Include Routes - Extension to Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)
draft-ali-ccamp-rsvp-te-include-route-03
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| Authors | Zafar Ali , George Swallow , Clarence Filsfils , Ori Gerstel , Kenji Kumaki , Ruediger Kunze | ||
| Last updated | 2013-02-25 | ||
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draft-ali-ccamp-rsvp-te-include-route-03
CCAMP Working Group Zafar Ali
Internet Draft George Swallow
Intended status: Standard Track Clarence Filsfils
Expires: August 24, 2013 Ori Gerstel
Cisco Systems
Kenji Kumaki
KDDI Corporation
Ruediger Kunze
Deutsche Telekom AG
February 25, 2013
Include Routes - Extension to
Resource ReserVation Protocol-Traffic Engineering (RSVP-TE)
draft-ali-ccamp-rsvp-te-include-route-03.txt
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Abstract
There are scenarios that require two or more LSPs or segments of
LSPs to 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).............4
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
There are scenarios that require two or more LSPs to follow same
route in the network. E.g., many deployments require 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: an application may require 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.
. 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.
Similarly, there are scenarios where two or more LSPs need to
follow a given resource in the network, e.g., two partially
overlapping Label Switched Paths (LSPs) are required. In this
case, inclusion of certain abstract nodes or resources between a
specific pair of abstract nodes present in an ERO is required.
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. Included (but not limited to) are 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
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loose hop into a proper sequence of strict or a sequence of
finer-grained loose hops.
. The ingress node requires two Label Switched Paths (LSPs) to
follow the same route but has no knowledge of how a loose hop
of a reference LSP was expanded.
When the entire route of the LSPs that need to follow the same
path is computed by the ingress node, the aforementioned
requirements can be met by a local decision at the ingress node.
However, there are scenarios where a full route computation is
not performed at the ingress but instead is performed by remote
nodes. This case creates 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 these requirements and defines
procedures that may be used to signal LSPs such that the entire
LSP or LSP segments 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.
2.1. Explicit Inclusion Route Subobject (EIRS)
The Explicit Inclusion Route Subobject (EIRS) defines abstract
nodes or resources (such as IPv4 address, IPv6 address, Circuit
IDs (see [DRAFT-LSP-XRO]), unnumbered interfaces, 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.
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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 IPv4 inclusion (IPv4 addr 1 and IPv4
addr 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 | IPv4 Addr1 (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Addr1 (continued) |Prefix Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|L| Type | Length | IPv4 Addr2 (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Addr2 (continued) | Prefix Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Example of EIRS with IPv4 prefix subobjects
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 IPv4 Addr2 value).
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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 the following subobjects:
EIRS.SubobjectN.Type = 1: IPv4 address [RFC3209]. This
object is typically used when a specific TE link or node
identified by the specified IPv4 address is to be
included.
EIRS.SubobjectN.Type = 2: IPv6 address [RFC3209]. This
object is typically used when a specific TE link or node
identified by the specified IPv6 address is to be
included.
EIRS.SubobjectN.Type = 4: Unnumbered Interface ID
[RFC3477]. This object is typically used when a specific
unnumbered TE link with specified IPv4 node address and
interface identified is to be included.
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EIRS.SubobjectN.Type = 32: Autonomous system number
[RFC3209]. This object is typically used when a specific
Autonomous system is to be included.
EIRS.SubobjectN.Type = 35: Switching Capability (SC)
[RFC6001]. This object is typically used when a specific
Switching Capability is to be included.
EIRS.SubobjectN.Type = TBD (suggested value 37): LSP
subobject [DRAFT-LSP-XRO-SUB]. This object is typically
used when two or more LSPs need to follow same route in
the network (for example for fate sharing).
Please note that EIRS.SubobjectN.Type = 3: Label
[RFC6001], EIRS.SubobjectN.Type = 33: Explicit Exclusion
Route subobject (EXRS) [RFC4874] and EIRS.SubobjectN.Type
= 34: SRLG [RFC4874] are not supported.
This document does not preclude a route inclusion from listing
arbitrary nodes or network elements to include. However, the
intent is to indicate only the minimal number of subobjects to
be explicitly avoided. For instance, when the requirement is to
have two or more LSPs need to follow the same route in the
network, it may be necessary to signal only the LSP subobject.
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 Path Diversity using Exclude Routes'',
draft-ietf-ccamp-lsp-diversity, 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
Kenji Kumaki
KDDI Corporation
Email: ke-kumaki@kddi.com
Rudiger Kunze
Deutsche Telekom AG
Ruediger.Kunze@telekom.de
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