LSP Attribute in ERO
draft-ietf-ccamp-lsp-attribute-ro-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Cyril Margaria , Giovanni Martinelli , Steve Balls , Ben Wright | ||
| Last updated | 2013-02-12 | ||
| Replaces | draft-margaria-ccamp-lsp-attribute-ero | ||
| Replaced by | draft-ietf-teas-lsp-attribute-ro, RFC 7570 | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | I-D Exists | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-ccamp-lsp-attribute-ro-00
CCAMP C. Margaria, Ed.
Internet-Draft Nokia Siemens Networks
Intended status: Standards Track G. Martinelli
Expires: August 11, 2013 Cisco
S. Balls
B. Wright
Metaswitch
February 07, 2013
LSP Attribute in ERO
draft-ietf-ccamp-lsp-attribute-ro-00
Abstract
LSP attributes can be specified or recorded for whole path, but they
cannot be targeted to a specific hop. This document proposes
alternative ways to extend the semantic for RSVP ERO object to target
LSP attributes to a specific hop.
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 August 11, 2013.
Copyright Notice
Copyright (c) 2013 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
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publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Contributing Authors . . . . . . . . . . . . . . . . . . . 3
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. Non solution . . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Extended ERO Object . . . . . . . . . . . . . . . . . . . 5
3.2.1. Semantic of the Extended ERO object . . . . . . . . . 5
3.2.2. Procedures . . . . . . . . . . . . . . . . . . . . . . 5
3.2.3. Subobjects . . . . . . . . . . . . . . . . . . . . . . 6
3.2.4. Processing . . . . . . . . . . . . . . . . . . . . . . 9
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References . . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
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1. Introduction
Generalized MPLS (GMPLS) Traffic Engineering (TE) Label Switched
Paths (LSPs) can be route-constrained by making use of the Explicit
Route (ERO) object and related sub-objects as defined in [RFC3209],
[RFC3473], [RFC3477], [RFC4873], [RFC4874], [RFC5520] and [RFC5553].
This document proposes mechanisms to target LSP attributes at a
specific hop. This document presents several solutions for
discussion, final document will contains only one document after WG
consensus.
1.1. Contributing Authors
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 RFC 2119 [RFC2119].
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2. Requirements
The requirement is to provide a generic mechanism to carry
information related to specific nodes when signaling an LSP. This
document does not restrict what that information can be used for.
LSP attribute defined [RFC5420] should be expressed in ERO and SERO
objects.
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3. Solutions
3.1. Non solution
A solution using a specific ERO or SERO subobject is not used because
the subobject length is limited to 8 bit, versus 16 bit for LSP
ATTRIBUTES. This does not allow to put LSP ATTRIBUTE subobjects in
ERO subobjects.
3.2. Extended ERO Object
The logic of the EXTENDED_EXPLICIT_ROUTE follows the one of SERO.The
class of the EXTENDED_EXPLICIT_ROUTE object is xxx (of the form
11bbbbbb). The EXTENDED_EXPLICIT_ROUTE object has the following
format: Class = xxx, C_Type = 1 The EXTENDED_EXPLICIT_ROUTE object
may be used if some node along the explicit route support this
object. The EXTENDED_EXPLICIT_ROUTE object is assigned a class value
of the form 11bbbbbb, so it is forwarded by nodes not supporting it.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// (Subobjects) //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Subobjects The contents of an EXTENDED_EXPLICIT_ROUTE object are a
series of variable- length data items called subobjects. The
subobjects are defined in section Section 3.2.3 below.
3.2.1. Semantic of the Extended ERO object
Extended ERO object is carried in Path messages and carries a list of
hops extended with hop-specific information. It is structured as a
sequence of hop identifier subobjects (to indicate the hop who should
process the subsequent attributes) and a series of hop attributes
(which may be mandatory or optional) for the specified hop to
process.
