All things related to multicast

[David Farmer <>]

On 1/4/13 08:56 , Bill Owens wrote:
> On Fri, Jan 04, 2013 at 08:32:50AM -0600, David Farmer wrote:
> > NLR's leak hit us bad, we have R&E in our global route table and the
> > Commodity Internet in a VRF.  NLR leaking 300K+ routes to us and into
> > our R&E table blew our TCAMs out.  Weren't set of for 700K+ IPv4 routes,
> > we are not though.  Implemented a plan reallocation of TCAM this morning
> > in the heat of battle.
>
> We still haven't had a confirmation of where the leak originated, but I2 
> seems to be blaming NLR as well. . .
>
> > We've set a max prefix on NLR of 20K routes and will be doing the same
> > for I2 and all our other R&E peers in a future maintenance window
>
> Us too; I hate to do that since max prefix is so heavy-handed. But losing the 
> I2 connections beats the hell out of having the entire network fall over!
>
> > Bill, the first leak was at 08:20UTC ish when were the other leak(s) you
> > saw, I'm trying to correlate stuff.
>
> All of our backbone routers started complaining about TCAM at 08:21:46 or 
> :47, but we saw other log messages 10-20 seconds earlier that might have been 
> related: customer mBGP sessions dropping and PIM errors, which is what made 
> me think that this was multicast at first.
>
> We don't graph BGP prefixes (yet!) but one of our members does, and I've 
> attached his graphs from this morning. That's the only evidence I have that 
> the leak happened twice; by the time of the second leak our routers were 
> already busy screaming at us about TCAM exhaustion and lost BGP sessions, so 
> it's difficult to tell from the logs.

Thanks for the graph

We had been planning to reallocated our TCAM to the following this morning.

>sh mls cef max
FIB TCAM maximum routes :
=======================
Current :-
-------
 IPv4 + MPLS         - 768k (default)
 IPv6                - 120k
 IP Multicast        - 8k

That is accomplished with;

mls cef maximum-routes ipv6 120
mls cef maximum-routes ip-multicast 8

We did it that way because I wanted IPv4 and MPLS in a TCAM common pool. 
If you do;

mls cef maximum-routes ipv4 768

You get IPv4 and MPLS in separate pools.  We hadn't implement the change 
before this morning mostly because we got busy doing other things, but 
was sure I really only wanted only 8k multicast routes, but we are only 
seeing a 1000 to 2000 multicast routes these days so it would probably 
be fine.

Later

--
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David Farmer               Email: 

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