From: ccie2be (ccie2be@nyc.rr.com)
Date: Thu Aug 12 2004 - 19:58:58 GMT-3
Thanks, Scott.
I understood what and how an ip mroute command worked, but I was concerned
about one mroute overriding another mroute. What I failed to realize
initially was that the source address for each mroute would be different for
the situation where the answer to both of your questions was no.
But, upon closer examination, this makes complete sense since in that case
the ip address of the source will be different than the ip address of the
rp.
Although this situation is highly unlikely in a real production network, I
can easily imagine something as contrived as this being in the real lab.
Thanks for helping me see this. Tim
----- Original Message -----
From: "Scott Morris" <swm@emanon.com>
To: "'ccie2be'" <ccie2be@nyc.rr.com>; "'Group Study'"
<ccielab@groupstudy.com>
Sent: Thursday, August 12, 2004 5:57 PM
Subject: RE: mroute issue
> If the SPT utilizes a different path, the question becomes:
>
> Is the new receiving interface either 1) the unicast reverse path
interface
> or 2) the previously enabled ip mroute path?
>
> If the answer is no to both parts, then you'll need a new mroute.
>
> See, the problem is that this is a misunderstood command. This is NOT any
> sort of static route, or anything manipulating the flow of traffic
directly.
> It is a list of allowed overrides for the standard RPF check (or a list of
> OR values in the receiving interface) specifically for multicast packets.
>
> HTH,
>
>
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
> JNCIP, et al.
> IPExpert CCIE Program Manager
> IPExpert Sr. Technical Instructor
> swm@emanon.com/smorris@ipexpert.net
> http://www.ipexpert.net
>
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> ccie2be
> Sent: Thursday, August 12, 2004 4:15 PM
> To: Group Study
> Subject: mroute issue
>
> Hi guys,
>
> Here's the scenario:
>
> Sparse mode is running in portions of the network. Not all interfaces and
> routers are multicast enabled.
>
> Because of this, on a paricular router, the rpf check to the rp fails. An
ip
> mroute fixes that problem.
>
> Now, what happens when that router with the mroute for the rp switches
over
> to the SPT?
>
> If the SPT uses a different interface, will a new rpf check for the source
> now fail?
>
> Can someone explain if there's a potential problem here I need to be aware
> of ? And, if so, what I should do about this?
>
> TIA. Tim
>
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