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"

[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", RFC1247, Proteon, Inc., July 1991.

[2] Baker, F., and R. Coltun, "OSPF Version 2 Management Information
Base", RFC1253, ACC, Computer Science Center, August 1991.

[3] Braden, R., Editor, "Requirements for Internet Hosts --
Communication Layers", IETF, STD 3, RFC1122, 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)", RFC1371, IESG, October
1992.

[6] Deering, S., Editor, "ICMP Router Discovery Messages", RFC1256,
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