Tech-invite3GPPspaceIETF RFCsSIP
929190898887868584838281807978777675747372717069686766656463626160595857565554535251504948474645444342414039383736353433323130292827262524232221201918171615141312111009080706050403020100
in Index   Prev   Next

RFC 8362

OSPFv3 Link State Advertisement (LSA) Extensibility

Pages: 33
Proposed Standard
Updates:  53405838
Part 2 of 2 – Pages 16 to 33
First   Prev   None

Top   ToC   RFC8362 - Page 16   prevText

4. OSPFv3 Extended LSAs

This section specifies the OSPFv3 Extended LSA formats and encoding. The Extended OSPFv3 LSAs corresponded directly to the original OSPFv3 LSAs specified in [OSPFV3].

4.1. OSPFv3 E-Router-LSA

The E-Router-LSA has an LS Type of 0xA021 and has the same base information content as the Router-LSA defined in Appendix A.4.3 of [OSPFV3]. However, unlike the existing Router-LSA, it is fully extensible and represented as TLVs.
Top   ToC   RFC8362 - Page 17
       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               |1|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

   Other than having a different LS Type, all LSA Header fields are the
   same as defined for the Router-LSA.  Initially, only the top-level
   Router-Link TLV (Section 3.2) is applicable, and an E-Router-LSA may
   include multiple Router-Link TLVs.  Like the existing Router-LSA, the
   LSA length is used to determine the end of the LSA including any
   TLVs.  Depending on the implementation, it is perfectly valid for an
   E-Router-LSA to not contain any Router-Link TLVs.  However, this
   would imply that the OSPFv3 router doesn't have any adjacencies in
   the corresponding area and is forming an adjacency or adjacencies
   over an unnumbered link(s).  Note that no E-Router-LSA stub link is
   advertised for an unnumbered link.
Top   ToC   RFC8362 - Page 18

4.2. OSPFv3 E-Network-LSA

The E-Network-LSA has an LS Type of 0xA022 and has the same base information content as the Network-LSA defined in Appendix A.4.4 of [OSPFV3]. However, unlike the existing Network-LSA, it is fully extensible 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 |1|0|1| 0x22 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 0 | Options | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E-Network-LSA Other than having a different LS Type, all LSA Header fields are the same as defined for the Network-LSA. Like the existing Network-LSA, the LSA length is used to determine the end of the LSA including any TLVs. Initially, only the top-level Attached-Routers TLV (Section 3.3) is applicable. If the Attached-Router TLV is not included in the E-Network-LSA, it is treated as malformed as described in Section 5. Instances of the Attached-Router TLV subsequent to the first MUST be ignored.
Top   ToC   RFC8362 - Page 19

4.3. OSPFv3 E-Inter-Area-Prefix-LSA

The E-Inter-Area-Prefix-LSA has an LS Type of 0xA023 and has the same base information content as the Inter-Area-Prefix-LSA defined in Appendix A.4.5 of [OSPFV3]. However, unlike the existing Inter-Area-Prefix-LSA, it is fully extensible 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 |1|0|1| 0x23 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E-Inter-Area-Prefix-LSA Other than having a different LS Type, all LSA Header fields are the same as defined for the Inter-Area-Prefix-LSA. In order to retain compatibility and semantics with the current OSPFv3 specification, each Inter-Area-Prefix LSA MUST contain a single Inter-Area-Prefix TLV. This will facilitate migration and avoid changes to functions such as incremental Shortest Path First (SPF) computation. Like the existing Inter-Area-Prefix-LSA, the LSA length is used to determine the end of the LSA including any TLVs. Initially, only the top-level Inter-Area-Prefix TLV (Section 3.4) is applicable. If the Inter-Area-Prefix TLV is not included in the E-Inter-Area-Prefix-LSA, it is treated as malformed as described in Section 5. Instances of the Inter-Area-Prefix TLV subsequent to the first MUST be ignored.
Top   ToC   RFC8362 - Page 20

