[c-nsp] Microsoft NLB vs Cisco

[Peter Rathlev]

On Sat, 2008-05-10 at 12:09 -0400, Tim Durack wrote:
> Anyone using Microsoft NLB Multicast mode for a cluster?
>
> It requires a static arp entry on Cisco, as the cluster ip resolves to
> a multicast mac, which can't/shouldn't be learned via arp.

I find that a very irritating requirement of the MS NLB. :-)

> So we do something like: "arp a.b.c.d 0100.5e7f.xxyy arpa"
> Apparently this results in software switching the adjacency on a
> Sup720, which is painful to say the least.
> 
> Any suggestions?

I guess you're referring to CSCee49121 "static ARPs dont create adjs
when used with routes pointing at intf". I thought this was only a
problem if you used it like this:

ip route 10.11.12.13 255.255.255.255 Gi1/1
arp 10.11.12.13 030b.adc0.ffee Gi1/1

Is the problem also there without the route statement? We use it against
two MS NLBs, and we don't see any problems. The traffic doesn't seem to
be software switched, but apart from consulting Feature Manager and
looking at the CPU interrupt usage, I'm not completely sure how to check
it. How do you do it?

Regards,
Peter