3.2.2. Procedures
If a Path message contains multiple EXTENDED_EXPLICIT_ROUTE objects,
only the first object is meaningful. Subsequent
EXTENDED_EXPLICIT_ROUTE objects MAY be ignored and SHOULD NOT be
propagated. An EXTENDED_EXPLICIT_ROUTE SHOULD contain at least 2
subobjects. The first subobject MUST indicate a node or link that
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identifies a hop that should process the next subobject(s). The
address used to identify the hop SHOULD also be listed in the ERO or
an SERO. This ensures that the extended attribute is for a node or
link along the LSP path. The second subobject SHOULD contains an
extended node or link information. In this document this SHOULD be a
LSP Attribute subobject.
3.2.3. Subobjects
The content of an EXTENDED_EXPLICIT_ROUTE are a series of variable
length subobjects. Each subobject has the following form
0 1 2
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//-----------+
| Type | Length | (Subobject contents)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--------//-----------+
The Type indicates the type of contents of the subobject. Currently
defined values are:
1 Hop identifier subobject containing an ERO subobject:
IPv4 prefix
IPv6 prefix
Unnumbered Interface ID
Autonomous system number
Path Key with 32-bit PCE ID
Path Key with 128-bit PCE ID
Per-hop attributes:
XX LSP Attribute
Length The Length contains the total length of the subobject in
bytes, including the Type and Length . The Length MUST be at least
4, and MUST be a multiple of 4.
3.2.3.1. Hop identifier
The Hop identifier subobject contains exactly one ERO subobject
identifying a hop. The value of the subobject is a copy of the ERO
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subobject definition. The format of the subobject is as follow:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |L| sub Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub Length | (Subobject contents) ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 0x01 Hop Identifier
Length The Length contains the total length of the subobject in
bytes, including the Type and Length fields.
Sub type The ERO subobject type, the same as the ERO subobject type.
the ERO type defined are :
1 IPv4 prefix
2 IPv6 prefix
3 Reserved
4 Unnumbered Interface ID
32 Autonomous system number
33 Reserved
37 Reserved
64 Path Key with 32-bit PCE ID
65 Path Key with 128-bit PCE ID
Sub length The ERO subobject type, the same as the ERO subobject
length. It its unchanged compared to the ERO subobject
definition.
Subobject contents The ERO subobject content, it its unchanged
compared to the ERO subobject definition.
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3.2.3.2. Hop LSP Attribute
The LSP attribute subobject contains information targeted at the hop
identified by the preceding hop identifier subobject.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | Reserved |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The attributes TLV are encoded as defined in [RFC5420] section 3.
Type x TBD by IANA.
Length The Length contains the total length of the subobject in
bytes, including the Type and Length fields. The Length MUST be
always divisible by 4.
Reserved Reserved, must be set to 0 when the subobject is inserted
in the ERO, MUST NOT be changed when a node process the ERO and
must be ignored on the node addressed by the preceding ERO
subobjects
R This bit reflects the LSP_REQUIRED_ATTRIBUTE and LSP_ATTRIBUTE
semantic. When set indicates required LSP attributes to be
processed by the node, when cleared the LSP attributes are not
required as described in Section 3.2.3.3.
3.2.3.3. Processing
Following [RFC3209] and [RFC3473] the Extended ERO is managed as a
list where each hop information starts with a subobject identifying
an abstract node or link. The LSP attribute subobject must be
appended after the hop identifier subobject (which follows the
formatting of the objects defined in [RFC3209], [RFC3473], [RFC3477],
[RFC4873], [RFC4874], [RFC5520] and [RFC5553]. Several LSP attribute
subobject MAY be present for each hop identification object.
When the R bit is set a node MUST examine the attribute TLV present
in the subobject following the rules described in [RFC5420] section
5.2. When the R bit is not set a node MUST examine the attribute TLV
present in the subobject following the rules described in [RFC5420]
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section 4.2. If more than one ERO LSP attribute subobject having the
R bit set is present, the first one MUST be processed and the others
SHOULD be ignored. If more than one ERO LSP attribute subject having
the R bit cleared is present for the same hop identification object,
then the first one MUST be processed and the others SHOULD be
ignored.
