RE: Autorp Listener. I don't get the point....

Hi,

The idea behind autorp listener is that it permits you to configure only
"sparse-mode" on the interface, yet still distribute the autorp groups in
dense mode. This predates the no dm-fallback solution.

If you have no RP configured, then I think you will find that your (*,G)
entries for these groups have the "D" flag at the end of the first line,
indicating these groups are being distributed in dense mode.

As it happens, the autorp groups CAN be distributed in sparse mode, for
example by configuring a static RP for these groups. But this is not
usually considered a practical solution to RP redundancy, failover or
automatic advertisement.

HTH,

Bob Sinclair CCIE 10427

> -----Original Message-----
> From: nobody_at_groupstudy.com [mailto:nobody_at_groupstudy.com] On Behalf Of
> groupstudy_at_nyms.net
> Sent: Tuesday, March 09, 2010 10:50 AM
> To: ccielab_at_groupstudy.com
> Subject: Autorp Listener. I don't get the point....
>
> I am confused over the autorp listener command. Now before you comment,
> I *know* that it enabled 224.0.1.39/40 to run in dense mode. However
> this is what I don't get.
>
> Dense mode - floods all traffic out interfaces and waits for prunes if
> required.
>
> Sparse mode - sender unicasts then mcasts traffic to the RP (it must
> know about before). If receiving traffic, then it must know about RP to
> send joins to the RP.
>
> So with that in mind, people say that auto-rp kind of needs dense mode
> and won't work on pure sparse-mode setup. However, if I have 2 routers
> connected, both running sparse mode only, and both doing send-rp-
> announce to claim themselves as candidate RPs, then I see both routers
> have eachothers Routerx,224.0.1.39 paths in the mroute table. So if
> this was truly sparse mode behavior, how do they have eachothers
> announcements?
>
> Secondly, I have labbed and found I can have SW2----R5----R4. All
> running sparse mode only, R5 send-rp-announce and SW2 send-rp-
> discovery. I look at R4 and it has the RP mappings! How does it receive
> this if everything is supposedly running in sparse?
>
> So I hear people say about using the autorp-listener command, but I
> can't find out EXACTLY what it does. It doesn't seem to affect a
> routers ability to actually listen to auto-rp messages, am I right in
> thinking it's actual role is to FLOOD the received messages from one
> interface to another?
>
>
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Received on Tue Mar 09 2010 - 11:40:44 ART