Internet DRAFT - draft-ietf-ospf-lsa-extend
draft-ietf-ospf-lsa-extend
Network Working Group P. Psenak
Internet-Draft S. Previdi
Intended status: Standards Track C. Filsfils
Expires: February 12, 2015 Cisco Systems
H. Gredler
Juniper Networks, Inc.
R. Shakir
British Telcom
W. Henderickx
Alcatel-Lucent
J. Tantsura
Ericsson
A. Lindem
Cisco Systems
August 11, 2014
OSPFv2 LSA Extendibility
draft-ietf-ospf-lsa-extend-00.txt
Abstract
OSPFv2 requires functional extension beyond what can readily be done
with the fixed-format Link State Advertisements (LSAs) as described
in RFC 2323. This document defines OSPF opaque LSAs based on Type-
Length-Value (TLV) tuples that can be used to associate additional
attributes with advertised prefixes or links. The OSPF opaque LSAs
are optional and fully backward compatible.
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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This Internet-Draft will expire on February 12, 2015.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 4
1.2. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 4
2. OSPFv2 Extended Prefix Opaque LSA . . . . . . . . . . . . . . 4
2.1. OSPFv2 Extended Prefix TLV . . . . . . . . . . . . . . . . 6
3. OSPFv2 Extended Link Opaque LSA . . . . . . . . . . . . . . . 7
3.1. OSPFv2 Extended Link TLV . . . . . . . . . . . . . . . . . 8
4. Backward Compatibility . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
6.1. OSPF Extended Prefix LSA TLV Registry . . . . . . . . . . 10
6.2. OSPF Extended Prefix TLV Sub-TLV Registry . . . . . . . . 11
6.3. OSPF Extended Link LSA TLV Registry . . . . . . . . . . . 11
6.4. OSPF Extended Link TLV Sub-TLV Registry . . . . . . . . . 11
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.1. Normative References . . . . . . . . . . . . . . . . . . . 12
7.2. Informative References . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
OSPFv2 requires functional extension beyond what can readily be done
with the fixed-format Link State Advertisements (LSAs) as described
in RFC 2328 [OSPFV2]. This document defines OSPF opaque LSAs based
on Type-Length-Value (TLV) tuples that can be used to associate
additional attributes with advertised prefixes or links. The OSPF
opaque LSAs are optional and fully backward compatible. This is in
contrast to the approach taken in OSPFv3 [OSPFV3-LSA-EXTEND] where
the existing LSAs will be replaced TLV-based extended LSAs.
New requirements such as source/destination routing, route tagging,
and segment routing necessitate this extension.
The specfication defines the following OSPFv2 opaque LSAs:
1. OSPFv2 Extended Prefix LSA - Allows advertisement of additional
attributes for prefixes advertised in Router-LSAs, Network-LSAs,
Network-Summary-LSAs, NSSA-LSAs, and AS-External-LSAs [OSPFV2]
2. OSPFv2 Extended links LSA - Allows advertisement of additional
attributes for links advertised in Router-LSAs.
Additionally, the following TLVs are defined:
1. OSPFv2 Extended Prefix TLV - Top level TLV advertising attributes
for a prefix in the OSPFv2 Extended Prefix LSA.
2. OSPFv2 Extended Link TLV - Top level TLV advertising attributes
for a link in the OSPFv2 Extended link LSA.
1.1. Requirements notation
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-KEYWORDS].
1.2. Acknowledgments
We would like to thank Anton Smirnov for his contribution.
2. OSPFv2 Extended Prefix Opaque LSA
The OSPFv2 Extended Prefix Opaque LSA will be used to advertise
additional prefix attributes. Opaque LSAs are described in [OPAQUE].
Multiple OSPFv2 Extended Prefix Opaque LSAs can be advertised by an
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OSPFv2 router. The flooding scope of the OSPFv2 Extended Prefix
Opaque LSA depends on the scope of the advertised prefixes and is
under the control of the advertising router. In some cases (e.g.,
mapping server deployment), the LSA flooding scope may be greater
than the scope of the corresponding prefixes.
The format of the OSPFv2 Extended Prefix Opaque LSA 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS age | Options | 9, 10, or 11 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque type | Instance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS checksum | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- TLVs -+
| ... |
OSPFv2 Extended Prefix LSA
The opaque type used by OSPFv2 Extended Prefix Opaque LSA is 7.
