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Internet Engineering Task Force (IETF)                    A. Lindem, Ed.Request for Comments: 7770                                       N. ShenObsoletes:4970                                              JP. VasseurCategory: Standards Track                                  Cisco SystemsISSN: 2070-1721                                              R. Aggarwal                                                                  Arktan                                                              S. Shaffer                                                                  Akamai                                                           February 2016Extensions to OSPF for Advertising Optional Router CapabilitiesAbstract   It is useful for routers in an OSPFv2 or OSPFv3 routing domain to   know the capabilities of their neighbors and other routers in the   routing domain.  This document proposes extensions to OSPFv2 and   OSPFv3 for advertising optional router capabilities.  The Router   Information (RI) Link State Advertisement (LSA) is defined for this   purpose.  In OSPFv2, the RI LSA will be implemented with an Opaque   LSA type ID.  In OSPFv3, the RI LSA will be implemented with a unique   LSA type function code.  In both protocols, the RI LSA can be   advertised at any of the defined flooding scopes (link, area, or   autonomous system (AS)).  This document obsoletesRFC 4970 by   providing a revised specification that includes support for   advertisement of multiple instances of the RI LSA and a TLV for   functional capabilities.Status of This Memo   This is an Internet Standards Track document.   This document is a product of the Internet Engineering Task Force   (IETF).  It represents the consensus of the IETF community.  It has   received public review and has been approved for publication by the   Internet Engineering Steering Group (IESG).  Further information on   Internet Standards is available inSection 2 of RFC 5741.   Information about the current status of this document, any errata,   and how to provide feedback on it may be obtained athttp://www.rfc-editor.org/info/rfc7770.Lindem, et al.               Standards Track                    [Page 1]

RFC 7770               OSPF Capability Extensions          February 2016Copyright Notice   Copyright (c) 2016 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents   (http://trustee.ietf.org/license-info) in effect on the date of   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   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 Contents1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .31.1.  Requirements Notation . . . . . . . . . . . . . . . . . .31.2.  Summary of Changes fromRFC 4970  . . . . . . . . . . . .32.  OSPF Router Information (RI) LSA  . . . . . . . . . . . . . .42.1.  OSPFv2 Router Information (RI) Opaque LSA . . . . . . . .42.2.  OSPFv3 Router Information (RI) Opaque LSA . . . . . . . .52.3.  OSPF Router Information LSA TLV Format  . . . . . . . . .62.4.  OSPF Router Informational Capabilities TLV  . . . . . . .62.5.  Assigned OSPF Router Informational Capability Bits  . . .72.6.  OSPF Router Functional Capabilities TLV . . . . . . . . .82.7.  Flooding Scope of the Router Information LSA  . . . . . .93.  Backwards Compatibility . . . . . . . . . . . . . . . . . . .94.  Security Considerations . . . . . . . . . . . . . . . . . . .95.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .105.1.  OSPFv2 Opaque LSA Type Assignment . . . . . . . . . . . .105.2.  OSPFv3 LSA Function Code Assignment . . . . . . . . . . .105.3.  OSPF RI LSA TLV Type Assignment . . . . . . . . . . . . .11     5.4.  Registry for OSPF Router Informational Capability Bits  .  125.5.  Registry for OSPF Router Functional Capability Bits . . .126.  References  . . . . . . . . . . . . . . . . . . . . . . . . .126.1.  Normative References  . . . . . . . . . . . . . . . . . .126.2.  Informative References  . . . . . . . . . . . . . . . . .13   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .14   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .15Lindem, et al.               Standards Track                    [Page 2]

