CCAMP Working Group Zafar Ali
Internet Draft George Swallow
Intended status: Standard Track Clarence Filsfils
Expires: September 11, 2012 Ori Gerstel
Cisco Systems
Ruediger Kunze
Deutsche Telekom AG
March 12, 2012
Include Routes - Extension to
Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)
draft-ali-ccamp-rsvp-te-include-route-01.txt
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Abstract
There are scenarios in which it is required that two or more LSPs
or segments of LSPs follow same route in the network. This document
specifies methods to communicate route inclusions along the loose
hops during path setup using the Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE) protocol.
Conventions used in this document
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 RFC 2119
[RFC2119].
Table of Contents
Copyright Notice..................................................1
1. Introduction...................................................3
2. RSVP-TE signaling extensions...................................4
2.1. Explicit Inclusion Route Subobject (EIRS)..............5
2.2. EIRS Subobject Processing Rule.........................7
2.3. Processing of EIRS with XRO and EXRS...................9
3. Security Considerations........................................9
4. IANA Considerations............................................9
5. Acknowledgments................................................9
6. References....................................................10
6.1. Normative References..................................10
6.2. Informative References................................11
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1. Introduction
The RSVP-TE specification, "RSVP-TE: Extensions to RSVP for LSP
Tunnels" [RFC3209] and GMPLS extensions to RSVP-TE, "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Resource
ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions"
[RFC3473] allow abstract nodes and resources to be explicitly
included in a path setup. However, such inclusion may not be
possible when a loose hop is expanded. It is obviously possible
to divide the loose hop into multiple loose hops and construct
an inclusion in that fashion. However, there are scenarios where
division of a loose hop into multiple explicit loose hops is not
possible, including but not limited to the following:
. When the destination is in another area, AS, or across a UNI,
the ingress node may not have full visibility of the topology.
In cases where the ingress node lacks sufficient topological
knowledge around the loose hop, it is not able to divide a
loose hop into a proper sequence of strict or a sequence of
finer-grained loose hops.
. The ingress node requires that two Label Switched Paths
(LSPs) follow the same route but has no knowledge of how a
loose hop of a reference LSP was expanded. There are scenarios
in which it is required that two or more LSPs follows same
route in the network. E.g., in many deployments it is required
that member LSPs of a bundle/ aggregated link (or Forwarding
Adjacency (FA))) follow the same route. Possible reasons for
two or more LSPs to follow the same end-to-end or partial
route include, but are not limited to:
- Fate sharing: it is sometimes required that two or more
LSP fail together. In the example of bundle link this would
mean that if one component goes down, the entire bundle
goes down.
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- Homogeneous Attributes: it is often required that two or
more LSPs have the same TE metrics like latency, delay
variation, etc. In the example of a bundle/ aggregated link
this would meet the requirement that all component links
(FAs) of a bundle should have same latency and delay
variation. As noted in [OSPF-TE-METRIC] and [ISIS-TE-
METRIC], in certain networks, such as financial information
networks, network performance (e.g. latency and latency
variation) is becoming critical and hence having bundles
with component links (FAs) with homogeneous delay and delay
variation is important.
. The ingress node requires certain SLRGs to be explicitly
"included" when the loose hop is expanded. This document
defines inclusion use of the SRLG subobject defined in
[RFC4874].
When the entire route of LSPs that need to follow the same route
is computed by the ingress node, the aforementioned requirements
can be met by a local decision at the ingress node. However,
there are scenarios when a route computation is not performed at
the ingress and instead are performed by remote nodes, in which
case there is a need for relevant affinity requirements to be
communicated to the route expanding nodes. These include (but are
not limited to):
. LSPs with loose hops in the Explicit Route Object (ERO), e.g.
inter-domain LSPs.
. Generalized Multi-Protocol Label Switching (GMPLS) User-
Network Interface (UNI) where route computation may be
performed by the UNI-Network (server) node;
This document addresses the above-mentioned requirements/
scenarios and defines procedures that may be used to signal LSPs
such that the entire LSP or segments of LSP follow the same
route.
2. RSVP-TE signaling extensions
A new ERO subobject type the Explicit Inclusion Route Subobject
(EIRS) is introduced to indicate an inclusion between a pair of
included nodes or abstract nodes. The ERO subobject encoding and
processing rules are similar to Explicit Exclusion Route
Subobject (EXRS) subobject of ERO defined in [RFC4874], with the
exception of include vs. exclude usage.
