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Network Working Group Internet Architecture Board Request for Comments: 1370 Lyman Chapin, Chair

                                                            October 1992

                  Applicability Statement for OSPF

Status of this Memo

 This memo is an IAB standards track Applicability Statement for the
 Internet community, and requests discussion and suggestions for
 improvements.  Please refer to the current edition of the "IAB
 Official Protocol Standards" for the standardization state and status
 of this specification.  Distribution of this memo is unlimited.

1. INTRODUCTION

 Users and vendors have expressed a strong need for IP routers from
 different vendors that can interoperate using a common Interior
 Gateway Protocol (IGP).  There is therefore an urgent requirement for
 a high-functionality non-proprietary 'open' IGP that will be
 ubiquitously available from all IP router vendors.

 The Open Shortest Path First (OSPF) routing protocol [1] was
 developed by the IETF to fill this need.  This Applicability
 Statement specifies the circumstances under which OSPF must be
 implemented by router vendors.  The history of OSPF development and
 the reasoning behind this Applicability Statement will be found in
 [5].

 This Applicability Statement places a requirement on vendors claiming
 conformance to this standard, in order to assure that users will have
 the option of deploying OSPF when they need a multivendor,
 interoperable IGP in their environment.  Users are of course free to
 use whatever routing protocol best meets their requirements.

2. APPLICABILITY OF OSPF

 An IP router that implements any routing protocol (other than static
 routes) is required to implement OSPF [1] and the OSPF MIB [2].
 Within OSPF, implementation of all features except TOS (Type-of-
 Service) routing is required; implementation of TOS routing is
 recommended.

 This requirement does not prevent a router from implementing other
 routing protocols in addition to OSPF.  Complete and definitive
 requirements on all aspects of an IP router will be found in a
 forthcoming Applicability Statement: "Requirements for IP Routers"

IAB [Page 1]  RFC 1370 Applicability Statement: OSPF October 1992

 [4], currently in preparation in the IETF.  "Requirements for IP
 Routers", when it becomes a Standard, will take precedence if its
 requirements for OSPF should conflict with this present RFC.

 It should be noted that OSPF is intended for use by routers for
 exchanging dynamic routing information, and not for use by hosts.  As
 discussed in Section 3.3.1.4 of STD-2, "Requirements for Internet
 Hosts -- Communication Layers" [3], 'wiretapping' of routing
 protocols by hosts is not recommended.  Recommended mechanisms for a
 host to use for discovering local routers and detecting dead routers
 will be found in [3].  In particular, the ICMP Router Discovery
 messages, under development, will provide a standard way for a host
 to learn the addresses of local routers [6].

3. REFERENCES

 [1] Moy, J., "OSPF Version 2", RFC 1247, Proteon, Inc., July 1991.

 [2] Baker, F., and R. Coltun, "OSPF Version 2 Management Information
     Base", RFC 1253, ACC, Computer Science Center, August 1991.

 [3] Braden, R., Editor, "Requirements for Internet Hosts --
     Communication Layers", IETF, STD 3, RFC 1122, October 1989.

 [4] Almquist, P., Editor, "Requirements for IP Routers", Work in
     Preparation, IETF.

 [5] Gross, P., Editor, "Choosing a "Common IGP" for the IP Internet
     (The IESG's Recommendation to the IAB)", RFC 1371, IESG, October
     1992.

 [6] Deering, S., Editor, "ICMP Router Discovery Messages", RFC 1256,
     Xerox PARC, September 1991.

Security Considerations

 Security issues are not discussed in this memo.

Author's Address

 A. Lyman Chapin
 BBN Communications Corporation
 150 Cambridge Park Drive
 Cambridge, MA  02140

 Phone: 617-873-3133
 Fax:   617-873-4086
 Email: Lyman@BBN.COM

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