4.4. OSPFv3 E-Inter-Area-Router-LSA

The E-Inter-Area-Router-LSA has an LS Type of 0xA024 and has the same base information content as the Inter-Area-Router-LSA defined in Appendix A.4.6 of [OSPFV3]. However, unlike the Inter-Area-Router-LSA, it is fully extensible 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 |1|0|1| 0x24 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E-Inter-Area-Router-LSA Other than having a different LS Type, all LSA Header fields are the same as defined for the Inter-Area-Router-LSA. In order to retain compatibility and semantics with the current OSPFv3 specification, each Inter-Area-Router-LSA MUST 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 any TLVs. Initially, only the top-level Inter-Area-Router TLV (Section 3.5) is applicable. If the Inter-Area-Router TLV is not included in the E-Inter-Area-Router-LSA, it is treated as malformed as described in Section 5. Instances of the Inter-Area-Router TLV subsequent to the first MUST be ignored.
Top   ToC   RFC8362 - Page 21

4.5. OSPFv3 E-AS-External-LSA

The E-AS-External-LSA has an LS Type of 0xC025 and has the same base information content as the AS-External-LSA defined in Appendix A.4.7 of [OSPFV3]. However, unlike the existing AS-External-LSA, it is fully extensible 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 |1|1|0| 0x25 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E-AS-External-LSA Other than having a different LS Type, all LSA Header fields are the same as defined for the AS-External-LSA. In order to retain compatibility and semantics with the current OSPFv3 specification, each LSA MUST contain a single External-Prefix TLV. This will facilitate migration and avoid changes to OSPFv3 functions such as incremental SPF computation. Like the existing AS-External-LSA, the LSA length is used to determine the end of the LSA including any TLVs. Initially, only the top-level External-Prefix TLV (Section 3.6) is applicable. If the External-Prefix TLV is not included in the E-External-AS-LSA, it is treated as malformed as described in Section 5. Instances of the External-Prefix TLV subsequent to the first MUST be ignored.
Top   ToC   RFC8362 - Page 22

4.6. OSPFv3 E-NSSA-LSA

The E-NSSA-LSA will have the same format and TLVs as the Extended AS-External-LSA (Section 4.5). This is the same relationship that exists between the NSSA-LSA, as defined in Appendix A.4.8 of [OSPFV3], and the AS-External-LSA. The NSSA-LSA will have type 0xA027, which implies area flooding scope. Future requirements may dictate that supported TLVs differ between the E-AS-External-LSA and the E-NSSA-LSA. However, future requirements are beyond the scope of this document.

4.7. OSPFv3 E-Link-LSA

The E-Link-LSA has an LS Type of 0x8028 and will have the same base information content as the Link-LSA defined in Appendix A.4.9 of [OSPFV3]. However, unlike the existing Link-LSA, it is fully extensible 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 |1|0|0| 0x28 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Link State ID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Advertising Router | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Sequence Number | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | LS Checksum | Length | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Rtr Priority | Options | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ . . . TLVs . . . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ E-Link-LSA Other than having a different LS Type, all LSA Header fields are the same as defined for the Link-LSA. Only the Intra-Area-Prefix TLV (Section 3.7), IPv6 Link-Local Address TLV (Section 3.8), and IPv4 Link-Local Address TLV (Section 3.9) are applicable to the E-Link-LSA. Like the Link-LSA, the E-Link-LSA
Top   ToC   RFC8362 - Page 23
   affords advertisement of multiple intra-area prefixes.  Hence,
   multiple Intra-Area-Prefix TLVs (Section 3.7) may be specified, and
   the LSA length defines the end of the LSA including any TLVs.

   A single instance of the IPv6 Link-Local Address TLV (Section 3.8)
   SHOULD be included in the E-Link-LSA.  Instances following the first
   MUST be ignored.  For IPv4 address families as defined in
   [OSPFV3-AF], this TLV MUST be ignored.

   Similarly, only a single instance of the IPv4 Link-Local Address TLV
   (Section 3.9) SHOULD be included in the E-Link-LSA.  Instances
   following the first MUST be ignored.  For OSPFv3 IPv6 address
   families as defined in [OSPFV3-AF], this TLV SHOULD be ignored.

   If the IPv4/IPv6 Link-Local Address TLV corresponding to the OSPFv3
   Address Family is not included in the E-Link-LSA, it is treated as
   malformed as described in Section 5.

