Internet DRAFT - draft-ietf-teas-rsvp-te-domain-subobjects
draft-ietf-teas-rsvp-te-domain-subobjects
TEAS Working Group D. Dhody
Internet-Draft U. Palle
Intended status: Experimental V. Kondreddy
Expires: May 22, 2016 Huawei Technologies
R. Casellas
CTTC
November 19, 2015
Domain Subobjects for Resource ReserVation Protocol - Traffic
Engineering (RSVP-TE)
draft-ietf-teas-rsvp-te-domain-subobjects-05
Abstract
The Resource ReserVation Protocol - Traffic Engineering (RSVP-TE)
specification and the Generalized Multiprotocol Label Switching
(GMPLS) extensions to RSVP-TE allow abstract nodes and resources to
be explicitly included in a path setup. Further Exclude Routes
extensions to RSVP-TE allow abstract nodes and resources to be
explicitly excluded in a path setup.
This document specifies new subobjects to include or exclude 4-Byte
Autonomous System (AS) and Interior Gateway Protocol (IGP) area
during path setup.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Task Force (IETF). Note that other groups may also distribute
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This Internet-Draft will expire on May 22, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Subobjects for Domains . . . . . . . . . . . . . . . . . . . 5
3.1. Domains . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Explicit Route Object (ERO)'s Subobjects . . . . . . . . 5
3.2.1. Autonomous system . . . . . . . . . . . . . . . . . . 6
3.2.2. IGP Area . . . . . . . . . . . . . . . . . . . . . . 7
3.2.3. Mode of Operation . . . . . . . . . . . . . . . . . . 8
3.3. Exclude Route Object (XRO)'s Subobjects . . . . . . . . . 8
3.3.1. Autonomous system . . . . . . . . . . . . . . . . . . 8
3.3.2. IGP Area . . . . . . . . . . . . . . . . . . . . . . 9
3.3.3. Mode of Operation . . . . . . . . . . . . . . . . . . 9
3.4. Explicit Exclusion Route Subobject . . . . . . . . . . . 9
4. Interaction with Path Computation Element (PCE) . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
5.1. New Subobjects . . . . . . . . . . . . . . . . . . . . . 10
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
8.2. Informative References . . . . . . . . . . . . . . . . . 12
Appendix A. Examples . . . . . . . . . . . . . . . . . . . . . . 14
A.1. Inter-Area LSP Path Setup . . . . . . . . . . . . . . . . 14
A.2. Inter-AS LSP Path Setup . . . . . . . . . . . . . . . . . 15
A.2.1. Example 1 . . . . . . . . . . . . . . . . . . . . . . 15
A.2.2. Example 2 . . . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
1. Introduction
The RSVP-TE specification [RFC3209] and the GMPLS extensions to RSVP-
TE [RFC3473] allow abstract nodes and resources to be explicitly
included in a path setup using the Explicit Route Object (ERO).
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Further Exclude Routes extensions [RFC4874] allow abstract nodes or
resources to be excluded from the whole path using the Exclude Route
object (XRO). To exclude certain abstract nodes or resources between
a specific pair of abstract nodes present in an ERO, a Explicit
Exclusion Route Subobject (EXRS) is used.
[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 Label Switched Path (LSP). It further
defines a subobject for AS, but with a 2-Byte AS number only.
This document extends the notion of abstract nodes by adding new
subobjects for IGP Areas and 4-byte AS numbers (as per [RFC6793]).
These subobjects can be included in Explicit Route Object (ERO),
Exclude Route Object (XRO) or Explicit Exclusion Route Subobject
(EXRS).
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, and signaling message could use domain identifiers.
The use of these new subobjects is illustrated in Appendix A.
Further, the domain identifier could simply act as delimiter to
specify where the domain boundary starts and ends.
This is a companion document to Path Computation Element Protocol
(PCEP) extensions for the domain sequence [PCE-DOMAIN].
1.1. Scope
The procedures described in this document are experimental. The
experiment is intended to enable research for the usage of Domain
subobjects for inter-domain path setup. For this purpose this
document specify new domain subobjects as well as how they
incorporate with existing subobjects.
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 subobjects
in RSVP-TE.
