CCAMP C. Margaria, Ed.
Internet-Draft Coriant GmbH
Intended status: Standards Track G. Martinelli
Expires: January 16, 2014 Cisco
S. Balls
B. Wright
Metaswitch
July 15, 2013
LSP Attribute in ERO
draft-ietf-ccamp-lsp-attribute-ro-02
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
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Contributing Authors . . . . . . . . . . . . . . . . . . 2
1.2. Requirements Language . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 3
3. ERO Attribute . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. ERO_ATTRIBUTE subobject . . . . . . . . . . . . . . . . . 3
3.2. HOP Attributes TLVs . . . . . . . . . . . . . . . . . . . 4
3.3. Procedures . . . . . . . . . . . . . . . . . . . . . . . 5
4. Recording Hop attribute per LSP . . . . . . . . . . . . . . . 5
4.1. RRO Hop Attributes subobject . . . . . . . . . . . . . . 5
4.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . 6
4.2.1. Subobject presence rule . . . . . . . . . . . . . . . 6
4.2.2. Reporting Compliance with ERO Hop Attributes . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
8.1. Normative References . . . . . . . . . . . . . . . . . . 7
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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].
Those route constraints are extended by a number of documents,
including element defined in [RFC6163],
[I-D.ietf-ccamp-wson-signaling],
[I-D.dong-ccamp-rsvp-te-mpls-tp-li-lb] or
[I-D.ali-ccamp-rc-objective-function-metric-bound], for example the
WSON_SIGNALING object, Metric and Objective Function subobjects.
RSVP already supports generic extension of LSP attributes in
[RFC5420]. In order to support current and future ERO constraint
extensions this document defines a mechanism to target generic
attributes at a specific hop.
1.1. Contributing Authors
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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].
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. A
mechanism similar to LSP attribute defined [RFC5420] should be
expressed in ERO and SERO objects. A new ERO sub-object is defined,
containing a list of generic Hop attributes. The mechanism defined
in this document limits itself to single HOP attributes, and does not
address attributes valid for a LSP section [[This can be revised
based on feedback]]
3. ERO Attribute
The ERO Attributes subobject may be carried in the ERO or SERO object
if they are present. The subobject uses the standard format of an
ERO subobject.
3.1. ERO_ATTRIBUTE subobject
The length is variable and content MUST be the same as for the
LSP_ATTRIBUTE object with Attributes TLVs. The size of the ERO sub-
object limits the size of the LSP Attribute TLV to 250 bytes. The
typical size of currently defined and forthcoming LSP_ATTRIBUTE TLVs
applicable to a specific hop (WSON_SIGNALING, OF and Metric) is not
foreseen to exceed this limit.
The ERO attribute subobject is defined 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 |R|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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See [RFC3209] for a description of L parameters. The attributes TLV
are encoded as defined in section Section 3.2.
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 defined in [RFC5420]. When set indicates required LSP
attributes to be processed by the node, when cleared the LSP
attributes are not required as described in Section 3.3.
Attributes TLVs as defined in Section 3.2 .
3.2. HOP Attributes TLVs
ERO Attributes carried by the new objects defined in this document
are encoded within TLVs. One or more TLVs may be present in each
object. There are no ordering rules for TLVs, and no interpretation
should be placed on the order in which TLVs are received.
Each TLV 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Value //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type The identifier of the TLV..
Length Indicates the total length of the TLV in octets. That is,
the combined length of the Type, Length, and Value fields, i.e.,
four plus the length of the Value field in octets. The entire TLV
MUST be padded with between zero and three trailing zeros to make
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it four-octet aligned. The Length field does not count any
padding.
Value The data carried in the TLV.
3.3. Procedures
As described in [RFC3209] and [RFC3473] the ERO is managed as a list
where each hop information starts with a subobject identifying an
abstract node or link. The ERO attribute subobject must be appended
after the existing subobjects defined in [RFC3209], [RFC3473],
[RFC3477], [RFC4873], [RFC4874], [RFC5520] and [RFC5553]. Several
ERO attribute subobject MAY be present, for each hop.
If a node is processing an ERO attribute subobject and does not
support handling of the subobject it will behave as described in
[RFC3209] when an unrecognized ERO subobject is encountered. 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 unrecognized
subobject.
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]
section 4.2.
A node processing an ERO attribute subobject with an HOP attribute
TLV longer than the ERO subobject 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
offending malformed subobject. The processing of the Hop attribute
TLVs should be described in the documents defining them.
4. Recording Hop attribute per LSP
In some cases it is important to determine if an optional Hop
attribute has been processed by a node.
4.1. RRO Hop Attributes subobject
The RRO Hop Attributes subobject may be carried in the RECORD_ROUTE
object if it is present. The subobject uses the standard format of
an RRO subobject.
The RRO Hop attribute subobject is defined as follows:
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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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// Attributes TLVs //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
See [RFC3209] for a description of L parameters. The attributes TLV
are encoded as defined in section Section 3.2.
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 RRO, MUST NOT be changed when a node process the RRO and
must be ignored on the node addressed by the preceding RRO
subobjects.
Attributes TLVs The processed or addition HOP attributes, using the
format defined in Section 3.2 .
4.2. Procedures
4.2.1. Subobject presence rule
The RRO rules defined in [RFC3209] are not changed. The RRO Hop
attribute subobject must be pushed after the RRO attribute subobject
(if present) defined in in [RFC5420]. The RRO Hop attribute
subobject MAX be present between a pait of subobject identifying LSR
or links. All such subobjects MUST be forwarded unmodified by
transit LSRs.
4.2.2. Reporting Compliance with ERO Hop Attributes
To report that an ERO Hop attribute has been considered, or to report
an additional attribute, an LSR MAY add a RRO Hop Attributes
subobject with the HOP Attribute used. The requirement to report
compliance MUST be specified in the document that defines the usage
of an Hop attribute. [[This is not the most efficient encoding, a
more efficient encoding would use a bit field ala RFC5420 ]]
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5. IANA Considerations
TBD once a final approach has been chosen.
6. Security Considerations
None.
7. 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).
8. References
8.1. 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.
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[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.
8.2. Informative References
[I-D.ali-ccamp-rc-objective-function-metric-bound]
Ali, Z., Swallow, G., Filsfils, C., Fang, L., Kumaki, K.,
and R. Kunze, "Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) extension for signaling Objective
Function and Metric Bound", draft-ali-ccamp-rc-objective-
function-metric-bound-02 (work in progress), July 2012.
[I-D.dong-ccamp-rsvp-te-mpls-tp-li-lb]
Dong, J., Chen, M., and Z. Li, "GMPLS RSVP-TE Extensions
for Lock Instruct and Loopback", draft-dong-ccamp-rsvp-te-
mpls-tp-li-lb-05 (work in progress), December 2012.
[I-D.ietf-ccamp-wson-signaling]
Bernstein, G., Xu, S., Lee, Y., Martinelli, G., and H.
Harai, "Signaling Extensions for Wavelength Switched
Optical Networks", draft-ietf-ccamp-wson-signaling-06
(work in progress), July 2013.
[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.
[RFC6163] Lee, Y., Bernstein, G., and W. Imajuku, "Framework for
GMPLS and Path Computation Element (PCE) Control of
Wavelength Switched Optical Networks (WSONs)", RFC 6163,
April 2011.
Authors' Addresses
Cyril Margaria (editor)
Coriant GmbH
St Martin Strasse 76
Munich 81541
Germany
Phone: +49 89 5159 16934
Email: cyril.margaria@coriant.com
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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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