Network Working Group A. Lindem
Internet-Draft Ericsson
Intended status: Standards Track S. Mirtorabi
Expires: November 2, 2013 A. Roy
F. Baker
Cisco Systems
May 1, 2013
OSPFv3 LSA Extendibility
draft-acee-ospfv3-lsa-extend-00.txt
Abstract
OSPFv3 requires functional extension beyond what can be done with the
fixed Link State Advertisement (LSA) format as described in RFC 5340.
This document extends the LSA format by allowing the optional
inclusion of Type-Length-Value (TLV) tuples in the LSAs. It also
covers all the aspects of backward compatibility.
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-
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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 November 2, 2013.
Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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include Simplified BSD License text as described in Section 4.e of
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Requirements notation . . . . . . . . . . . . . . . . . . 3
1.2. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 3
2. OSPFv3 Extended LSA Types . . . . . . . . . . . . . . . . . . 4
3. OSPFv3 Extended LSA TLV . . . . . . . . . . . . . . . . . . . 5
4. OSPFv3 E-Router-LSA . . . . . . . . . . . . . . . . . . . . . 6
5. OSPFv3 E-Network-LSA . . . . . . . . . . . . . . . . . . . . . 8
6. OSPFv3 E-Inter-Area-Prefix-LSA . . . . . . . . . . . . . . . . 10
7. OSPFv3 E-Inter-Area-Router-LSA . . . . . . . . . . . . . . . . 12
8. OSPFv3 E-AS-External-LSA . . . . . . . . . . . . . . . . . . . 14
9. OSPFv3 E-NSSA-LSA . . . . . . . . . . . . . . . . . . . . . . 16
10. OSPFv3 E-Link-LSA . . . . . . . . . . . . . . . . . . . . . . 17
11. OSPFv3 E-Intra-Area-Prefix-LSA . . . . . . . . . . . . . . . . 20
12. LSA Extension Backward Compatibility . . . . . . . . . . . . . 21
12.1. LSA TLV Processing Backward Compatibility . . . . . . . . 22
13. Security Considerations . . . . . . . . . . . . . . . . . . . 23
14. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
15. References . . . . . . . . . . . . . . . . . . . . . . . . . . 25
15.1. Normative References . . . . . . . . . . . . . . . . . . . 25
15.2. Informative References . . . . . . . . . . . . . . . . . . 25
Appendix A. Configurable Constants . . . . . . . . . . . . . . . 26
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 27
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1. Introduction
OSPFv3 requires functional extension beyond what can be done with the
fixed Link State Advertisement (LSA) format as described in RFC 5340
[OSPFV3]. This document extends the LSA format by allowing the
optional inclusion of Type-Length-Value (TLV) tuples in the LSAs.
Backward compatibility mechanisms are also described.
A similar extension was previously proposed in support of multi-
topology routing. Additional requirements for OSPFv3 LSA extension
include source/destination routing, route tagging, and others.
A final requirement is to limit the changes to OSPFv3 to those
necessary for TLV-based LSAs. For the most part, the semantics of
existing OSPFv3 LSA are retained for their TLV-based successor LSAs
described herein. Additionally, encoding details, e.g., the
representation of IPv6 prefixes as described in section A.4.1 in RFC
5340 [OSPFV3], have been retained. This requirement was incorporated
the increase the expedience of IETF adoption and deployment.
The following aspects of OSPFv3 LSA extension are described:
1. Extended LSA Types
2. Extended LSA Formats
3. Backward Compatibility
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
OSPFv3 TLV-based LSAs were first proposed in "Multi-topology routing
in OSPFv3 (MT-OSPFv3)" [MT-OSPFV3].
The RFC text was produced using Marshall Rose's xml2rfc tool.
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2. OSPFv3 Extended LSA Types
In order to provide backward compatibility, new LSA codes must be
allocated. There are eight fixed format TLVs defined in RFC 5340
[OSPFV3]. For ease of implementation and debugging, the LSA function
codes are the same as the fixed-format LSAs only with an offset of
32. The alternative was to allocate a bit in the LSA Type indicating
the new LSA format. However, this would use one half the LSA
function codes space for the migration of the eight original fixed
format LSAs.