3.2.4. Processing
A node receiving a Path message containing an EXTENDED_EXPLICIT_ROUTE
object must determine if the extended hop information is applicable
for this node. The node performs the following steps:
1. The node receiving the RSVP message MUST first evaluate if the
ERO object is present. If the ERO object is not present it has
received the message in error and SHOULD return a pathError
message.
2. Second the node MUST read the first subobject. If the node is
not part of the abstract node described by the first subobject,
the processing stops.
3. If there is no second subobject this indicates the end of the
extended ERO. The extended ERO SHOULD be removed from the Path
message. A new extended ERO MAY be added to the Path message.
4. Next the node evaluates the second subobject.
A. If the subobject identified an abstract node and the node is
also part of the abstract node, then the node deletes the
first subobject and continue processing with step 3.
B. If the subobject identified an abstract node and the node is
not part of the abstract node, then the extended ERO is
invalid and the node SHOULD return a PathErr with error code
"Routing Error" and error value "Bad EXTENDED_EXPLICIT_ROUTE
object" with the EXTENDED_EXPLICIT_ROUTE object included,
truncated (on the left) to the offending unrecognized
subobject
C. If the subobject is an LSP Attribute subobject it processes
it according to the rules for that subobject and removes it
from the extended ERO. If the extended ERO does not contain
further subject it SHOULD be removed from the Path message.
A new extended ERO MAY be added to the Path message.
If a node finds a hop identification object which matches the local
router handling of the subobject it will behave as described in
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[RFC3209] when an unrecognized ERO subobject is encountered. This
node will return a PathErr with error code "Routing Error" and error
value "Bad EXTENDED_EXPLICIT_ROUTE object" with the
EXTENDED_EXPLICIT_ROUTE object included, truncated (on the left) to
the offending unrecognized subobject.
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4. IANA Considerations
TBD once a final approach has been chosen.
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5. Security Considerations
None.
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6. Acknowledgments
The authors would like to thanks Lou Berger for his directions and
Attila Takacs for inspiring this
[I-D.kern-ccamp-rsvpte-hop-attributes]. The authors also thanks Dirk
Schroetter for his contribution to the initial versions of the
documents (version -00 up to -02).
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7. References
7.1. 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.
[RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
in Resource ReSerVation Protocol - Traffic Engineering
(RSVP-TE)", RFC 3477, January 2003.
[RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., and A. Farrel,
"GMPLS Segment Recovery", RFC 4873, May 2007.
[RFC4874] Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
Extension to Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE)", RFC 4874, April 2007.
[RFC5420] Farrel, A., Papadimitriou, D., Vasseur, JP., and A.
Ayyangarps, "Encoding of Attributes for MPLS LSP
Establishment Using Resource Reservation Protocol Traffic
Engineering (RSVP-TE)", RFC 5420, February 2009.
[RFC5520] Bradford, R., Vasseur, JP., and A. Farrel, "Preserving
Topology Confidentiality in Inter-Domain Path Computation
Using a Path-Key-Based Mechanism", RFC 5520, April 2009.
[RFC5553] Farrel, A., Bradford, R., and JP. Vasseur, "Resource
Reservation Protocol (RSVP) Extensions for Path Key
Support", RFC 5553, May 2009.
7.2. Informative References
[I-D.kern-ccamp-rsvpte-hop-attributes]
Kern, A. and A. Takacs, "Encoding of Attributes of LSP
intermediate hops using RSVP-TE",
draft-kern-ccamp-rsvpte-hop-attributes-00 (work in
progress), October 2009.
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Authors' Addresses
Cyril Margaria (editor)
Nokia Siemens Networks
St Martin Strasse 76
Munich, 81541
Germany
Phone: +49 89 5159 16934
Email: cyril.margaria@nsn.com
Giovanni Martinelli
Cisco
via Philips 12
Monza 20900
IT
Phone: +39 039 209 2044
Email: giomarti@cisco.com
Steve Balls
Metaswitch
100 Church Street
Enfield EN2 6BQ
UJ
Phone: +44 208 366 1177
Email: steve.balls@metaswitch.com
Ben Wright
Metaswitch
100 Church Street
Enfield EN2 6BQ
UJ
Phone: +44 208 366 1177
Email: Ben.Wright@metaswitch.com
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