   Future specifications may support advertisement of routing and
   topology information for multiple address families.  However, this is
   beyond the scope of this document.
Top   ToC   RFC8362 - Page 24

4.8. OSPFv3 E-Intra-Area-Prefix-LSA

The E-Intra-Area-Prefix-LSA has an LS Type of 0xA029 and has the same base information content as the Intra-Area-Prefix-LSA defined in Appendix A.4.10 of [OSPFV3] except for the Referenced LS Type. However, unlike the Intra-Area-Prefix-LSA, it is fully extensible and represented as TLVs. The Referenced LS Type MUST be either an E-Router-LSA (0xA021) or an E-Network-LSA (0xA022). 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 |1|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 Other than having a different LS Type, all LSA Header fields are the same as defined for the Intra-Area-Prefix-LSA. 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 any TLVs.
Top   ToC   RFC8362 - Page 25

5. Malformed OSPFv3 Extended LSA Handling

Extended LSAs that have inconsistent length or other encoding errors, as described herein, MUST NOT be installed in the Link State Database, acknowledged, or flooded. Reception of malformed LSAs SHOULD be counted and/or logged for examination by the administrator of the OSPFv3 routing domain. Note that for the purposes of length validation, a TLV or sub-TLV should not be considered invalid unless the length exceeds the length of the LSA or does not meet the minimum length requirements for the TLV or sub-TLV. This allows for sub-TLVs to be added as described in Section 6.3. Additionally, an LSA MUST be considered malformed if it does not include all of the required TLVs and sub-TLVs.

6. 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. Unrecognized TLVs and sub-TLVs are ignored. Backward compatibility 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 specified for future TLV- based OSPFv3 LSA extensions.

6.1. Full Extended LSA Migration

If ExtendedLSASupport is enabled (Appendix A), OSPFv3 Extended LSAs will be originated and used for the SPF computation. Individual OSPF Areas can be migrated separately with the Legacy AS-External-LSAs being originated and used for the SPF computation. This is accomplished by enabling AreaExtendedLSASupport (Appendix B). An OSPFv3 routing domain or area may be non-disruptively migrated using separate OSPFv3 instances for the Extended LSAs. Initially, the OSPFv3 instances with ExtendedLSASupport will have a lower preference, i.e., higher administrative distance, than the OSPFv3 instances originating and using the Legacy LSAs. Once the routing domain or area is fully migrated and the OSPFv3 Routing Information Bases (RIBs) have been verified, the OSPFv3 instances using the Extended LSAs can be given preference. When this has been completed and the routing within the OSPF routing domain or area has been verified, the original OSPFv3 instance using Legacy LSAs can be removed.
Top   ToC   RFC8362 - Page 26

6.2. Extended LSA Sparse-Mode Backward Compatibility

In this mode, OSPFv3 will use the Legacy LSAs for the SPF computation and will only originate Extended LSAs when LSA origination is required in support of additional functionality. Furthermore, those Extended LSAs will only include the top-level TLVs (e.g., Router-Link TLVs or Inter-Area TLVs), which are required for that new functionality. However, if a top-level TLV is advertised, it MUST include required sub-TLVs, or it will be considered malformed as described in Section 5. Hence, this mode of compatibility is known as "sparse-mode". The advantage of sparse-mode is that functionality utilizing the OSPFv3 Extended LSAs can be added to an existing OSPFv3 routing domain without the requirement for migration. In essence, this compatibility mode is very much like the approach taken for OSPFv2 [OSPF-PREFIX-LINK]. As with all the compatibility modes, backward compatibility for the functions utilizing the Extended LSAs must be described in the IETF documents describing those functions.

6.3. 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 is 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. 5. If a TLV or sub-TLV is recognized but the length is less than the minimum, then the LSA should be considered malformed, and it SHOULD NOT be acknowledged. Additionally, the occurrence SHOULD be logged with enough information to identify the LSA by type, Link State ID, originator, and sequence number and identify the TLV or sub-TLV in error. Ideally, the log entry would include the hexadecimal or binary representation of the LSA including the malformed TLV or sub-TLV.
Top   ToC   RFC8362 - Page 27
   6.  Documents specifying future TLVs or Sub-TLVs MUST specify the
       requirements for usage of those TLVs or sub-TLVs.