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 an RSVP-TE object,
the legacy implementation will behave as described in [RFC3209] and
[RFC4874]. Therefore, it is assumed that this experiment will be
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conducted only when all nodes processing the new subobject 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.
It should be noted that there are other ways such as use of boundary
node to identify the domain (instead of domain identifier), the
mechanism defined in this document is just another tool in the
toolkit for the operator.
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].
2. Terminology
The following terminology is used in this document.
AS: Autonomous System.
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) areas and Autonomous Systems (ASs).
ERO: Explicit Route Object
EXRS: Explicit Exclusion Route Subobject
IGP: Interior Gateway Protocol. Either of the two routing
protocols, Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (IS-IS).
IS-IS: Intermediate System to Intermediate System.
OSPF: Open Shortest Path First.
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.
PCEP: Path Computation Element Protocol.
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RSVP: Resource Reservation Protocol
TE LSP: Traffic Engineering Label Switched Path.
XRO: Exclude Route Object
3. Subobjects for Domains
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.
As per [RFC3209], an abstract node is 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 IP prefixes or a sequence of Autonomous Systems. In
this document we extend the notion to include IGP area and 4-Byte AS
number.
These sub-objects appear in RSVP-TE, notably in -
o Explicit Route Object (ERO): As per [RFC3209], an explicit route
is a particular path in the network topology including abstract
nodes (including domains).
o Exclude Route Object (XRO): As per [RFC4874], an exclude route
identifies a list of abstract nodes (including domains), that
should not be traversed along the path of the LSP being
established.
o Explicit Exclusion Route Subobject (EXRS): As per [RFC4874], used
to specify exclusion of certain abstract nodes between a specific
pair of nodes. EXRS are a subobject carried inside the ERO.
These subobjects can be used to specify the domains to be excluded
between two abstract nodes.
3.2. Explicit Route Object (ERO)'s Subobjects
As stated in [RFC3209], an explicit route is a particular path in the
network topology. In addition to the ability to identify specific
nodes along the path, an explicit route can identify a group of nodes
(abstract nodes) to be traversed along the path.
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Some subobjects are defined in [RFC3209], [RFC3473], [RFC3477],
[RFC4874] and [RFC5553] but new subobjects related to domains 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
3.2.1. Autonomous system
[RFC3209] already defines 2-Byte AS number.
To support 4-Byte AS numbers as per [RFC6793], the 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], i.e., set if the subobject represents a loose hop in
the explicit route. If the bit is not set, the subobject
represents a strict hop in the explicit route.
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. For the purpose of
this experiment, it is advised to use 4-Byte AS number subobject
as default.
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3.2.2. IGP Area
Since the length and format of Area-id is different for OSPF and
ISIS, the 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].
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].
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.
3.2.3. Mode of Operation
The new subobjects to support 4-Byte AS and IGP (OSPF / ISIS) Area
could 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).
All the rules of processing (for example Next Hop Selection, L bit
processing, unrecognized subobjects etc) are as per the [RFC3209].
Note that if a node is called upon to process subobject defined in
this document, and it does not recognize, it will behave as described
in [RFC3209] when an unrecognized ERO subobject is encountered. This
means that this node will return a PathErr with error code "Routing
Error" and error value "Bad EXPLICIT_ROUTE object" with the
EXPLICIT_ROUTE object included, truncated (on the left) to the
offending subobject.
3.3. Exclude Route Object (XRO)'s Subobjects
As stated in [RFC4874], the exclude route identifies a list of
abstract nodes that to exclude (not be traversed) along the path of
the LSP being established.
Some subobjects are defined in [RFC3209], [RFC3477], [RFC4874] and
[RFC6001] but new subobjects related to domains 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
3.3.1. Autonomous system
[RFC3209] and [RFC4874] already define a 2-Byte AS number.
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To support 4-Byte AS numbers as per [RFC6793], a subobject is with
the same format as defined in Section 3.2.1 with following
difference:
The meaning of the L bit is as per [RFC4874], where.
0: indicates that the abstract node specified MUST be excluded.
1: indicates that the abstract node specified SHOULD be avoided.