RFC 7770               OSPF Capability Extensions          February 20161.  Introduction   It is useful for routers in an OSPFv2 [OSPF] or OSPFv3 [OSPFv3]   routing domain to know the capabilities of their neighbors and other   routers in the routing domain.  This can be useful for both the   advertisement and discovery of OSPFv2 and OSPFv3 capabilities.   Throughout this document, OSPF will be used when the specification is   applicable to both OSPFv2 and OSPFv3.  Similarly, OSPFv2 or OSPFv3   will be used when the text is protocol specific.   OSPF uses the options field in LSAs and hello packets to advertise   optional router capabilities.  In the case of OSPFv2, all the bits in   this field have been allocated so additional optional capabilities   cannot be advertised.  This document describes extensions to OSPF to   advertise these optional capabilities via Opaque LSAs in OSPFv2 and   LSAs with a unique type in OSPFv3.  For existing OSPF capabilities,   backwards compatibility issues dictate that this advertisement is   used primarily for informational purposes.  For future OSPF   extensions, this advertisement MAY be used as the sole mechanism for   advertisement and discovery.   This document obsoletesRFC 4970 by providing a revised specification   including support for advertisement of multiple instances of the RI   LSA and a TLV for functional capabilities.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.  Summary of Changes fromRFC 4970   This document includes the following changes fromRFC 4970 [RFC4970]:   1. The main change is that an OSPF router will be able to advertise      multiple instances of the OSPF Router Information LSA.  This      change permeates through much of the document.   2. Additionally,Section 2.6 includes an additional TLV for      functional capabilities.  This is in contrast to the existing TLV      that is used to advertise capabilities for informational purposes      only.Lindem, et al.               Standards Track                    [Page 3]

RFC 7770               OSPF Capability Extensions          February 2016   3. The IANA allocation policy has been changed from "Standards      Action" to "IETF Review" [IANA-GUIDE] for the following      registries:      o  OSPFv3 LSA Function Codes      o  OSPF Router Information (RI) TLVs      o  OSPF Router Informational Capability Bits      o  OSPF Router Functional Capability Bits   4. Finally, references have been updated for documents that have      become RFCs and RFCs that have been obsoleted since the      publication ofRFC 4970.2.  OSPF Router Information (RI) LSA2.1.  OSPFv2 Router Information (RI) Opaque LSA   OSPFv2 routers will advertise a link scoped, area-scoped, or AS-   scoped Opaque LSA [OPAQUE].  The OSPFv2 RI LSA has an Opaque type of   4 and the Opaque ID is the RI LSA Instance ID.  The first Opaque ID,   i.e., 0, SHOULD always contain the Router Informational Capabilities   TLV and, if advertised, the Router Functional Capabilities TLV.  RI   LSA instances subsequent to the first can be used for information   that doesn't fit in the first instance.   OSPFv2 routers will advertise a link-scoped, area-scoped, or AS-   scoped Opaque LSA [OPAQUE].  The OSPFv2 Router Information LSA has an   Opaque type of 4.  The Opaque ID specifies the LSA Instance ID with   the first instance always having an Instance ID of 0.       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 |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |       4       |     Opaque ID (Instance ID)                   |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+d-+-+-+-+-+-+-+-+-+-+-+      |                     Advertising Router                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                     LS sequence number                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |         LS checksum           |             length            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                                                               |      +-                            TLVs                             -+      |                             ...                               |                Figure 1.  OSPFv2 Router Information Opaque LSALindem, et al.               Standards Track                    [Page 4]

RFC 7770               OSPF Capability Extensions          February 2016   The format of the TLVs within the body of an RI LSA is as defined inSection 2.3.2.2.  OSPFv3 Router Information (RI) Opaque LSA   The OSPFv3 Router Information LSA has a function code of 12 while the   S1/S2 bits are dependent on the desired flooding scope for the LSA.   The U bit will be set indicating that the OSPFv3 RI LSA should be   flooded even if it is not understood.  The Link State ID (LSID) value   for this LSA is the Instance ID.  The first Instance ID, i.e., 0,   SHOULD always contain the Router Informational Capabilities TLV and,   if advertised, the Router Functional Capabilities TLV.  OSPFv3 Router   Information LSAs subsequent to the first can be used for information   that doesn't fit in the first instance.  OSPFv3 routers MAY advertise   multiple RI LSAs per flooding scope.       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|S12|          12             |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                       Link State ID (Instance ID)             |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                       Advertising Router                      |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                       LS sequence number                      |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |        LS checksum            |            Length             |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |                                                               |      +-                            TLVs                             -+      |                             ...                               |                  Figure 2.  OSPFv3 Router Information LSA   The format of the TLVs within the body of an RI LSA is as defined inSection 2.3Lindem, et al.               Standards Track                    [Page 5]

