[c-nsp] Interdomain Multicast Routing

[Paul Cosgrove]

Hi Mike,

Normally MSDP will work with just unicast BGP, but then RPF check
changed between IOS and IOS XR...

In IOS a router performing an RPF check looks first at the multicast
routing table, and if it doesn't find a match it then looks at the
unicast table.

In IOS XR if you have any routes in the multicast table, and you do not
find the one you are looking for, RPF fails.  Doesn't matter whether or
not the prefix is in the unicast table.

You may have a situation where you are given multicast feeds (e.g. IPTV)
and are only supplied with multicast BGP routes because they do not want
any of your unicast traffic.  You may well wish to receive those feeds,
and also receive multicasts from sources which only advertises unicast
routes.  If I understand the RPF correctly, this presents you with a
problem and may have to look at statics/ACLs etc.

Paul.


Mike Louis wrote:
> This has been a  confusing subject for me. If you enabled msdp between 2 pim sm domains and enabled mc routing on the intermediate bgp routers while using normal non-mbgp routing wouldn't mc still work? Why would you want to use mbgp unless you wanted mc routes to take a different path than unicast routes? Do most sp these days support mc in their networks for customers?
> 
> Thanks
> 
> mike
> 
> -----Original Message-----
> From: Jeff Tantsura <jeff.nsp at gmail.com>
> Sent: Monday, September 01, 2008 4:53 AM
> To: 'Muarwi' <muarwi at gmail.com>; cisco-nsp at puck.nether.net <cisco-nsp at puck.nether.net>
> Subject: Re: [c-nsp] Interdomain Multicast Routing
> 
> 
> Hi,
> 
> The combination you've described has been working for many years,
> very well tested, supported by all major vendors.
> PIM (bidir as well) is used for intradomain  multicast routing independently
> of interdomain multicast (MSDP/MBGP).
> Cisco does support PIM Bidir
> 
> Cheers,
> Jeff
> 
> P.S. Best book ever - "Interdomain Mutlicast Routing" by
> Edwards/Giuliano/Wright
> 
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-
>> bounces at puck.nether.net] On Behalf Of Muarwi
>> Sent: maandag 1 september 2008 9:49
>> To: cisco-nsp at puck.nether.net
>> Subject: [c-nsp] Interdomain Multicast Routing
>>
>> Hi guys, I'm sorry if my questions is rather out of cisco's things.
>>
>> I've read books about interdomain multicast routing (also one from cisco
>> press). From what I get, the solutions offered is PIM SM - MBGP - MSDP.
>>
>> My questions is :
>> 1. what about using PIM Bidir for interdomain multicast? Is it possible to
>> implement it in Cisco?
>> 2. Has BGMP been being implemented in vendors?
>>
>> Thanks a lot for your response
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