All things related to multicast

["Michael H. Lambert" <>]

All,

I'm probably just demonstrating my cluelessness, but a session we are trying
to announce isn't making it to Abilene and I can't figure out why.

Topology (PIM SM [or Sparse/Dense] on all interfaces):

   +-------+                 +-------+                  +--------+
   |Abilene|  BGP UC+MC NLRI |GigaPoP|  Static mroutes  |Internal|
   | Core  |<--------------->|Border |<---------------->| Campus |
   |Router |      MSDP       |Router |       MSDP       | Router |
   +-------+                 +-------+                  +--------+

Note:  The "Internal Campus Router" is not our campus unicast border routers
(which are a pair of UNIX boxes running GateD and screend).

The multicast boundary and SA filter access lists are at least close to the
BCP.

A host inside our campus is announcing a session.  On our internal router, I
see (from "show ip mroute 224.2.127.254"):

(128.182.61.51, 224.2.127.254), 00:04:04/00:00:01, flags: CLTA
  Incoming interface: GigabitEthernet5/0/0.1, RPF nbr 0.0.0.0
  Outgoing interface list:
    ATM0/0.2, Forward/Sparse-Dense, 00:04:04/00:03:25
    GigabitEthernet5/0/0.7, Forward/Sparse-Dense, 00:04:04/00:02:54

My understanding of the flags is that "A" means that this (S,G) (and any
session announcements in it) is being announced via MSDP.

Now, on our GigaPoP border router:

(128.182.61.51, 224.2.127.254), 00:31:58/00:02:19, flags: CLMT
  Incoming interface: ATM5/0/0.2, RPF nbr 192.88.115.130, Mroute
  Outgoing interface list:
    ATM5/0/0.4, Forward/Sparse-Dense, 00:31:10/00:02:35
    ATM5/0/0.6, Forward/Sparse-Dense, 00:31:11/00:03:04
    Loopback0, Forward/Sparse-Dense, 00:31:58/00:02:51
    ATM5/0/0.3, Forward/Sparse-Dense, 00:31:58/00:02:55

The "M" flag suggests that this router is hearing the (S,G) via MSDP, but I
take it that the lack of an "A" flag means it is not being announced.  The
RPF neighbor is correct.  In fact, if I do a "show ip rpf 128.182.61.51" on
the Abilene core router (CLEV), I get the expected result.  (None of the
outgoing interfaces is the Abilene interface.)

My understanding is that nobody in the outside world can see our session
announcement unless (128.182.61.51, 224.2.127.254) is announced to Abilene
by our border router.

I'm at a loss as to how to track this one down.  Can anyone offer any
suggestions?

Michael

+-------------------------------------------------------------------------+
| Michael H. Lambert, Network Engineer             Phone: +1 412 268-4960 |
| Pittsburgh Supercomputing Center                 FAX:   +1 412 268-8200 |
| 4400 Fifth Avenue, Pittsburgh, PA  15213         

        |
+-------------------------------------------------------------------------+