LSA function code LS Type Description
----------------------------------------------------
33 0x2021 E-Router-LSA
34 0x2022 E-Network-LSA
35 0x2023 E-Inter-Area-Prefix-LSA
36 0x2024 E-Inter-Area-Router-LSA
37 0x4025 E-AS-External-LSA
38 N/A Unused (Not to be allocated)
39 0x2027 E-Type-7-LSA
40 0x0028 E-Link-LSA
41 0x2029 E-Intra-Area-Prefix-LSA
OSPFv3 Extended LSA Types
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3. OSPFv3 Extended LSA TLV
The format of the TLVs within the body of the extended LSAs 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. 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
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. Unrecognized types are ignored.
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4. OSPFv3 E-Router-LSA
The E-Router-LSA has an LS Type of 0x2021 and will initially have the
same content as the Router-LSA, section 4.4.3.2 in [OSPFV3], only
fully extendable and represented as TLVs.
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 |0|0|1| 0x21 |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 |Nt|x|V|E|B| Options |
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+--+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Extended Router-LSA
All LSA Header fields are the same as defined for the Router-LSA.
The following top-level TLVs are defined:
o 0 - Reserved
o 1 - Router-Link TLV
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 (Router-Link) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | 0 | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor Interface ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Router-Link TLV
Like the existing Router-LSA, the LSA length is used to determine the
end of the LSA including TLVs. The Router-Link TLV is only
applicable to the E-Router-LSA. Inclusion in other Extended LSAs
MUST be ignored.
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5. OSPFv3 E-Network-LSA
The E-Network-LSA has an LS Type of 0x2022 and will initially have
the same content as the Network-LSA, section 4.4.3.3 in [OSPFV3],
only fully extendable and represented as TLVs.
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 |0|0|1| 0x22 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-Network-LSA
All LSA Header fields are the same as defined for the Network-LSA.
The following top-level TLVs are defined:
o 2 - Attached-Routers TLV
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 2 (Attached-Routers) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Adjacent Neighbor Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. Additional Adjacent Neighbors .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Attached-Routers TLV
There are two reasons for not having a separate TLV or sub-TLV for
each adjacent neighbor. The first is to discourage using the
E-Network-LSA for more than its current role of solely advertising
the routers attached to a multi-access network. Metric as well other
attributes of individual attached routers should be advertised in
their respective E-Router-LSAs. The second reason is that there is
only a single E-Network-LSA per multi-access link with the Link State
ID set to the Designated Router's Interface ID and, consequently,
compact encoding has been chosen since to decrease the likelihood of
the size of the E-Network-LSA requiring IPv6 fragmentation advertised
in an OSPFv3 Link State Update packet.
Like the existing Network-LSA, the LSA length is used to determine
the end of the LSA including TLVs. The Attached-Routers TLV is only
applicable to the E-Network-LSA. Inclusion in other Extended LSAs
MUST be ignored.
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6. OSPFv3 E-Inter-Area-Prefix-LSA
The E-Inter-Area-Prefix-LSA has an LS Type of 0x2023 and will
initially have the same content as the Inter-Area-Prefix-LSA, section
4.4.3.4 in [OSPFV3], only fully extendable and represented as TLVs.
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 |0|0|1| 0x23 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-Inter-Area-Prefix-LSA
All LSA Header fields are the same as defined for the Network-LSA.
The following top-level TLVs are defined:
o 3 - Inter-Area Prefix TLV
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 3 (Inter-Area Prefix) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PrefixLength | PrefixOptions | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Prefix |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inter-Area Prefix TLV
In order to retain compatibility and semantics with the current
OSPFv3 specification, each LSA will contain a single Inter-Area
Prefix TLV. This will facilitate migration and avoid changes to
functions such as incremental SPF computation.
Like the existing Inter-Area-Prefix-LSA, the LSA length is used to
determine the end of the LSA including TLV. The Inter-Area-Prefix
TLV is only applicable to the E-Inter-Area-Prefix-LSA. Inclusion in
other Extended LSAs MUST be ignored.