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2.1. Explicit Inclusion Route Subobject (EIRS)
The Explicit Inclusion Route Subobject (EIRS) defines abstract
nodes or resources (such as links, SRLG, Circuit IDs (see
[DRAFT-LSP-XRO]), unnumbered interfaces, or labels, etc.) that
must or should be used on the path between two inclusive
abstract nodes or resources in the explicit route. An EIRS is an
ERO subobject that contains one or more subobjects of its own,
called EIRS subobjects. Each EIRS may carry multiple inclusions.
The inclusion is encoded exactly as for XRO subobjects and
prefixed by an additional Type and Length.
The format of the EIRS is 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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// one or more EIRS subobjects //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
An example of EIRS for SLRG inclusion (SRLG Id 1 and SRLG Id
2) is provided in the following. This example is referenced in
the following description.
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | SRLG Id 1 (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG Id 1 (continued) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | SRLG Id 2(4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SRLG Id 2 (continued) | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Example of EIRS with SRLG subobjects
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Please note that there are two or more "L bits" in an EIRS. The
following convention is used to reference the individual "L
bits".
EIRS.L: The L bit of the header of the EIRS subobject.
E.g., EIRS.L refers to the first L bit in EIRS example in
Figure 1.
EIRS.SubobjectN.L: The L bit of the nth subobject of EIRS.
E.g., EIRS.Subobject2.L refers to the third L bit in EIRS
example in Figure 1 (i.e., the L bit to define the
expected treatment of SRLG ID2 value).
The fields of the EIRS subobject are defined as follows:
EIRS.L bit: The L bit is an attribute of the EIRS
subobject. The L bit SHOULD be set, so that the subobject
represents a loose hop in the explicit route.
EIRS.Type: The type of the subobject is to be defined by
IANA (Suggested Value: 68).
EIRS.Reserved: This field is reserved. It SHOULD be set to
zero on transmission and MUST be ignored on receipt.
EIRS subobjects: An EIRS subobject indicates the abstract
node or resource to be included in the path. The format of
an EIRS subobject is exactly the same as the format of a
subobject in the eXclude Route Object (XRO) (See [RFC4874]
and [DRAFT-LSP-XRO-SUB]). This is with the exception of
the interpretation of the "EIRS.SubobjectN.L bit" of the
subobjects, as detailed in the following.
EIRS.SubobjectN.L bit: For all supported subobjects of
EIRS, the EIRS.SubobjectN.L bit has the following
interpretation.
- EIRS.SubobjectN.L = 0 indicates that the attribute
specified MUST be included.
- EIRS.SubobjectN.L = 1 indicates that the attribute
specified SHOULD be included.
An EIRS may include all subobjects defined in this
document for the XRO (See [RFC4874] and [DRAFT-LSP-XRO-
SUB]). Specifically, an EIRS may include the following
subobjects:
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EIRS.SubobjectN.Type = 1: IPv4 address [RFC3209].
EIRS.SubobjectN.Type = 2: IPv6 address [RFC3209].
EIRS.SubobjectN.Type = 3: Label [RFC6001].
EIRS.SubobjectN.Type = 4: Unnumbered Interface ID
[RFC3477].
EIRS.SubobjectN.Type = 32: Autonomous system number
[RFC3209].
EIRS.SubobjectN.Type = 34: SRLG [RFC4874].
EIRS.SubobjectN.Type = 35: Switching Capability (SC)
[RFC6001].
EIRS.SubobjectN.Type = TBD (suggested value 37): LSP
[DRAFT-LSP-XRO-SUB].
Please note that EIRS.SubobjectN.Type = 33: Explicit
Exclusion Route subobject (EXRS) [RFC4874] is not
supported.
2.2. EIRS Subobject Processing Rule
The scope of the inclusion is the previous ERO subobject that
identifies a node or an abstract node, and the subsequent ERO
subobject that identifies a node or an abstract node. The
processing rules of the EIRS are the same as the processing rule
of the EXRS, with the exception that EIRS subobjects request
resource inclusion, whereas EXRS subobjects request resource
exclusion.
Multiple inclusions may be present between any pair of nodes or
abstract nodes. An EIRS may be present when an EXRS is also
present in the ERO and/ or an XRO is also present in the path
message. Section 2.3 discusses details of processing of the EIRS
with the XRO object and the EXRS subobject of ERO.
If the processing node does not understand the EIRS subobject,
it behaves 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 EIRS subobject.
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If the EIRS.L bit is not set, the processing node SHOULD
generate a Path Error with error code "Routing Problem" and
error subcode "Bad EXPLICIT_ROUTE object".