RFC 7770               OSPF Capability Extensions          February 20162.3.  OSPF Router Information LSA TLV Format   The format of the TLVs within the body of an RI LSA is the same as   the format used by the Traffic Engineering Extensions to OSPF [TE].   The LSA payload consists of one or more nested Type/Length/Value   (TLV) triplets.  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...                           |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+                             Figure 3.  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 4-octet   aligned.  For example, a 1-octet 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.  The padding is composed of undefined bits.   Unrecognized types are ignored.   When a new Router Information LSA TLV is defined, the specification   MUST explicitly state whether the TLV is applicable to OSPFv2 only,   OSPFv3 only, or both OSPFv2 and OSPFv3.2.4.  OSPF Router Informational Capabilities TLV   An OSPF router advertising an OSPF RI LSA MAY include the Router   Informational Capabilities TLV.  If included, it MUST be the first   TLV in the first instance, i.e., Instance 0, of the OSPF RI LSA.   Additionally, the TLV MUST accurately reflect the OSPF router's   capabilities in the scope advertised.  However, the informational   capabilities advertised have no impact on OSPF protocol operation;   they are advertised purely for informational purposes.Lindem, et al.               Standards Track                    [Page 6]

RFC 7770               OSPF Capability Extensions          February 2016   The format of the Router Informational Capabilities TLV 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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |              Type             |             Length            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |             Informational Capabilities                        |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type     A 16-bit field set to 1.      Length   A 16-bit field that indicates the length of the value               portion in octets and will be a multiple of 4 octets               dependent on the number of capabilities advertised.               Initially, the length will be 4, denoting 4 octets of               informational capability bits.      Value    A variable-length sequence of capability bits rounded to               a multiple of 4 octets padded with undefined bits.               Initially, there are 4 octets of capability bits.  Bits               are numbered left to right starting with the most               significant bit being bit 0.           Figure 4.  OSPF Router Informational Capabilities TLV   The Router Informational Capabilities TLV MAY be followed by optional   TLVs that further specify a capability.2.5.  Assigned OSPF Router Informational Capability Bits   The following informational capability bits have been assigned:      Bit       Capabilities      0         OSPF graceful restart capable [GRACE]      1         OSPF graceful restart helper  [GRACE]      2         OSPF Stub Router support [STUB]      3         OSPF Traffic Engineering support [TE]      4         OSPF point-to-point over LAN [P2PLAN]      5         OSPF Experimental TE [EXP-TE]      6-31      Unassigned (IETF Review)      Figure 5.  OSPF Router Informational Capabilities Bits   References for [GRACE], [STUB], [TE], [P2PLAN], and [EXP-TE] are   included herein.Lindem, et al.               Standards Track                    [Page 7]

RFC 7770               OSPF Capability Extensions          February 20162.6.  OSPF Router Functional Capabilities TLV   This specification also defines the Router Functional Capabilities   TLV for advertisement in the OSPF Router Information LSA.  An OSPF   router advertising an OSPF RI LSA MAY include the Router Functional   Capabilities TLV.  If included, it MUST be the included in the first   instance of the LSA.  Additionally, the TLV MUST reflect the   advertising OSPF router's actual functional capabilities since the   information will be used to dictate OSPF protocol operation in the   flooding scope of the containing OSPF RI LSA.  If the TLV is not   included or the length doesn't include the assigned OSPF functional   capability bit, the corresponding OSPF functional capability is   implicitly advertised as not being supported by the advertising OSPF   router.   The format of the Router Functional Capabilities TLV 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      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |              Type             |             Length            |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      |             Functional Capabilities                           |      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+      Type     A 16-bit field set to 2.      Length   A 16-bit field that indicates the length of the value               portion in octets and will be a multiple of 4 octets               dependent on the number of capabilities advertised.               Initially, the length will be 4, denoting 4 octets of               informational capability bits.      Value    A variable-length sequence of capability bits rounded               to a multiple of 4 octets padded with undefined bits.               Initially, there are 4 octets of capability bits.  Bits               are numbered left to right starting with the most               significant bit being bit 0.             Figure 6.  OSPF Router Functional Capabilities TLV   The Router Functional Capabilities TLV MAY be followed by optional   TLVs that further specify a capability.  In contrast to the Router   Informational Capabilities TLV, the OSPF extensions advertised in   this TLV MAY be used by other OSPF routers to dictate protocol   operation.  The specifications for functional capabilities advertised   in this TLV MUST describe protocol behavior and address backwards   compatibility.Lindem, et al.               Standards Track                    [Page 8]