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7. OSPFv3 E-Inter-Area-Router-LSA
The E-Inter-Area-Router-LSA has an LS Type of 0x2024 and will
initially have the same content as the Inter-Area-Router-LSA, section
4.4.3.5 in [OSPFV3], only fully extendable and represented as TLVs.
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 |0|0|1| 0x24 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-Inter-Area-Router-LSA
All LSA Header fields are the same as defined for the Inter-Area-
Router-LSA. The following top-level TLVs are defined:
o 4 - Inter-Area Router TLV
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 3 (Inter-Area Router) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Destination Router ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Inter-Area Router TLV
In order to retain compatibility and semantics with the current
OSPFv3 specification, each LSA will contain a single Inter-Area
Router TLV. This will facilitate migration and avoid changes to
functions such as incremental SPF computation.
Like the existing Inter-Area-Router-LSA, the LSA length is used to
determine the end of the LSA including sub-TLVs. The Inter-Area-
Router TLV is only applicable to the E-Inter-Area-Router-LSA.
Inclusion in other Extended LSAs MUST be ignored.
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8. OSPFv3 E-AS-External-LSA
The E-AS-External-LSA has an LS Type of 0x4025 and will initially
have the same content as the AS-External-LSA, section 4.4.3.6 in
[OSPFV3], only fully extendable and represented as TLVs.
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 |0|1|0| 0x25 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-AS-External-LSA
All LSA Header fields are the same as defined for the AS-External-
LSA. The following top-level TLVs are defined:
o 5 - External Prefix TLV
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 5 (External Prefix) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |E|F|T| Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PrefixLength | PrefixOptions | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Prefix |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- -+
| |
+- Forwarding Address (Optional) -+
| |
+- -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| External Route Tag (Optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
External Prefix TLV
In order to retain compatibility and semantics with the current
OSPFv3 specification, each LSA will contain a single External Prefix
TLV. This will facilitate migration and avoid changes to functions
such as incremental SPF computation. Given the Referenced LS type
and Referenced Link State ID from the AS-External-LSA have never been
used or even specified, they have been omitted from the External
Prefix TLV. If there were ever a requirement for a referenced LSA,
it could be satisfied with a sub-TLV.
Like the existing AS-External-LSA, the LSA length is used to
determine the end of the LSA including sub-TLVs. The External-Prefix
TLV is only applicable to the E-AS-External-LSA and the E-NSSA-LSA.
Inclusion in other Extended LSAs MUST be ignored.
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9. OSPFv3 E-NSSA-LSA
The E-NSSA-LSA will have the same format and TLVs as the Extended AS-
External-LSA Section 8. This is the same relationship as exists
between the NSSA-LSA, section 4.4.3.7 in [OSPFV3], and the AS-
External-LSA. The NSSA-LSA will have type 0x2027 which implies area
flooding scope. Future requirements may dictate that supported TLVs
differ between the E-AS-External-LSA and the E-NSSA-TLV. However,
future requirements are beyond the scope of this document.
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10. OSPFv3 E-Link-LSA
The E-Link-LSA has an LS Type of 0x0028 and will initially have the
same content as the Link-LSA, section 4.4.3.8 in [OSPFV3], only fully
extendable and represented as TLVs.
