------+ +-------+
or
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object |
|Header | |AS A | |AS B | |AS C |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object | |Object | |Object | |Object |
|Header | |AS A | |Area 0 | |AS B | |Area 0 | |AS C | |Area 0 |
| | | | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+ +-------+
Note that to get a domain disjoint path, the ingress could also
request the backup path with -
+-------+ +-------+
|XRO | |Sub |
|Object | |Object |
|Header | |AS B |
| | | |
+-------+ +-------+
As described in Section 3.4.3, domain subobject in IRO changes the
domain information associated with the next set of subobjects; till
you encounter a subobject that changes the domain too. Consider the
following IRO:
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object | |Object | |Object |
|Header | |AS B | |IP | |IP | |AS C | |IP |
| | | | |B1 | |B3 | | | |C1 |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
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On processing subobject "AS B", it changes the AS of the subsequent
subobjects till we encounter another subobject "AS C" which changes
the AS for its subsequent subobjects.
Consider another IRO:
+-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object | |Object |
|Header | |AS D | |IP | |IP | |IP |
| | | | |D1 | |D3 | |C3 |
+-------+ +-------+ +-------+ +-------+ +-------+
Here as well, on processing "AS D", it changes the AS of the
subsequent subobjects till you encounter another subobject "C3" which
belong in another AS and changes the AS for its subsequent
subobjects.
Further description for the Boundary Node and Inter-AS-Link can be
found in Section 4.3.
4.2.2. Example 2
In Figure 3, AS 200 is made up of multiple areas.
|
| +-------------+ +----------------+
| |Area 2 | |Area 4 |
| | +--+| | +--+ |
| | | || | | B| |
| | +--+ +--+| | +--+ +--+ |
| | | | | | | | |
| | +--+ | | +--+ |
| | +--+ | | +--+ |
| | | | | | | | |
| | +--+ | | +--+ +--+ |
| | +--+ |+--------------+| | | |
| | | | +--+ +--+ +--+ |
+-------------+| | +--+ | | | | |
| || | +--+ +--+ |
| +--+|| +-------------+| |+----------------+
| | ||| | +--+ |
| +--+|| | | | |
| +--+ || | +--+ |
| | | +---+ +--+ |
| +--+ | |----------------| | |
| +---+ Inter-AS +--+ +--+ |
|+--+ || Links | | | |
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||A | +---+ +--+ +--+ |
|+--+ | |----------------| | |
| +---+ +--+ +--+ |
| +--+ || +------------+ | | | |+----------------+
| | | || |Area 3 +--+ +--+ +--+ Area 5 |
| +--+ || | | | | | |
| || | +--+ +--+ |
| +--+|| | +--+ | | Area 0 || +--+ |
| | ||| | | | | +--------------+| | | |
| +--+|| | +--+ | | +--+ |
| || | | | +--+ |
|Area 0 || | +--+ | | +--+ | | |
+-------------+| | | | | | | | +--+ |
| | +--+ +--+ | +--+ |
| | | | | |
| | +--+ | +--+ |
| | +--+ | | | C| |
| | | | | | +--+ |
| | +--+ | | |
| | | | |
| +------------+ +----------------+
|
|
AS 100 | AS 200
|
Figure 3: Inter-AS Path Computation
For LSP (A-B), where ingress A is in (AS 100, Area 0), egress B in
(AS 200, Area 4) and transit through (AS 200, Area 0). Some possible
way a PCC can encode the IRO:
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object |
|Header | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object | |Object | |Object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 4 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
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For LSP (A-C), where ingress A is in (AS 100, Area 0), egress C in
(AS 200, Area 5) and transit through (AS 200, Area 0). Some possible
way a PCC can encode the IRO:
+-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object |
|Header | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | |
+-------+ +-------+ +-------+ +-------+
or
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
|IRO | |Sub | |Sub | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object | |Object | |Object |
|Header | |AS 100 | |Area 0 | |AS 200 | |Area 0 | |Area 5 |
| | | | | | | | | | | |
+-------+ +-------+ +-------+ +-------+ +-------+ +-------+
4.3. Boundary Node and Inter-AS-Link
A PCC or PCE can include additional constraints covering which
Boundary Nodes (ABR or ASBR) or Border links (Inter-AS-link) to be
traversed while defining a Domain-Sequence. In which case the
Boundary Node or Link can be encoded as a part of the Domain-
Sequence.
Boundary Nodes (ABR / ASBR) can be encoded using the IPv4 or IPv6
prefix subobjects usually the loopback address of 32 and 128 prefix
length respectively. An Inter-AS link can be encoded using the IPv4
or IPv6 prefix subobjects or unnumbered interface subobjects.