The format of the TLVs within the body of the OSPFv2 Extended Prefix
LSA is the same as the format used by the Traffic Engineering
Extensions to OSPF [TE]. The variable TLV section consists of one or
more nested Type/Length/Value (TLV) tuples. Nested TLVs are also
referred to as sub-TLVs. The format of each TLV is:
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... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
TLV Format
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The Length field defines the length of the value portion in octets
(thus a TLV with no value portion would have a length of 0). The TLV
is padded to 4-octet alignment; padding is not included in the length
field (so a 3-octet value would have a length of 3, but the total
size of the TLV would be 8 octets). Nested TLVs are also 32-bit
aligned. For example, a 1-byte value would have the length field set
to 1, and 3 octets of padding would be added to the end of the value
portion of the TLV.
2.1. OSPFv2 Extended Prefix TLV
The OSPF Extended Prefix TLV is used in order to advertise additional
attributes associated with the prefix. Multiple OSPF Extended Prefix
TLVs MAY be advertised in each OSPFv2 Extended Prefix Opaque LSA but
all prefixes included in a single OSPFv2 Extended Prefix Opaque LSA
MUST have the same flooding scope. The OSPF Extended Prefix TLV has
the following format:
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 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Route Type | Prefix Length | AF | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Prefix (variable) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
+- -+
| |
OSPFv2 Extended Prefix TLV
Type
The TLV type. Suggested value is 1.
Length
Variable dependent on sub-TLVs.
Route Type
Route type: type of the OSPF route. If the route type is 0
(unspecified), the information inside the OSPF External Prefix TLV
applies to the prefix regardless of prefix's route-type. This is
useful when prefix specific attributes are advertised by ax
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external entity, which is not aware of the route-type associated
with the prefix. Supported types are:
0 - unspecified
1 - intra-area
3 - inter-area
5 - external
7 - NSSA external
Prefix Length
Length in of the prefix in bits.
AF
Address family for the prefix. Currently, the only supported
value is 0 for IPv4 unicast.
Address Prefix
The prefix itself encoded as an even multiple of 32-bit words,
padded with zeroed bits as necessary. This encoding consumes
((PrefixLength + 31) / 32) 32-bit words. The default route is
represented by a prefix of length 0.
This document creates a registry for OSPF Extended Prefix sub-TLVs in
Section 6.
3. OSPFv2 Extended Link Opaque LSA
The OSPFv2 Extended Link Opaque LSA will be used to advertise
additional link attributes. Opaque LSAs are described in [OPAQUE].
The OSPFv2 Extended Link Opaque LSA has an area flooding scope.
Multiple OSPFv2 Extended Link Opaque LSAs can be advertised by a
single router in an area.
The format of the OSPFv2 Extended Link Opaque LSA is 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS age | Options | 10 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Opaque type | Instance |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS sequence number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS checksum | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- TLVs -+
| ... |
OSPFv2 Extended Link LSA
The Opaque type used by OSPFv2 Extended Link Opaque LSA is 8.
The format of the TLVs within the body of the OSPFv2 Extended Prefix
LSA is the same as Section 2.
3.1. OSPFv2 Extended Link TLV
OSPFv2 Extended Link TLV is used in order to advertise various
attributes of the link. It describes a single link and is
constructed of a set of Sub-TLVs. There are no ordering requirements
for the Sub-TLVs. Only one Extended Link TLV SHALL be advertised in
each Extended Link Opaque LSA, allowing for fine granularity changes
in the topology.
The Extended Link TLV has following format:
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link-Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Sub-TLVs (variable) |
+- -+
| |
OSPFv2 Extended Link TLV
Type
The TLV type. Suggested value is 1.
Length
Variable dependent on sub-TLVs.
Link-Type
Link-Type is defined in section A.4.2 of [OSPFV2].
Link-ID
Link-ID is defined in section A.4.2 of [OSPFV2].
Link Data
Link-Data is defined in section A.4.2 of [OSPFV2].
This document creates a registry for OSPF Extended Link sub-TLVs in
Section 6.
4. Backward Compatibility
Since opaque OSPFv2 LSAs are optional and backward compatible
[OPAQUE], the extensions described herein is fully backward
compatible. However, future OSPFv2 extensions utilizing these
extensions must address backward compatibility of the corresponding
functionality.
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5. Security Considerations
In general, new LSAs defined in this document are subject to the same
security concerns as those described in [OSPFV2]. Additionally,
implementations must assure that malformed TLV and Sub-TLV
permutations do not result in errors which cause hard OSPF failures.