   7.  Future TLVs or sub-TLVs must be optional.  However, there may be
       requirements for sub-TLVs if an optional TLV is specified.

7. Security Considerations

In general, extensible OSPFv3 LSAs are subject to the same security concerns as those described in RFC 5340 [OSPFV3]. Additionally, implementations must assure that malformed TLV and sub-TLV permutations do not result in errors that cause hard OSPFv3 failures. If there were ever a requirement to digitally sign OSPFv3 LSAs as described for OSPFv2 LSAs in RFC 2154 [OSPF-DIGITAL-SIGNATURE], the mechanisms described herein would greatly simplify the extension.

8. IANA Considerations

This specification defines nine OSPFv3 Extended LSA types as described in Section 2. These have been added to the existing OSPFv3 LSA Function Codes registry. The specification defines a code point for the N-bit in the OSPFv3 Prefix-Options registry. The value 0x20 has been assigned. This specification also creates two registries for OSPFv3 Extended LSA 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.

8.1. OSPFv3 Extended LSA TLV Registry

The "OSPFv3 Extended LSA TLVs" registry defines top-level TLVs for Extended LSAs and has been placed in the existing OSPFv3 IANA registry. Nine values have been 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
Top   ToC   RFC8362 - Page 28
   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

   Types in the range 9-32767 are allocated via IETF Review or IESG
   Approval [RFC8126].

   Types in the range 32768-33023 are Reserved for Experimental Use;
   these will not be registered with IANA and MUST NOT be mentioned by
   RFCs.

   Types in the range 33024-45055 are to be assigned on a First Come
   First Served (FCFS) basis.

   Types in the range 45056-65535 are not to be assigned at this time.
   Before any assignments can be made in the 33024-65535 range, there
   MUST be an IETF specification that specifies IANA Considerations that
   cover the range being assigned.

8.2. OSPFv3 Extended LSA Sub-TLV Registry

The "OSPFv3 Extended LSA Sub-TLVs" registry defines sub-TLVs at any level of nesting for Extended LSAs and has been placed in the existing OSPFv3 IANA registry. Four values have been allocated: o 0 - Reserved o 1 - IPv6-Forwarding-Address sub-TLV o 2 - IPv4-Forwarding-Address sub-TLV o 3 - Route-Tag sub-TLV Types in the range 4-32767 are allocated via IETF Review or IESG Approval. Types in the range 32768-33023 are Reserved for Experimental Use; these will not be registered with IANA and MUST NOT be mentioned by RFCs. Types in the range 33024-45055 are to be assigned on an FCFS basis.
Top   ToC   RFC8362 - Page 29
   Types in the range 45056-65535 are not to be assigned at this time.
   Before any assignments can be made in the 33024-65535 range, there
   MUST be an IETF specification that specifies IANA Considerations that
   cover the range being assigned.

9. References

9.1. Normative References

[NSSA] Murphy, P., "The OSPF Not-So-Stubby Area (NSSA) Option", RFC 3101, DOI 10.17487/RFC3101, January 2003, <https://www.rfc-editor.org/info/rfc3101>. [OSPFV3] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, DOI 10.17487/RFC5340, July 2008, <https://www.rfc-editor.org/info/rfc5340>. [OSPFV3-AF] Lindem, A., Ed., Mirtorabi, S., Roy, A., Barnes, M., and R. Aggarwal, "Support of Address Families in OSPFv3", RFC 5838, DOI 10.17487/RFC5838, April 2010, <https://www.rfc-editor.org/info/rfc5838>. [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, <https://www.rfc-editor.org/info/rfc8126>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>. [TE] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering (TE) Extensions to OSPF Version 2", RFC 3630, DOI 10.17487/RFC3630, September 2003, <https://www.rfc-editor.org/info/rfc3630>.
Top   ToC   RFC8362 - Page 30