For Figure 1, an ABR (say 203.0.113.1) to be traversed can be
specified in IRO as:
+---------+ +---------+ +---------++---------+ +---------+
|IRO | |Sub | |Sub ||Sub | |Sub |
|Object | |Object | |Object ||Object | |Object |
|Header | |Area 2 | |IPv4 ||Area 0 | |Area 4 |
| | | | |203.0. || | | |
| | | | |112.1 || | | |
+---------+ +---------+ +---------++---------+ +---------+
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For Figure 3, an inter-AS-link (say 198.51.100.1 - 198.51.100.2) to
be traversed can be specified as:
+---------+ +---------+ +---------+ +---------+
|IRO | |Sub | |Sub | |Sub |
|Object | |Object AS| |Object | |Object AS|
|Header | |100 | |IPv4 | |200 |
| | | | |198.51. | | |
| | | | |100.2 | | |
+---------+ +---------+ +---------+ +---------+
4.4. PCE Serving multiple Domains
A single PCE can be responsible for multiple domains; for example PCE
function deployed on an ABR could be responsible for multiple areas.
A PCE which can support adjacent domains can internally handle those
domains in the Domain-Sequence without any impact on the other
domains in the Domain-Sequence.
4.5. P2MP
[RFC7334] describes an experimental inter-domain P2MP path
computation mechanism where the path domain tree is described as a
series of Domain-Sequences, an example is shown in the below figure:
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+----------------+
| |Domain D1
| R |
| |
| A |
| |
+-B------------C-+
/ \
/ \
/ \
Domain D2 / \ Domain D3
+-------------D--+ +-----E----------+
| | | |
| F | | |
| G | | H |
| | | |
| | | |
+-I--------------+ +-J------------K-+
/\ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ \ / \
/ Domain D4 \ Domain D5 / Domain D6 \
+-L-------------W+ +------P---------+ +-----------T----+
| | | | | |
| | | Q | | U |
| M O | | S | | |
| | | | | V |
| N | | R | | |
+----------------+ +----------------+ +----------------+
The domain tree can be represented as a series of domain-sequence -
o Domain D1, Domain D3, Domain D6
o Domain D1, Domain D3, Domain D5
o Domain D1, Domain D2, Domain D4
The domain sequence handling described in this document could be
applied to P2MP path domain tree.
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4.6. Hierarchical PCE
In case of H-PCE [RFC6805], the parent PCE can be requested to
determine the Domain-Sequence and return it in the path computation
reply, using the ERO. . For the example in section 4.6 of [RFC6805],
the Domain-Sequence can possibly appear as:
+---------+ +---------+ +---------+ +---------+
|ERO | |Sub | |Sub | |Sub |
|Object | |Object | |Object | |Object |
|Header | |Domain 1 | |Domain 2 | |Domain 3 |
| | | | | | | |
| | | | | | | |
+---------+ +---------+ +---------+ +---------+
or
+---------+ +---------+ +---------+
|ERO | |Sub | |Sub |
|Object | |Object | |Object |
|Header | |BN 21 | |Domain 3 |
| | | | | |
| | | | | |
+---------+ +---------+ +---------+
5. Other Considerations
5.1. Relationship to PCE Sequence
Instead of a Domain-Sequence, a sequence of PCEs MAY be enforced by
policy on the PCC, and this constraint can be carried in the PCReq
message (as defined in [RFC5886]).
Note that PCE-Sequence can be used along with Domain-Sequence in
which case PCE-Sequence MUST have higher precedence in selecting the
next PCE in the inter-domain path computation procedures.
5.2. Relationship to RSVP-TE
[RFC3209] already describes the notion of abstract nodes, where an
abstract node is a group of nodes whose internal topology is opaque
to the ingress node of the LSP. It further defines a subobject for
AS but with a 2-Byte AS Number.
[DOMAIN-SUBOBJ] extends the notion of abstract nodes by adding new
subobjects for IGP Areas and 4-byte AS numbers. These subobjects can
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be included in Explicit Route Object (ERO), Exclude Route object
(XRO) or Explicit Exclusion Route Subobject (EXRS) in RSVP-TE.
In any case subobject type defined in RSVP-TE are identical to the
subobject type defined in the related documents in PCEP.
6. IANA Considerations
6.1. New Subobjects
IANA maintains the "Path Computation Element Protocol (PCEP) Numbers"
at <http://www.iana.org/assignments/pcep>. Within this registry IANA
maintains two sub-registries:
o IRO Subobjects (see IRO Subobjects at
http://www.iana.org/assignments/pcep)
o XRO Subobjects (see XRO Subobjects at
http://www.iana.org/assignments/pcep)
Upon approval of this document, IANA is requested to make identical
additions to these registries as follows:
Subobject Type Reference
TBD1 4 byte AS number [This I.D.][DOMAIN-SUBOBJ]
TBD2 OSPF Area ID [This I.D.][DOMAIN-SUBOBJ]
TBD3 IS-IS Area ID [This I.D.][DOMAIN-SUBOBJ]
Further upon approval of this document, IANA is requested to add a
reference to this document to the new RSVP numbers that are
registered by [DOMAIN-SUBOBJ].