RFC 7770               OSPF Capability Extensions          February 20162.7.  Flooding Scope of the Router Information LSA   The flooding scope for a Router Information LSA is determined by the   LSA type.  For OSPFv2, a type 9 (link-scoped), type 10 (area-scoped),   or type 11 (AS-scoped) Opaque LSA may be flooded.  For OSPFv3, the S1   and S2 bits in the LSA type determine the flooding scope.  If AS-wide   flooding scope is chosen, the originating router should also   advertise area-scoped LSA(s) into any attached Not-So-Stubby Area   (NSSA) area(s).  An OSPF router MAY advertise different capabilities   when both NSSA area-scoped LSA(s) and an AS-scoped LSA are   advertised.  This allows functional capabilities to be limited in   scope.  For example, a router may be an area border router but only   support traffic engineering (TE) in a subset of its attached areas.   The choice of flooding scope is made by the advertising router and is   a matter of local policy.  The originating router MAY advertise   multiple RI LSAs with the same Instance ID as long as the flooding   scopes differ.  TLV flooding-scope rules will be specified on a per-   TLV basis and MUST be specified in the accompanying specifications   for future Router Information LSA TLVs.3.  Backwards Compatibility   For backwards compatibility, previously advertised Router Information   TLVs SHOULD continue to be advertised in the first instance, i.e., 0,   of the Router Information LSA.  If a Router Information TLV is   advertised in multiple Router Information LSA instances and the   multiple instance processing is not explicitly specified in the RFC   defining that Router Information TLV, the Router Instance TLV in the   Router Information LSA with the numerically smallest Instance ID will   be used and subsequent instances will be ignored.4.  Security Considerations   This document describes both a generic mechanism for advertising   router capabilities and TLVs for advertising informational and   functional capabilities.  The capability TLVs are less critical than   the topology information currently advertised by the base OSPF   protocol.  The security considerations for the generic mechanism are   dependent on the future application and, as such, should be described   as additional capabilities are proposed for advertisement.  Security   considerations for the base OSPF protocol are covered in [OSPF] and   [OSPFv3].Lindem, et al.               Standards Track                    [Page 9]

RFC 7770               OSPF Capability Extensions          February 20165.  IANA Considerations5.1.  OSPFv2 Opaque LSA Type Assignment   [RFC4970] defined the Router Information Opaque LSA as type 4 in the   "Opaque Link-State Advertisements (LSA) Option Types" registry.  IANA   has updated the reference for that entry to point to this RFC.5.2.  OSPFv3 LSA Function Code Assignment   [RFC4970] created the registry for "OSPFv3 LSA Function Codes".  IANA   has updated the reference for that registry to point to this RFC.   References within that registry to [RFC4970] have been updated to   point to this RFC; references to other RFCs are unchanged.   The definition and assignment policy has been updated as follows.   This registry is now comprised of the fields Value, LSA Function Code   Name, and Reference.  The OSPFv3 LSA function code is defined inAppendix A.4.2.1 of [OSPFv3].  Values 1-11 and 13-15 have already   been assigned.  The OSPFv3 LSA function code 12 has been assigned to   the OSPFv3 Router Information (RI) LSA as defined herein.         +-----------+-------------------------------------+         | Range     | Assignment Policy                   |         +-----------+-------------------------------------+         | 0         | Reserved (not to be assigned)       |         |           |                                     |         | 16-255    | Unassigned (IETF Review)            |         |           |                                     |         | 256-8175  | Reserved (No assignments)           |         |           |                                     |         | 8176-8183 | Experimentation (No assignments)    |         |           |                                     |         | 8184-8190 | Vendor Private Use (No assignments) |         |           |                                     |         | 8191      | Reserved (not to be assigned)       |         +-----------+-------------------------------------+                Figure 7.  OSPFv3 LSA Function Codes   o  The assignment policy for OSPFv3 LSA function codes in the range      16-255 has changed and are now assigned subject to IETF Review.      New values are assigned through RFCs that have been shepherded      through the IESG as AD-Sponsored or IETF WG documents      [IANA-GUIDE].Lindem, et al.               Standards Track                   [Page 10]

