Current Meeting Report

2.5.8 UniDirectional Link Routing (udlr)

NOTE: This charter is a snapshot of the 54th IETF Meeting in Yokohama, Japan. It may now be out-of-date.

Last Modifield: 06/24/2002

Emmanuel Duros <>
Hidetaka Izumiyama <>
Routing Area Director(s):
Bill Fenner <>
Alex Zinin <>
Routing Area Advisor:
Bill Fenner <>
Mailing Lists:
General Discussion:
To Subscribe:
Description of Working Group:
Note: An alternate site for UDLR's files is:

The UDLR working group issued the RFC 3077 in March 2001. This RFC describes a link-layer tunneling mechanism (LLTM) for supporting unidirectional links (UDL) in the Internet.

During the design of this mechanism by the UDLR working group, several implementations evolved. These implementations are fully interoperable and are currently being used in several operational environments.

As of the publication of RFC 3077, the working group has decided to further their work by issuing the following objectives:

1. Produce informational rfc's that describe in detail the requirements of example case study scenarios as listed below. Note that these scenarios relate to field experiments that are being undertaken based on the LLTM mechanism:

a) configuration of multicast routing protocols over a unidirectional link

b) configuration of unicast routing protocols over a unidirectional link

c) securing operation of a UDLR network

2. Identify security holes

3. Push the current document (RFC 3077) status to Draft Standard.

Goals and Milestones:
DEC 01  Submit I-D on the configuration of multicast routing protocols over a UDL
DEC 01  Submit I-D on the configuration of unicast routing protocols over a UDL
DEC 01  Submit I-D on securing operation of a UDLR network
MAR 02  Submit the Link Layer Tunneling Mechanism to the IESG for consideration as a Draft Standard
JUL 02  Submit Internet-drafts as Informational RFCs
  • - draft-ietf-udlr-dvmrp-conf-03.txt
  • - draft-ietf-udlr-multicast-issues-00.txt
  • Request For Comments:
    RFC3077 PS A Link Layer Tunneling Mechanism for Unidirectional Links

    Current Meeting Report

    IETF-54 UDLR WG minutes

    Here is the minutes of UDLR WG.


    16th July, 13:00 - 13:45 at Room 501
    Attendee 24 person

    * WG update(Izu) 5min

    * I-D update : draft-ietf-udlr-dvmrp-conf-03.txt
    (Substituted by Izu)

    * PIM-SM over UDLR(Husni) 15min

    Advice from Dave Thaler
    In case of tie break of metric, it is one solution to advertise longer prefix of
    RP or host route of RP.

    Question from Tony
    What happen more than one UDL?
    Solution-1 : split into two PIM-SM domain.
    Solution-2 : use different multicast group for each UDL, and put separate RP for
    each UDL.
    Solution-3 : use MSDP

    * Discussion
    If general document status too slow, how about to split multicast issue from
    general document ?
    ---> No objection. Decide on the mailing list.

    Hidetaka Izumiyama / JSAT


    Configuration of DVMRP over a UDL
    PIM-SM over UDLR