All things related to multicast

[Stig Venaas <>]

Bill Owens wrote:
> On Tue, Jul 15, 2008 at 02:03:46PM -0400, Michael Lambert wrote:
> > Hello All,
> >
> > We are finally planning to bite the bullet and bring up multicast  
> > connectivity to both Internet2 and NLR.  We have separate border  
> > routers plus a core router.  Do we need to do anything more with the  
> > three routers than 1) make sure we have fully-meshed iBGP peering  
> > (IPv4 multicast NLRI) and 2) configure all three routers in an MSDP  
> > mesh group?  Just to keep things amusing, we're running JUNOS, IOS and  
> > IOS-XR.
>
> The only thing I can think of to watch out for is the difference in the way that IOS and JUNOS can be configured to do RPF checks. By default IOS will use multicast routes if it has them, but will also accept unicast. I don't know whether that can be changed. 
>
> JUNOS will do whatever you tell it to do, but I believe that the cookbook 
> config only uses multicast routes, and that's the way that I2 has it set up. 
> I had an email conversation a couple of weeks ago with Lenny Giuliano where 
> he cleared up for me that it can be configured to be the same as Cisco, 
> though I don't know whether that's actually the right way to do it ;)

Yes, I believe JUNOS can do whatever you want. I would suggest using
only multicast routes for RPF though. Note that for IPv6, IOS uses only
multicast routes (although there is a way to change it on some versions).

Even if your own routers don't need the multicast routes for RPF, you
may be peering with someone that needs them...

Stig

> Bill.