7. Security Considerations
The protocol extensions defined in this document do not substantially
change the nature of PCEP. Therefore, the security considerations
set out in [RFC5440] apply unchanged. Note that further security
considerations for the use of PCEP over TCP are presented in
[RFC6952].
This document specifies a representation of Domain-Sequence and new
subobjects, which could be used in inter-domain PCE scenarios as
explained in [RFC5152], [RFC5441], [RFC6805], [RFC7334] etc. The
security considerations set out in each of these mechanisms remain
unchanged by the new subobjects and Domain-Sequence representation in
this document.
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But the new subobjects do allow finer and more specific control of
the path computed by a cooperating PCE(s). Such control increases
the risk if a PCEP message is intercepted, modified, or spoofed
because it allows the attacker to exert control over the path that
the PCE will compute or to make the path computation impossible.
Consequently, it is important that implementations conform to the
relevant security requirements of [RFC5440]. These mechanisms
include:
o Securing the PCEP session messages using TCP security techniques
(Section 10.2 of [RFC5440]). PCEP implementations SHOULD also
consider the additional security provided by the TCP
Authentication Option (TCP-AO) [RFC5925] or [PCEPS].
o Authenticating the PCEP messages to ensure the message is intact
and sent from an authorized node (Section 10.3 of [RFC5440]).
o PCEP operates over TCP, so it is also important to secure the PCE
and PCC against TCP denial-of-service attacks. Section 10.7.1 of
[RFC5440] outlines a number of mechanisms for minimizing the risk
of TCP-based denial-of-service attacks against PCEs and PCCs.
o In inter-AS scenarios, attacks may be particularly significant
with commercial as well as service-level implications.
Note, however, that the Domain-Sequence mechanisms also provide the
operator with the ability to route around vulnerable parts of the
network and may be used to increase overall network security.
8. Manageability Considerations
8.1. Control of Function and Policy
The exact behaviour with regards to desired inclusion and exclusion
of domains MUST be available for examination by an operator and MAY
be configurable. Manual configurations is needed to identify which
PCEP peers understand the new domain subobjects defined in this
document.
8.2. Information and Data Models
A MIB module for management of the PCEP is being specified in a
separate document [RFC7420]. This document does not imply any new
extension to the current MIB module.
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8.3. Liveness Detection and Monitoring
Mechanisms defined in this document do not imply any new liveness
detection and monitoring requirements in addition to those already
listed in [RFC5440].
8.4. Verify Correct Operations
Mechanisms defined in this document do not imply any new operation
verification requirements in addition to those already listed in
[RFC5440].
8.5. Requirements On Other Protocols
In case of per-domain path computation [RFC5152], where the full path
of an inter-domain TE LSP cannot be, or is not determined at the
ingress node, a signaling message can use the domain identifiers.
The Subobjects defined in this document SHOULD be supported by RSVP-
TE. [DOMAIN-SUBOBJ] extends the notion of abstract nodes by adding
new subobjects for IGP Areas and 4-byte AS numbers.
Apart from this, mechanisms defined in this document do not imply any
requirements on other protocols in addition to those already listed
in [RFC5440].
8.6. Impact On Network Operations
The mechanisms described in this document can provide the operator
with the ability to exert finer and more specific control of the path
computation by inclusion or exclusion of domain subobjects. There
may be some scaling benefit when a single domain subobject may
substitute for many subobjects and can reduce the overall message
size and processing.
Backward compatibility issues associated with the new subobjects
arise when a PCE does not recognize them, in which case PCE responds
according to the rules for a malformed object as per [RFC5440]. For
successful operations the PCEs in the network would need to be
upgraded.
9. Acknowledgments
Authors would like to especially thank Adrian Farrel for his detailed
reviews as well as providing text to be included in the document.
Further, we would like to thank Pradeep Shastry, Suresh Babu, Quintin
Zhao, Fatai Zhang, Daniel King, Oscar Gonzalez, Chen Huaimo,
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Venugopal Reddy, Reeja Paul, Sandeep Boina, Avantika Sergio Belotti
and Jonathan Hardwick for their useful comments and suggestions.
Thanks to Jonathan Hardwick for shepherding this document.
Thanks to Deborah Brungard for being the Responsible AD.
Thanks to Amanda Baber for IANA Review.
Thanks to Joel Halpern for Gen-ART Review.
Thanks to Klaas Wierenga for SecDir Review.