6. IANA Considerations
This specification updates the Opaque Link-State Advertisements (LSA)
Option Types with the following values:
o 7 (IANA Preallocated) - OSPFv2 Extended Prefix Opaque LSA
o 8 (IANA preallocated) - OSPFv2 Extended Link Opaque LSA
This specification also creates four new registries:
o OSPF Extended Prefix LSA TLVs
o OSPF Extended Prefix TLV Sub-TLVs
o OSPF Extended Link LSA TLVs
o OSPF Extended Link TLV Sub-TLVs
6.1. OSPF Extended Prefix LSA TLV Registry
The OSPF Extend Prefix LSA TLV registry will define top-level TLVs
for Extended Prefix LSAs and should be placed in the existing OSPF
IANA registry. New values can be allocated via IETF Consensus or
IESG Approval.
The following initial values are allocated:
o 0 - Reserved
o 1 - OSPF Extended Prefix TLV
Types in the range 32768-33023 are for experimental use; these will
not be registered with IANA, and MUST NOT be mentioned by RFCs.
Types in the range 33023-65535 are not to be assigned at this time.
Before any assignments can be made in this range, there MUST be a
Standards Track RFC that specifies IANA Considerations that covers
the range being assigned.
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6.2. OSPF Extended Prefix TLV Sub-TLV Registry
The OSPF Extended Link LSA sub-TLV registry will define will define
sub-TLVs at any level of nesting for Extended Link LSAs and should be
placed in the existing OSPF IANA registry. New values can be
allocated via IETF Consensus or IESG Approval.
The following initial values are allocated:
o 0 - Reserved
Types in the range 32768-33023 are for experimental use; these will
not be registered with IANA, and MUST NOT be mentioned by RFCs.
Types in the range 33023-65535 are not to be assigned at this time.
Before any assignments can be made in this range, there MUST be a
Standards Track RFC that specifies IANA Considerations that covers
the range being assigned.
6.3. OSPF Extended Link LSA TLV Registry
The OSPF Extend Link LSA TLV registry will define top-level TLVs for
Extended Link LSAs and should be placed in the existing OSPF IANA
registry. New values can be allocated via IETF Consensus or IESG
Approval.
Following initial values are allocated:
o 0 - Reserved
o 1 - OSPFv2 Extended Link TLV
Types in the range 32768-33023 are for experimental use; these will
not be registered with IANA, and MUST NOT be mentioned by RFCs.
Types in the range 33023-65535 are not to be assigned at this time.
Before any assignments can be made in this range, there MUST be a
Standards Track RFC that specifies IANA Considerations that covers
the range being assigned.
6.4. OSPF Extended Link TLV Sub-TLV Registry
The OSPF Extended Link sub-TLV registry will define will define sub-
TLVs at any level of nesting for Extended Link LSAs and should be
placed in the existing OSPF IANA registry. New values can be
allocated via IETF Consensus or IESG Approval.
The following initial values are allocated:
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o 0 - Reserved
Types in the range 32768-33023 are for experimental use; these will
not be registered with IANA, and MUST NOT be mentioned by RFCs.
Types in the range 33023-65535 are not to be assigned at this time.
Before any assignments can be made in this range, there MUST be a
Standards Track RFC that specifies IANA Considerations that covers
the range being assigned.
7. References
7.1. Normative References
[OPAQUE] Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The
OSPF Opaque LSA Option", RFC 5250, July 2008.
[OSPFV2] Moy, J., "OSPF Version 2", RFC 2328, April 1998.
[RFC-KEYWORDS]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997.
[TE] Katz, D., Yeung, D., and K. Kompella, "Traffic Engineering
Extensions to OSPF", RFC 3630, September 2003.
7.2. Informative References
[OSPFV3-LSA-EXTEND]
Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3
LSA Extendibility", draft-ietf-ospf-multi-instance-02.txt
(work in progress).
Authors' Addresses
Peter Psenak
Cisco Systems
Apollo Business Center
Mlynske nivy 43
Bratislava, 821 09
Slovakia
Email: ppsenak@cisco.com
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Stefano Previdi
Cisco Systems
Via Del Serafico, 200
Rome, 00142
Italy
Email: sprevidi@cisco.com
Clarence Filsfils
Cisco Systems
Brussels
Belgium
Email: cfilsfils@cisco.com
Hannes Gredler
Juniper Networks, Inc.
1194 N. Mathilda Ave.
Sunnyvale, CA 94089
USA
Email: hannes@juniper.net
Rob Shakir
British Telcom
London
UK
Email: rob.shakir@bt.com
Wim Henderickx
Alcatel-Lucent
Copernicuslaan
Antwerp, 2018 94089
Belgium
Email: wim.henderickx@alcatel-lucent.com
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Jeff Tantsura
Ericsson
300 Holger Way
San Jose, CA 95134
USA
Email: jeff.tantsura@ericsson.com
Acee Lindem
Cisco Systems
301 Midenhall Way
Cary, NC 27513
USA
Email: acee@cisco.com
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