[c-nsp] High CPU on 3750G-24-TS

[Paul Cosgrove]

Hi William,

I would agree with Ozgur that you would be better off loosing the ip 
igmp join-group command.  Also limit the number of register messages 
which can be created per second; it is only needed if you have sources 
attached, but personally I would apply this on every L3 multicast device:
"ip pim register-rate-limit 5"

Have seen a case where register stop messages were lost whilst being 
sent to a 3750.  Debugs on the adjacent device indicated they were all 
being transmitted to the switch, debugs & SPAN on the 3750 indicated the 
switch was receiving very few of these.  

Paul.


William wrote:
> We currently use ip igmp join-group x.x.x.x under the vlan interface.
>
> Cheers.
>
> W
>
> 2008/11/12 Ozgur Guler <gulerozgur at yahoo.co.uk>:
>   
>> As far as i remember ip igmp static-group forces the packets to be process
>> switched on the switch/router. You might need to replace it with ip igmp
>> static-group which will do the same job (put the interface permanently into
>> OIF).
>>
>>
>>
>> --- On Wed, 12/11/08, William <willay at gmail.com> wrote:
>>
>> From: William <willay at gmail.com>
>> Subject: [c-nsp] High CPU on 3750G-24-TS
>> To: "cisco-nsp" <cisco-nsp at puck.nether.net>
>> Date: Wednesday, 12 November, 2008, 11:15 AM
>>
>> Hi List,
>>
>> We currently have a 3750G-E in our network which is experiencing a
>> high CPU load and I'm trying to understand why, the CPU is over 50%
>> all the time and at peak traffic times we are seeing around 85% on
>> Cacti using 5 minute
>>  averages.
>>
>> When running a show proc cpu sorted I can see that IP Input is taking
>> up most of the CPU time with Spanning Tree coming second however ST is
>> only using a fraction of what IP Input is using.
>>
>> The switch is not in a stack, runs IOS version 12.2(25)SEB4 and the
>> image is IPSERVICES, the configuration has one routed port to another
>> site (with sparse-dense-mode on), has one EIGRP process, 19 static
>> routes,  access lists which are only used for SNMP/VTY and it has two
>> VLAN interfaces. One of the VLAN interfaces has sparse-dense-mode
>> enabled and a igmp join-group command. It pushes a lot of multicast
>> traffic (around 10Mbits) which is probably the problem but I thought
>> the 3750 would have been able to handle it without an issue.
>>
>> Any help is appreciated, I'd like to have a good understanding of what
>> is causing the issue.
>>
>> Thank you for your
>>  time,
>>
>> W
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>>
>>     
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