From: Edwards, Andrew M (andrew.m.edwards@boeing.com)
Date: Fri Nov 04 2005 - 22:11:51 GMT-3
If they're congruent then there would be no issue for spt failover on
the leaf router.
The main issues are this:
Did you pass the RPF to the BSR/AUTORP mapper?
Did you pass the RPF towards the RP?
Did you pass the RPF towards the source of (S,G) for the default SPT
failover?
As indicated, SPT failover is the default behavior for a router in
sparse mode.
So, it will build a SPT to the source NOT the RP by default.
What does this mean? It means we spent a lot of time setting up the
routers to pass the RPF check for the RP in order to get your first
response to a test packet on the group. However, once you send data to
the group, the leaf (end routers) will by default change from using the
RP to the SPT and potentially stop receiving (symptomatically we see
them stop responding) to the test data.
This can be a problem is the route to the Source for the group is out a
different interface than where you are receiving it from. IOW, you
failed the RPF check and stop passing data because the paths to RP and
Source (S,G) are not congruent.
This can happen on NBMA topologies where there is a known route towards
a source that is NOT directly connected (e.g. its reachable via another
spoke on hub and spoke frame cloud at L2, but at L3 looks like its
directly attached).
Andy
-----Original Message-----
From: Balogh, Jim [mailto:jim.balogh@gwl.com]
Sent: Friday, November 04, 2005 4:43 PM
To: Chris Lewis; kevin gannon; ccielab@groupstudy.com
Subject: RE: Sparse mode multicast ?
Not sure....good question! Anyone know?
Jim
________________________________
From: Chris Lewis [mailto:chrlewiscsco@yahoo.com]
Sent: Friday, November 04, 2005 5:29 PM
To: Balogh, Jim; kevin gannon; ccielab@groupstudy.com
Subject: RE: Sparse mode multicast ?
what if the shared tree and source tree are congruent?
Chris
"Balogh, Jim" <jim.balogh@gwl.com> wrote:
Kevin,
Just gave the scenario a quick glance, and you need the ip pim
spt-threshold command on the last-hop router....in this case R2.
The switch from shared to source tree (with Sparse Mode) happens
upon
the arrival of the first data packet at the last hop router.
This switch
occurs because the ip pim spt-threshold interface configuration
command
controls that timing, and its default setting is 0 kbps.
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
Behalf Of
kevin gannon
Sent: Wednesday, November 02, 2005 12:12 PM
To: ccielab@groupstudy.com
Subject: Re: Sparse mode multicast ?
Anyone any ideas ?
Regards
Kevin
On 11/1/05, kevin gannon wrote:
> Have a simple set with three routers
>
> R2--------R5(RP)--------R3
>
> Its running all sparse mode. R2 has an igmp join statement for
> 225.25.25.25 and R3 is sending a ping to this group source
from
> 35.35.35.3. Below is the mroutes I see on R3 the source of the
stream.
> I am experimenting with set the spt threshold to infinity on
R3 below
> is the different mroute
> outputs:
>
> Default setup no SPT threshold changed
> ####################################################
> (*, 225.25.25.25), 00:36:46/stopped, RP 5.5.5.5, flags: SJPCL
> Incoming interface: Serial0/1, RPF nbr 35.35.35.5
> Outgoing interface list: Null
>
> (35.35.35.3, 225.25.25.25), 00:05:20/00:02:59, flags: PLT
> Incoming interface: Serial0/1, RPF nbr 0.0.0.0, Registering
> Outgoing interface list: Null
>
> (*, 224.0.1.40), 00:37:22/stopped, RP 5.5.5.5, flags: SJPCL
> Incoming interface: Serial0/1, RPF nbr 35.35.35.5
> Outgoing interface list: Null
>
> SPT Threshold set to infinity
> ###################################################
>
> (*, 225.25.25.25), 00:40:15/stopped, RP 5.5.5.5, flags: SPCL
> Incoming interface: Serial0/1, RPF nbr 35.35.35.5
> Outgoing interface list: Null
>
> (35.35.35.3, 225.25.25.25), 00:08:49/00:02:58, flags: PLT
> Incoming interface: Serial0/1, RPF nbr 0.0.0.0, Registering
> Outgoing interface list: Null
>
> (*, 224.0.1.40), 00:40:51/stopped, RP 5.5.5.5, flags: SPCL
> Incoming interface: Serial0/1, RPF nbr 35.35.35.5
> Outgoing interface list: Null
>
> My questions:
> 1. Why do I not see any outgoing interfaces in either output
> for (35.35.35.3, 225.25.25.25),
>
> 2. In the default SPT setup how come I see the "Registering"
> going on and on and on.....
>
>
> Thanks & Regards
> Kevin
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