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 |0|0|0| 0x28 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Rtr Priority | Options |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-Link-LSA
The following top-level TLVs are defined:
o 6 - Intra-Area Prefix TLV
o 7 - IPv6 Link-Local Address TLV
o 8 - IPv4 Link-Local Address TLV
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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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 6 (Intra-Area Prefix) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Metric |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| PrefixLength | PrefixOptions | 0 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Prefix |
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Intra-Area Prefix TLV
Like the Link-LSA, the E-Link-LSA affords advertisement of multiple
intra-area prefixes. Hence, multiple Intra-Area Prefix TLVs may be
specified and the LSA length defines the end of the LSA including all
TLVs. The Intra-Area-Prefix TLV is only applicable to the E-Link-LSA
and the E-Intra-Area-Prefix-LSA. Inclusion in other Extended LSAs
MUST be ignored.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 7 (IPv6 Local-Local Address) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+- -+
| |
+- IPv6 Link-Local Interface Address -+
| |
+- -+
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 Link-Local Address TLV
The IPv6 Link-Local Address TLV is to be used with IPv6 address
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families as defined in [OSPFV3-AF]. The IPv6 Link-Local Address TLV
is only applicable to the E-Link-LSA. Inclusion in other Extended
LSAs MUST be ignored. Only a single instance of the IPv6 Link-Local
Address family SHOULD be included in the E-Link-LSA. Instances
preceding the first MUST be ignored. For IPv4 address families as
defined in [OSPFV3-AF]. this TLV SHOULD be ignored. Future
specifications may support advertisement of routing and topology for
multiple address families. However, this is beyond the scope of this
document.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 8 (IPv4 Local-Local Address) | TLV Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 Link-Local Interface Address |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. sub-TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
IPv6 Link-Local Address TLV
The IPv4 Link-Local Address TLV is to be used with IPv4 address
families as defined in [OSPFV3-AF]. The IPv4 Link-Local Address TLV
is only applicable to the E-Link-LSA. Inclusion in other Extended
LSAs MUST be ignored. Only a single instance of the IPv4 Link-Local
Address family SHOULD be included in the E-Link-LSA. Instances
preceding the first MUST be ignored. For IPv6 address families as
defined in [OSPFV3-AF]. Future specifications may support
advertisement of routing and topology for multiple address families.
However, this is beyond the scope of this document.
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11. OSPFv3 E-Intra-Area-Prefix-LSA
The E-Intra-Area-Prefix-LSA has an LS Type of 0x2029 and will
initially have the same content as the Intra-Area-Prefix-LSA, section
4.4.3.9 in [OSPFV3], only fully extendable and represented as TLVs.
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 |0|0|1| 0x29 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| LS Checksum | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0 | Referenced LS Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Referenced Link State ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Referenced Advertising Router |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. .
. TLVs .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
E-Intra-Area-Prefix-LSA
All LSA Header fields are the same as defined for the Intra-Area-
Prefix-LSA. The following top-level TLVs are defined:
o 6 - Intra-Area-Prefix TLV (defined in Section 10)
Like the Intra-Area-Prefix-LSA, the E-Intra-Area-Link-LSA affords
advertisement of multiple intra-area prefixes. Hence, multiple
Intra-Area Prefix TLVs may be specified and the LSA length defines
the end of the LSA including all TLVs.
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12. LSA Extension Backward Compatibility
In the context of this document, backward compatibility is solely
related to the capability of an OSPFv3 router to receive, process,
and originate the TLV-based LSAs defined herein. Backward
compatility for future OSPFv3 extensions utilizing the TLV-based LSAs
is out of scope and must be covered in the documents describing those
extensions. Both full and, if applicable, partial deployment should
be covered for future OSPFv3 LSA extensions.
Given the radical change in encoding and the scalability impact of
having both the TLV and non-TLV based versions of the same LSAs
within a routing domain, mixed routing domains are not supported.
Networks requiring concurrent support for both OSPFv3 routers
utilizing TLV-based LSAs and OSPFv3 routers not supporting them will
need to do so with separate OSPFv3 routing domains and multiple
OSPFv3 instances. An OSPFv3 instance will be configured to use
either the TLV-based or Non-TLV-based LSAs (Appendix A). In order to
facilitate this separation, the OSPFv3 options field (as described in
Appendix A.2 of RFC 5340 [OSPFV3]), will contain an additional
options bits. The EL-bit will be used to indicate that the
advertising OSPFv3 Router can receive, process, and originate TLV-
based LSAs. A configured to support TLV-based LSAs WILL set its
option field EL-bit in OSPFv3 Hello and Database Description packets
and MUST NOT form adjacencies with OSPFv3 Routers sending OSPFv3
Hello and Database Description packets with the options field EL-bit
clear. In this manner, OSPFv3 routing domains utilizing the new
encoding will be completely isolated from those using the RFC 5340
encodings.