Thanks to Spencer Dawkins and Barry Leiba for comments during the
IESG Review.
10. References
10.1. Normative References
[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>.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001,
<http://www.rfc-editor.org/info/rfc3209>.
[RFC3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
DOI 10.17487/RFC3473, January 2003,
<http://www.rfc-editor.org/info/rfc3473>.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003,
<http://www.rfc-editor.org/info/rfc3477>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009,
<http://www.rfc-editor.org/info/rfc5440>.
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[RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux,
"A Backward-Recursive PCE-Based Computation (BRPC)
Procedure to Compute Shortest Constrained Inter-Domain
Traffic Engineering Label Switched Paths", RFC 5441,
DOI 10.17487/RFC5441, April 2009,
<http://www.rfc-editor.org/info/rfc5441>.
[RFC5521] Oki, E., Takeda, T., and A. Farrel, "Extensions to the
Path Computation Element Communication Protocol (PCEP) for
Route Exclusions", RFC 5521, DOI 10.17487/RFC5521, April
2009, <http://www.rfc-editor.org/info/rfc5521>.
[RFC6805] King, D., Ed. and A. Farrel, Ed., "The Application of the
Path Computation Element Architecture to the Determination
of a Sequence of Domains in MPLS and GMPLS", RFC 6805,
DOI 10.17487/RFC6805, November 2012,
<http://www.rfc-editor.org/info/rfc6805>.
[ISO10589]
ISO, "Intermediate system to Intermediate system routing
information exchange protocol for use in conjunction with
the Protocol for providing the Connectionless-mode Network
Service (ISO 8473)", ISO/IEC 10589:2002, 1992.
[IRO-UPDATE]
Dhody, D., "Update to Include Route Object (IRO)
specification in Path Computation Element communication
Protocol (PCEP. (draft-ietf-pce-iro-update-02)", May 2015.
[DOMAIN-SUBOBJ]
Dhody, D., Palle, U., Kondreddy, V., and R. Casellas,
"Domain Subobjects for Resource ReserVation Protocol -
Traffic Engineering (RSVP-TE). (draft-ietf-teas-rsvp-te-
domain-subobjects-05)", November 2015.
10.2. Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006,
<http://www.rfc-editor.org/info/rfc4655>.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for
Inter-Domain Multiprotocol Label Switching Traffic
Engineering", RFC 4726, DOI 10.17487/RFC4726, November
2006, <http://www.rfc-editor.org/info/rfc4726>.
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[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, DOI 10.17487/RFC4873,
May 2007, <http://www.rfc-editor.org/info/rfc4873>.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
Extension to Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE)", RFC 4874, DOI 10.17487/RFC4874,
April 2007, <http://www.rfc-editor.org/info/rfc4874>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Per-Domain Path Computation Method for Establishing Inter-
Domain Traffic Engineering (TE) Label Switched Paths
(LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<http://www.rfc-editor.org/info/rfc5152>.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain Path
Computation Using a Path-Key-Based Mechanism", RFC 5520,
DOI 10.17487/RFC5520, April 2009,
<http://www.rfc-editor.org/info/rfc5520>.
[RFC5886] Vasseur, JP., Ed., Le Roux, JL., and Y. Ikejiri, "A Set of
Monitoring Tools for Path Computation Element (PCE)-Based
Architecture", RFC 5886, DOI 10.17487/RFC5886, June 2010,
<http://www.rfc-editor.org/info/rfc5886>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <http://www.rfc-editor.org/info/rfc5925>.
[RFC6793] Vohra, Q. and E. Chen, "BGP Support for Four-Octet
Autonomous System (AS) Number Space", RFC 6793,
DOI 10.17487/RFC6793, December 2012,
<http://www.rfc-editor.org/info/rfc6793>.
[RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP, and MSDP Issues According to the Keying
and Authentication for Routing Protocols (KARP) Design
Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013,
<http://www.rfc-editor.org/info/rfc6952>.
[RFC7334] Zhao, Q., Dhody, D., King, D., Ali, Z., and R. Casellas,
"PCE-Based Computation Procedure to Compute Shortest
Constrained Point-to-Multipoint (P2MP) Inter-Domain
Traffic Engineering Label Switched Paths", RFC 7334,
DOI 10.17487/RFC7334, August 2014,
<http://www.rfc-editor.org/info/rfc7334>.
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[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., and J.
Hardwick, "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module",
RFC 7420, DOI 10.17487/RFC7420, December 2014,
<http://www.rfc-editor.org/info/rfc7420>.
[PCEPS] Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps-06 (work in
progress), November 2015.
Authors' Addresses
Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: dhruv.ietf@gmail.com
Udayasree Palle
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: udayasree.palle@huawei.com
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
EMail: ramon.casellas@cttc.es
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