All things related to multicast

[Stig Venaas <>]

David Farmer wrote:
> On 25 May 2006 Matthew Davy wrote:
>
>
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> > I believe that should be 0.0.0.0/8 *not* 0.0.0.0/0 :)
> >
> > My personal opinion is that all the IANA reserved space should be  
> > filtered (eg 235/8, 236/8, etc) at domain borders.    However, when I  
> > suggested this at a Joint Tech's a few years ago, several people were  
> > quite opposed to this.     Passing 236/8 interdomain is no different  
> > than passing 10/8, both are IANA reserved addresses and, IMO,  
> > everyone should be filtering these at domain borders.
>
>
> I've made similar suggestions and had similar reactions in the past.  But I've 
> made the suggestion more recently and with the worms sweeping through 
> Multicast and hosing MSDP several times in the past couple years, I'd say 
> some have warmed to the idea.  I'd like to propose we block the IANA 
> Reserved Multicast Space.  Would it be possible for you to do some work 
> and collect dtata to see if there is any sings of use, other than worms? 

In general I wouldn't recommend blocking reserved space. It makes it 
very hard for some of the space to become un-reserved in the future if 
you see what I mean. If at some point some of this space should be 
unblocked, it might be hard to get everyone to open up.

Of course as an administrator I might want to block it, knowing that I 
would be able to unblock my routers if necessary...

Stig

> > The other point you made regarding rate-limiting is a good one as  
> > well.   We already do per-peer SA limiting.    We also have the  
> > ability to do per-source SA limiting.    There was a thread on this  
> > list a while back about implementing some per-source SA limits.    My  
> > opinion is that limiting each source IP to some relatively large  
> > number of different groups (say 1,000) on the backbone is a good  
> > thing for the overall stability of multicast and wouldn't hinder any  
> > legitimate use of multicast.    But, again, I think the consensus  
> > that last time this was discussed was that the backbone shouldn't do  
> > that type of limiting.    Is that still the consensus ?
>
>
> I'd support doing the rate limiting, again maybe some data would help with 
> the argument.
>
>
> > Also, in terms of Bill's and Cisco's lists being out of date, I'm  
> > sure they are.    However, I think it's the most complete list out  
> > there today.   If there are other groups that should be added, we'll  
> > certainly consider adding them.
> >
> > - - Matt
> >
> >
> > On May 25, 2006, at 12:40 PM, John Kristoff wrote:
> >
> >
> > > On Thu, 25 May 2006 12:11:16 -0400
> > > Matthew Davy 
> > > <>
> > >  wrote:
> > >
> > >
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> > > > NEW ABILENE MSDP FILTER
> > > >
> > > >   sources:
> > > >     (0.0.0.0/0,*)          Link Local Addresses
> > >
> > > Do you mean 0.0.0.0/32 or perhaps even the entire reserved block of
> > > 0.0.0.0/8?
> > >
> > > Bill's draft and Cisco list are not so up to date considering the
> > > multicast swamp gets polluted quicker than anyone would like and I
> > > am not actively maintaining the page I started for hardening anymore.
> > > It sort of depends on where your priorities are for filtering.  If
> > > you want to cut down on bogus MSDPs, clearly filtering the reserved
> > > /8's are going to make a much bigger difference than the control
> > > plan overlapping /24's, but if you want be conservative then maybe
> > > focus on rate limiting strategies to minimize state and flooding
> > > explosion?
> > >
> > > John
> >
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