[c-nsp] Sup720, multicast bothers the CPU
Peter Rathlev
peter at rathlev.dk
Fri Mar 25 06:00:01 EDT 2011
On Wed, 2011-03-23 at 20:55 +0100, Peter Rathlev wrote:
> Thanks. We'll try just adding "ip igmp snooping querier" to the specific
> SVI to see if this in itself would be enough. Next up we try "ip pim
> sparse-mode" on the SVI and "ip multicast-routing" in global.
>
> I'll keep the list updated on how it went. :-)
We now tried both adding an IGMP Querier and enabling multicast-routing
and PIM. None of these things stopped the multicast traffic from hitting
the CPU.
I'm a little puzzled that we actually saw _some_ sources:
xxx#sh ip igmp membership
[...]
*,239.255.255.253 10.26.46.78 00:02:41 02:46 2A Vl46
*,239.255.255.250 10.26.46.77 00:02:43 02:46 2A Vl46
*,224.0.1.40 10.26.46.254 00:02:43 02:53 2LA Vl46
xxx#
Just not from the "interesting" groups. We tried restarting both a
receiver and a source to see if anything changed, and we never saw joins
or "*,<something>".
So a few questions more:
1) Could "offset != 0" somehow mean that the flows cannot be hardware
switched at all? Every single packet has offset != 0, i.e. no packet
observed with offset == 0. We were looking at both an RP SPAN
session and a SPAN session covering the VLAN in question.
2) Could 224.0.0.0/24, which they use for this purpose though that's
wrong, somehow be treated specially by a Sup720? Any chance it would
help using 239.255.255.0/24 instead?
Thanks in advance.
--
Peter
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