3.3.2. IGP Area
Since the length and format of Area-id is different for OSPF and
ISIS, the following two subobjects are defined:
For OSPF, the area-id is a 32 bit number. Subobjects for OSPF and
IS-IS are of the same format as defined in Section 3.2.2 with
following difference:
The meaning of the L bit is as per [RFC4874].
3.3.3. Mode of Operation
The new subobjects to support 4-Byte AS and IGP (OSPF / ISIS) Area
could also be used in the XRO to specify exclusion of an abstract
node (a group of nodes whose internal topology is opaque to the
ingress node of the LSP).
All the rules of processing are as per the [RFC4874].
Note that if a node is called upon to process a subobject defined in
this document, and it does not recognize, it will behave as described
in [RFC4874] when an unrecognized XRO subobject is encountered, i.e.
to ignore it. In this case the desired exclusion will not be carried
out.
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 ERO 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 at AS boundary.
3.4. Explicit Exclusion Route Subobject
As per [RFC4874], the Explicit Exclusion Route is used to specify
exclusion of certain abstract nodes between a specific pair of nodes
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or resources in the explicit route. EXRS is an ERO subobject that
contains one or more subobjects of its own, called EXRS subobjects.
The EXRS subobject could carry any of the subobjects defined for 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 ERO.
All the rules of processing are as per the [RFC4874].
4. Interaction with Path Computation Element (PCE)
The domain subobjects to be used in Path Computation Element Protocol
(PCEP) are referred to in [PCE-DOMAIN]. Note that the new domain
subobjects follow the principle that subobjects used in PCEP
[RFC5440] are identical to the subobjects used in RSVP-TE and thus
are interchangeable between PCEP and RSVP-TE.
5. IANA Considerations
5.1. New Subobjects
IANA maintains the "Resource Reservation Protocol (RSVP) Parameters"
at <http://www.iana.org/assignments/rsvp-parameters>. Within this
registry IANA maintains two sub-registries:
o EXPLICIT_ROUTE subobjects (see Sub-object type 20 EXPLICIT_ROUTE
Type 1 Explicit Route at http://www.iana.org/assignments/rsvp-
parameters)
o EXCLUDE_ROUTE subobjects (see Sub-object types of Class Types or
C-Types 232 EXCLUDE_ROUTE at http://www.iana.org/assignments/rsvp-
parameters)
Upon approval of this document, IANA is requested to make identical
additions to these registries as follows, in sync with [PCE-DOMAIN]:
Subobject Type Reference
TBD1 4-Byte AS number [This I.D.][PCE-DOMAIN]
TBD2 OSPF Area ID [This I.D.][PCE-DOMAIN]
TBD3 IS-IS Area ID [This I.D.][PCE-DOMAIN]
Further upon approval of this document, IANA is requested to add a
reference to this document to the new PCEP numbers that are
registered by [PCE-DOMAIN].
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6. Security Considerations
Security considerations for RSVP-TE and GMPLS signaling RSVP-TE
extensions are covered in [RFC3209] and [RFC3473]. This document
does not introduce any new messages or any substantive new
processing, and so those security considerations continue to apply.
Further, general considerations for securing RSVP-TE in MPLS-TE and
GMPLS networks can be found in [RFC5920]. The section 8 of [RFC5920]
describes the inter-provider security considerations, which continue
to apply.
The route exclusion security consideration are covered in [RFC4874]
and continue to apply.
7. Acknowledgments
We would like to thank Adrian Farrel, Lou Berger, George Swallow,
Chirag Shah, Reeja Paul, Sandeep Boina and Avantika for their useful
comments and suggestions.
Thanks to Vishnu Pavan Beeram for shepherding this document.
Thanks to Deborah Brungard for being the Responsible AD.
Thanks to Amanda Baber for IANA Review.
Thanks to Brian Carpenter for Gen-ART Review.
Thanks to Liang Xia (Frank) for SecDir Review.
Thanks to Spencer Dawkins and Barry Leiba for comments during the
IESG Review.
8. References
8.1. 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>.
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[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>.
[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>.
[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.
[PCE-DOMAIN]
Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
for Path Computation Element (PCE) Communication Protocol
(PCEP). (draft-ietf-pce-pcep-domain-sequence)", November
2015.
8.2. 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>.
[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>.