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
+-+-+-+-+-+-+-+-+-+-+-+-+--+--+-+--+-+-+--+-+-+-+--+--+
| | | | | | | | | | | | |EL|AT|L|AF|*|*|DC|R|N|x| E|V6|
+-+-+-+-+-+-+-+-+-+-+-+-+--+--+-+--+-+-+--+-+-+-+--+--+
The Options field
EL-bit
This bit is indicates whether or not the OSPFv3 router
supports the Extended LSA format with the bit set condition
indicating support.
Options Field EL-bit
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12.1. LSA TLV Processing Backward Compatibility
This section defines the general rules for processing LSA TLVs. To
ensure compatibility of future TLV-based LSA extensions, all
implementations MUST adhere to these rules:
1. Unrecognized TLVs and sub-TLVs are ignored when parsing or
processing Extended-LSAs.
2. Whether or not partial deployment of a given TLV is supported
MUST be specified.
3. If partial deployment is not supported, mechanisms to ensure the
corresponding feature are not deployed MUST be specified in the
document defining the new TLV or sub-TLV.
4. If partial deployment is supported, backward compatibility and
partial deployment MUST be specified in the document defining the
new TLV or sub-TLV.
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13. Security Considerations
Extendible OSPFv3 LSAs do not introduce any new security concerns
beyond those described in RFC 5340 [OSPFV3].
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14. IANA Considerations
This specification defines nine OSPFv3 Extended LSA types as
described in Section 2.
This specification also creates two registries OSPFv3 Extended-LSAs
TLVs and sub-TLVs. The TLV and Sub-TLV code-points in these
registries are common to all Extended-LSAs and their respective
definitions must define where they are applicable.
The OSPFv3 Extend-LSA TLV registry will define top-level TLVs for
Extended-LSAs and should be placed in the existing OSPFv3 IANA
registry. New values can be allocated via IETF Consensus or IESG
Approval.
Nine initial values are allocated:
o 0 - Reserved
o 1 - Router-Link TLV
o 2 - Attached-Routers TLV
o 3 - Inter-Area Prefix TLV
o 4 - Inter-Area Router TLV
o 5 - External Prefix TLV
o 6 - Intra-Area Prefix TLV
o 7 - IPv6 Link-Local Address TLV
o 8 - IPv4 Link-Local Address TLV
The OSPFv3 Extend-LSA sub-TLV registry will define sub-TLVs at any
level of nesting for Extended-LSAs and should be placed in the
existing OSPFv3 IANA registry. New values can be allocated via IETF
Consensus or IESG Approval.
One initial value is allocated:
o 0 - Reserved
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15. References
15.1. Normative References
[OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF
for IPv6", RFC 5340, July 2008.
[OSPFV3-AF]
Lindem, A., Mirtorabi, S., Roy, A., Barnes, M., and R.
Aggarwal, "Support of Address Families in OSPFv3",
RFC 5838, April 2010.
[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.
15.2. Informative References
[MT-OSPFV3]
Mirtorabi, S. and A. Roy, "Multi-toplogy routing in OSPFv3
(MT-OSPFV3)", draft-ietf-ospf-mt-ospfv3-04.txt (work in
progress).
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Appendix A. Configurable Constants
An additional global configurable constant will be added to the
OSPFv3 protocol.
ExtendedLSASupport
This is a boolean value indicating whether or not the OSPFv3
instance supports the TLV format described herein for Extended
LSAs. If this parameter is set, extended LSAs will be originated
and utilized in the Shortest Path First (SPF) calculation. Non-
extended LSAs will not be used in the SPF calculation and, if
received, will result the network operator being alerted.
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Authors' Addresses
Acee Lindem
Ericsson
102 Carric Bend Court
Cary, NC 27519
USA
Email: acee.lindem@ericsson.com
Sina Mirtorabi
Cisco Systems
170 Tasman Drive
San Jose, CA 95134
USA
Email: sina@cisco.com
Abhay Roy
Cisco Systems
170 Tasman Drive
San Jose, CA 95134
USA
Email: akr@cisco.com
Fred Baker
Cisco Systems
Santa Barbara, CA 93117
USA
Email: fred@cisco.com
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