9.2. Informative References

[IPV6-ADDRESS-ARCH] Hinden, R. and S. Deering, "IP Version 6 Addressing Architecture", RFC 4291, DOI 10.17487/RFC4291, February 2006, <https://www.rfc-editor.org/info/rfc4291>. [MT-OSPFV3] Mirtorabi, S. and A. Roy, "Multi-topology routing in OSPFv3 (MT-OSPFv3)", Work in Progress, draft-ietf-ospf-mt- ospfv3-03, July 2007. [OSPF-DIGITAL-SIGNATURE] Murphy, S., Badger, M., and B. Wellington, "OSPF with Digital Signatures", RFC 2154, DOI 10.17487/RFC2154, June 1997, <https://www.rfc-editor.org/info/rfc2154>. [OSPF-PREFIX-LINK] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 2015, <https://www.rfc-editor.org/info/rfc7684>. [SEGMENT-ROUTING] Psenak, P., Previdi, S., Filsfils, C., Gredler, H., Shakir, R., Henderickx, W., and J. Tantsura, "OSPFv3 Extensions for Segment Routing", Work in Progress, draft-ietf-ospf-ospfv3-segment-routing-extensions-11, January 2018.
Top   ToC   RFC8362 - Page 31

Appendix A. Global Configuration Parameters

The global configurable parameter ExtendedLSASupport is added to the OSPFv3 protocol. If ExtendedLSASupport is enabled, the OSPFv3 router will originate OSPFv3 Extended LSAs and use the LSAs for the SPF computation. If ExtendedLSASupport is not enabled, a subset of OSPFv3 Extended LSAs may still be originated and used for other functions as described in Section 6.2.

Appendix B. Area Configuration Parameters

The area configurable parameter AreaExtendedLSASupport is added to the OSPFv3 protocol. If AreaExtendedLSASupport is enabled, the OSPFv3 router will originate link and area OSPFv3 Extended LSAs and use the LSAs for the SPF computation. Legacy AS-Scoped LSAs will still be originated and used for the AS-External-LSA computation. If AreaExtendedLSASupport is not enabled, a subset of OSPFv3 link and area Extended LSAs may still be originated and used for other functions as described in Section 6.2. For regular areas, i.e., areas where AS-scoped LSAs are flooded, disabling AreaExtendedLSASupport for a regular OSPFv3 area (not a Stub or NSSA area) when ExtendedLSASupport is enabled is contradictory and SHOULD be prohibited by implementations.
Top   ToC   RFC8362 - Page 32

Acknowledgments

OSPFv3 TLV-based LSAs were first proposed in "Multi-topology routing in OSPFv3 (MT-OSPFv3)" [MT-OSPFV3]. Thanks for Peter Psenak for significant contributions to the backward-compatibility mechanisms. Thanks go to Michael Barnes, Mike Dubrovsky, Anton Smirnov, and Tony Przygienda for review of the draft versions and discussions of backward compatibility. Thanks to Alan Davey for review and comments including the suggestion to separate the Extended LSA TLV definitions from the Extended LSAs definitions. Thanks to David Lamparter for review and suggestions on backward compatibility. Thanks to Karsten Thomann, Chris Bowers, Meng Zhang, and Nagendra Kumar for review and editorial comments. Thanks to Alia Atlas for substantive Routing Area Director (AD) comments prior to IETF last call. Thanks to Alvaro Retana and Suresh Krishnan for substantive comments during IESG Review. Thanks to Mehmet Ersue for the Operations and Management (OPS) Directorate review.

Contributors

Sina Mirtorabi Cisco Systems 170 Tasman Drive San Jose, CA 95134 United States of America Email: sina@cisco.com
Top   ToC   RFC8362 - Page 33

Authors' Addresses

Acee Lindem Cisco Systems 301 Midenhall Way Cary, NC 27513 United States of America Email: acee@cisco.com Abhay Roy Cisco Systems 170 Tasman Drive San Jose, CA 95134 United States of America Email: akr@cisco.com Dirk Goethals Nokia Copernicuslaan 50 Antwerp 2018 Belgium Email: dirk.goethals@nokia.com Veerendranatha Reddy Vallem Bangalore India Email: vallem.veerendra@gmail.com Fred Baker Santa Barbara, California 93117 United States of America Email: FredBaker.IETF@gmail.com