UniDirectional Link Routing () Charter

NOTE: This charter is accurate as of the 38th IETF Meeting in Memphis, Tennessee. It may now be out-of-date. (Consider this a "snapshot" of the working group from that meeting.) Up-to-date charters for all active working groups can be found elsewhere in this Web server.

Chair(s)

Walid Dabbous <Walid.Dabbous@sophia.inria.fr>
Yongguang Zhang <ygz@isl.hrl.hac.com>

Routing Area Director(s):

Joel Halpern <jhalpern@newbridge.com>

Mailing List Information

General Discussion:udlr@sophia.inria.fr
To Subscribe: udlr-request@sophia.inria.fr
Archive: ftp://zenon.inria.fr/rodeo/udlr/archive.txt

Description of Working Group

Note: An alternate site for UDLR's files is: ftp://irl.cs.ucla.edu/pub/udlr

High bandwidth, unidirectional transmission to low cost, receiver-only hardware is becoming an emerging network fabric, e.g. broadcast satellite links or some cable links.

Two cases for unidirectional links support may be envisaged:

1. unidirectional links on top of bidirectional underlying network (wired Internet) 2. bidirectional islands connected via unidirectional links.

In both cases, the integration of unidirectional links may require changes to the routing protocols in order to preserve dynamic routing across these links. A short term solution (i.e. to solve the first case) is to adopt current protocols with possible modifications. A long term solution (i.e. for the second case) is to propose, design and implement protocols that remove assumed link symmetry (e.g. by supporting 2-way metrics).

There have been several proposed approaches for the short term case. The first is based on the modification of the common routing protocols (RIP, OSPF, DVMRP) in order to support unidirectional links. The second is to add a layer between the network interface and the routing software to emulate bi-directional links through tunnels.

The purpose of the UDLR Working Group, therefore, is to study these approaches and suggest a short term solution to provide dynamic routing (including multicast) in the presence of unidirectional links.

Goals and Milestones

Apr 97: Meet at IETF. Finish discussion of the general solution.
Apr 97: Post the description of the proposed solutions and the issues for the short term solution as I-D(s).
Aug 97: Post the description of the short term solution as an I-D.
Aug 97: Preliminary experiments results of the short term solution.
Dec 97: Produce Informational RFC on the proposed approach.
Dec 97: End WG.