RFC 7770               OSPF Capability Extensions          February 2016   o  OSPFv3 LSA function codes in the range 8176-8183 are for      experimental use; these will not be registered with IANA and MUST      NOT be mentioned by RFCs.   o  OSPFv3 LSAs with an LSA Function Code in the Vendor Private Use      range 8184-8190 MUST include the Enterprise Code [ENTERPRISE-CODE]      as the first 4 octets following the 20 octets of LSA header.   o  If a new LSA Function Code is documented, the documentation MUST      include the valid combinations of the U, S2, and S1 bits for the      LSA.  It SHOULD also describe how the Link State ID is to be      assigned.5.3.  OSPF RI LSA TLV Type Assignment   [RFC4970] created the registry for "OSPF Router Information (RI)   TLVs".  IANA has updated the reference for this registry to point to   this RFC.  References within that registry to [RFC4970] have been   updated to point to this RFC; references to other RFCs are unchanged.   The definition and assignment policy has been updated as follows.   The registry is now comprised of the fields Value, TLV Name, and   Reference.  Values 3-9 have already been assigned.  Value 1 has been   assigned to the Router Informational Capabilities TLV and value 2 has   been assigned to the Router Functional Capabilities TLV as defined   herein.            +-------------+-----------------------------------+            | Range       | Assignment Policy                 |            +-------------+-----------------------------------+            | 0           | Reserved (not to be assigned)     |            |             |                                   |            | 10-32767    | Unassigned (IETF Review)          |            |             |                                   |            | 32768-32777 | Experimentation (No assignments)  |            |             |                                   |            | 32778-65535 | Reserved (Not to be assigned)     |            +-------------+-----------------------------------+                         Figure 8.  OSPF RI TLVs   o  Types in the range 10-32767 are to be assigned subject to IETF      Review.  New values are assigned through RFCs that have been      shepherded through the IESG as AD-Sponsored or IETF WG documents      [IANA-GUIDE].Lindem, et al.               Standards Track                   [Page 11]

RFC 7770               OSPF Capability Extensions          February 2016   o  Types in the range 32778-65535 are reserved and 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 cover the range being assigned.5.4.  Registry for OSPF Router Informational Capability Bits   [RFC4970] created the registry for "OSPF Router Informational   Capability Bits".  IANA has updated the reference for this registry   to point to this RFC.  The definition and assignment policy has been   updated as follows.   o  This registry is now comprised of the fields Bit Number,      Capability Name, and Reference.   o  The values are defined inSection 2.6.  All Router Informational      Capability TLV additions are to be assigned through IETF Review      [IANA-GUIDE].5.5.  Registry for OSPF Router Functional Capability Bits   IANA has created a subregistry for "OSPF Router Functional Capability   Bits" within the "Open Shortest Path First v2 (OSPFv2) Parameters"   registry.  This subregistry is comprised of the fields Bit Number,   Capability Name, and Reference.  Initially, the subregistry will be   empty but will be available for future capabilities.  All Router   Functional Capability TLV additions are to be assigned through IETF   Review [IANA-GUIDE].6.  References6.1.  Normative References   [OPAQUE]  Berger, L., Bryskin, I., Zinin, A., and R. Coltun, "The             OSPF Opaque LSA Option",RFC 5250, DOI 10.17487/RFC5250,             July 2008, <http://www.rfc-editor.org/info/rfc5250>.   [OSPF]    Moy, J., "OSPF Version 2", STD 54,RFC 2328,             DOI 10.17487/RFC2328, April 1998,             <http://www.rfc-editor.org/info/rfc2328>.   [OSPFv3]  Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for             IPv6",RFC 5340, DOI 10.17487/RFC5340, July 2008,             <http://www.rfc-editor.org/info/rfc5340>.Lindem, et al.               Standards Track                   [Page 12]