If the processing node understands the EIRS subobject and all
the subobjects contained in the EIRS, it takes the following
steps:
. For all subobjects contained in the EIRS such that
EIRS.SubobjectN.L = 0, the processing node finds a path that
MUST include the resource attribute identified by the
EIRS.SubobjectN.
. For all subobjects contained in the EIRS such that
EIRS.SubobjectN.L = 1, the processing node finds a path that
MUST include the resource attribute identified by the
EIRS.SubobjectN.
. If the processing node fails to find a route such that the
all resources identified in the EIRS.SubobjectN for all N can
be included in the route (depending on EIRS.SubobjectN.L bit
setting), the node SHOULD return a PathErr with the error code
"Routing Problem" and error value "Route Blocked by Include
Route". The error subcode "Route Blocked by Include Route" for
Path Error code "Routing Problem" is to be assigned by IANA
(Suggested Value: 110).
If the processing node understands the EIRS subobject but does
not understand or support a subobject contained in the EIRS (say
EIRS. SubobjectN), it SHOULD 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 EIRS subobject containing the unsupported EIRS.subobjectN.
A node MAY reject a Path message if the EIRS is too large or
complicated for the local implementation or as governed by local
policy. In this case, the node SHOULD send a PathErr message
with the error code "Routing Error" and error subcode "EIRS Too
Complex". An ingress node receiving this error code/subcode
combination MAY reduce the complexity of the EIRS. The error
subcode "EIRS Too Complex" for Path Error code "Routing Problem"
is to be assigned by IANA (Suggested Value: 111).
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2.3. Processing of EIRS with XRO and EXRS
A node performing ERO expansion MAY find an XRO in the Path
message and both EIRS and EXRS subobjects in ERO. In this case,
the processing node MUST include all resources identified in the
EIRS and exclude all resources identified in the EXRS and XRO.
If the constraints identified by the EIRS, EXRS and XRO conflict
each other, the processing node SHOULD send a PathErr message
with the error code "Routing Error" and error subcode
"inconsistent include/ exclude constraints". The error subcode
"inconsistent include/ exclude constraints" for Path Error code
"Routing Problem" is to be assigned by IANA (Suggested Value:
112).
3. Security Considerations
This document does not introduce any additional security issues
above those identified in [RFC5920], [RFC2205], [RFC3209], and
[RFC3473] and [RFC4874].
4. IANA Considerations
This document adds the following new subobject of the existing
entry for ERO (20, EXPLICIT_ROUTE):
Value Description
----- ------------
TBA (suggest value: 68) Explicit Inclusion Route Subobject
(EIRS)
These subobject may be present in the Explicit Route Object, but
not in the Route Record Object.
5. Acknowledgments
Authors would like to thank Matt Hartley, Gabriele Maria
Galimberti, Luyuan Fang and Walid Wakim for their review
comments.
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6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan,
V., and G. Swallow, "RSVP-TE: Extensions to RSVP for
LSP Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[RFC 3473] Berger, L., Ed., "Generalized Multi-Protocol Label
Switching (GMPLS) Signaling Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Extensions",
RFC 3473, January 2003.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude
Routes - Extension to Resource ReserVation Protocol-
Traffic Engineering (RSVP-TE)", RFC 4874, April 2007.
[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, October 2010.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered
Links in Resource ReSerVation Protocol - Traffic
Engineering (RSVP-TE)", RFC 3477, January 2003.
[DRAFT-LSP-XRO-SUB] Ali, Z., Swallow, G., Filsfils, C., et al,
"Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) LSP
Route Diversity using Exclude Routes", draft-ali-ccamp-
xro-lsp-subobject, work in progress.
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6.2. Informative References
[RFC4208] Swallow, G., Drake, J., Ishimatsu, H., and Y. Rekhter,
"Generalized Multiprotocol Label Switching (GMPLS)
User-Network Interface (UNI): Resource ReserVation
Protocol-Traffic Engineering (RSVP-TE) Support for the
Overlay Model", RFC 4208, October 2005.
[RFC2209] Braden, R. and L. Zhang, "Resource ReSerVation
Protocol (RSVP) -- Version 1 Message Processing
Rules", RFC 2209, September 1997.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, July 2010.
Authors' Addresses
Zafar Ali
Cisco Systems, Inc.
Email: zali@cisco.com
George Swallow
Cisco Systems, Inc.
swallow@cisco.com
Clarence Filsfils
Cisco Systems, Inc.
cfilsfil@cisco.com
Ori Gerstel
Cisco Systems
ogerstel@cisco.com
Rudiger Kunze
Deutsche Telekom AG
Ruediger.Kunze@telekom.de
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