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[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>.
[RFC5553] Farrel, A., Ed., Bradford, R., and JP. Vasseur, "Resource
Reservation Protocol (RSVP) Extensions for Path Key
Support", RFC 5553, DOI 10.17487/RFC5553, May 2009,
<http://www.rfc-editor.org/info/rfc5553>.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<http://www.rfc-editor.org/info/rfc5920>.
[RFC6001] Papadimitriou, D., Vigoureux, M., Shiomoto, K., Brungard,
D., and JL. Le Roux, "Generalized MPLS (GMPLS) Protocol
Extensions for Multi-Layer and Multi-Region Networks (MLN/
MRN)", RFC 6001, DOI 10.17487/RFC6001, October 2010,
<http://www.rfc-editor.org/info/rfc6001>.
[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>.
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Appendix A. Examples
These examples are for illustration purposes only, to show how the
new subobjects could be encoded. They are not meant to be an
exhaustive list of all possible usecases and combinations.
A.1. Inter-Area LSP Path Setup
In an inter-area LSP path setup where the ingress and the egress
belong to different IGP areas within the same AS, the domain
subobjects could be represented using an ordered list of IGP area
subobjects in an ERO.
D2 Area D
|
|
D1
|
|
********BD1******
* | *
* | * Area C
Area A * | *
* | *
Ingress------A1-----ABF1------B1------BC1------C1------Egress
/ * | *
/ * | *
/ * Area | B *
F1 * | *
/ ********BE1******
/ |
/ |
F2 E1
|
Area F |
E2 Area E
* All IGP Area in one AS (AS 100)
Figure 1: Domain Corresponding to IGP Area
As per Figure 1, the signaling at Ingress could be -
ERO:(A1, ABF1, Area B, Area C, Egress)
It should be noted that there are other ways to achieve the desired
signaling, the area subobject provides another tool in the toolkit
and can have operational benefits when -
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o Use of PCEP like domain-sequence [PCE-DOMAIN] configurations in
explicit path such that area subobjects can be used to signal the
loose path.
o Alignment of subobjects and registries between PCEP and RSVP-TE,
thus allowing easier interworking between path computation and
signaling i.e. to and fro of subobjects between signalling and
path computation (if need be).
A.2. Inter-AS LSP Path Setup
A.2.1. Example 1
In an inter-AS LSP path setup where the ingress and the egress belong
to different AS, the domain subobjects (AS) could be used in an ERO.
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: Domain Corresponding to AS
As per Figure 2, the signaling at Ingress could be -
ERO:(A1, A2, AS B, AS C, Egress); or
ERO:(A1, A2, AS B, Area 0, AS C, Area 0, Egress).
Each AS has a single IGP area (area 0), Area subobject is optional.
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Note that to get a domain disjoint path, the ingress could also
signal the backup path with -
XRO:(AS B)
A.2.2. Example 2
As shown in Figure 3, where AS 200 is made up of multiple areas, the
signaling can include both AS and Area subobject to uniquely identify
a domain.
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Ingress *
| *
| *
| *
X1 *
\\ *
\ \ *
\ \* Inter-AS
AS 100 \* \ Link
* \ \
* \ \
* \ \
\ \ D2 Area D
AS 200 \ \ |
\ \ |
Inter \ \ D1
-AS \ \ |
Link \ \|
\ ********BD1******
\ * | *
\ * | * Area C
Area A \ * | *
\* | *
A2------A1------AB1------B1------BC1------C1------Egress
* | *
* | *
* | *
* Area | B *
********BE1******
|
|
E1
|
|
E2 Area E
Figure 3: Domain Corresponding to AS and Area
As per Figure 3, the signaling at Ingress could be -
ERO:(X1, AS 200, Area B, Area C, Egress).
Authors' Addresses
Dhody, et al. Expires May 22, 2016 [Page 17]
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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
Venugopal Reddy Kondreddy
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560037
India
EMail: venugopalreddyk@huawei.com
Ramon Casellas
CTTC
Av. Carl Friedrich Gauss n7
Castelldefels, Barcelona 08860
Spain
EMail: ramon.casellas@cttc.es
Dhody, et al. Expires May 22, 2016 [Page 18]