RFC 7770               OSPF Capability Extensions          February 2016   [RFC-KEYWORDS]             Bradner, S., "Key words for use in RFCs to Indicate             Requirement Levels",BCP 14,RFC 2119,             DOI 10.17487/RFC2119, March 1997,             <http://www.rfc-editor.org/info/rfc2119>.   [RFC4970] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and             S. Shaffer, "Extensions to OSPF for Advertising Optional             Router Capabilities",RFC 4970, DOI 10.17487/RFC4970,             July 2007, <http://www.rfc-editor.org/info/rfc4970>.   [TE]      Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering             (TE) Extensions to OSPF Version 2",RFC 3630,             DOI 10.17487/RFC3630, September 2003,             <http://www.rfc-editor.org/info/rfc3630>.6.2.  Informative References   [ENTERPRISE-CODE]             Eronen, P. and D. Harrington, "Enterprise Number for             Documentation Use",RFC 5612, DOI 10.17487/RFC5612,             August 2009, <http://www.rfc-editor.org/info/rfc5612>.   [EXP-TE]  Srisuresh, P. and P. Joseph, "OSPF-xTE: Experimental             Extension to OSPF for Traffic Engineering",RFC 4973,             DOI 10.17487/RFC4973, July 2007,             <http://www.rfc-editor.org/info/rfc4973>.   [GRACE]   Moy, J., Pillay-Esnault, P., and A. Lindem, "Graceful OSPF             Restart",RFC 3623, DOI 10.17487/RFC3623, November 2003,             <http://www.rfc-editor.org/info/rfc3623>.   [IANA-GUIDE]             Narten, T. and H. Alvestrand, "Guidelines for Writing an             IANA Considerations Section in RFCs",BCP 26,RFC 5226,             DOI 10.17487/RFC5226, May 2008,             <http://www.rfc-editor.org/info/rfc5226>.   [P2PLAN]  Shen, N., Ed., and A. Zinin, Ed., "Point-to-Point Operation             over LAN in Link State Routing Protocols",RFC 5309,             DOI 10.17487/RFC5309, October 2008,             <http://www.rfc-editor.org/info/rfc5309>.   [STUB]    Retana, A., Nguyen, L., Zinin, A., White, R., and D.             McPherson, "OSPF Stub Router Advertisement",RFC 6987,             DOI 10.17487/RFC6987, September 2013,             <http://www.rfc-editor.org/info/rfc6987>.Lindem, et al.               Standards Track                   [Page 13]

RFC 7770               OSPF Capability Extensions          February 2016Acknowledgments   The idea for this work grew out of a conversation with Andrew Partan   and we thank him for his contribution.  The authors thank Peter   Psenak for his review and helpful comments on early draft versions of   the document.   Special thanks to Tom Petch for providing the updated IANA text in   this document.   Comments from Abhay Roy, Vishwas Manral, Vivek Dubey, and Adrian   Farrel have been incorporated into later draft versions of this   document.   Thanks to Yingzhen Qu for acting as document shepherd.   Thanks to Chris Bowers, Alia Atlas, Shraddha Hegde, Dan Romascanu,   and Victor Kuarsingh for review of this document.Lindem, et al.               Standards Track                   [Page 14]

RFC 7770               OSPF Capability Extensions          February 2016Authors' Addresses   Acee Lindem (editor)   Cisco Systems   301 Midenhall Way   Cary, NC  27513   United States   Email: acee@cisco.com   Naiming Shen   Cisco Systems   225 West Tasman Drive   San Jose, CA  95134   United States   Email: naiming@cisco.com   Jean-Philippe Vasseur   Cisco Systems   1414 Massachusetts Avenue   Boxborough, MA  01719   United States   Email: jpv@cisco.com   Rahul Aggarwal   Arktan   Email: raggarwa_1@yahoo.com   Scott Shaffer   Akamai   8 Cambridge Center   Cambridge, MA  02142   United States   Email: sshaffer@akamai.comLindem, et al.               Standards Track                   [Page 15]