[c-nsp] 6500 & broadcast-storm control

[Saku Ytti]

On (2009-07-21 09:33 +0100), Phil Mayers wrote:

Hey,

> Obviously one thing to look at is broadcast storm control on the
> 6500s. However, from what I can make it it's rather primitive; the
> rate of broadcast traffic is capped only in 1-second windows and
> doesn't take account of packet-size? Does anyone have any experience
> of it? Does it work well.

storm-control works just fine. But unfortunately for WS-X6704-10GE minimum
amount of 0.34% which is too much for the box to handle without starting to
flap BGP/LDP/IS-IS etc.

Even if you could limit them to acceptable level, you'll still be looping
unknown unicast, unless you've explicitly stopped forwarding them (which
implies you must have only 1 switch or you've synchronized ARP timeout with
MAC timeout).

> Is it more subtle, and the SP is being overwhelmed by the punt? We
> run CoPP but obviously that's layer3. I don't have any layer2 MLS
> rate-limiters enabled, and since they're per-box rather than
> per-port I doubt they'd help.

My guess would be this also, that you simply overloaded the SUP. Maybe if
you can recreate it in controlled environment, you could see what the
software is doing and maybe even find way to protect yourself.

-- 
  ++ytti