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multicast hogging 4507R?

Mark Graham
Level 1
Level 1

i tried a stab and multicasting a FOG image to 4 machines the other day, and i had experienced odd and strange issues.

here is what i encountered:

100% cpu usage on our core switch

core4507#sh processes cpu hist

    9999999999999999999999999999999999999999999999999999999999

    7777888888888877777888888888888887777788888888888888888887

100 **********************************************************

90 **********************************************************

80 **********************************************************

70 **********************************************************

60 **********************************************************

50 **********************************************************

40 **********************************************************

30 **********************************************************

20 **********************************************************

10 **********************************************************

   0....5....1....1....2....2....3....3....4....4....5....5....

             0    5    0    5    0    5    0    5    0    5   

               CPU% per second (last 60 seconds)

the Vlan is in sparse mode

pinging the SVI on the core and or pinging on the core to other devices resulted in MAJOR latencies, packet loss due to the cpu usage, etc....

no other network operations were affected, i could communicate with the rest of the network, and under 1-2ms latencies.

i noticed it due to my opsview server flagging the core as down (SNMP OID's wouldnt return a value) 

it lasted the whole time i was multicasting, i kept a close eye on it.  i highly considered canceling my job, but everything ran smooth. 

when i looked at the cpu sorted history i saw 2 processes, IP Input, and cat4k mgmnt hipri 

is there something that could cause this?  nothing that was multicasting was on the core itself. 

1 Reply 1

InayathUlla Sharieff
Cisco Employee
Cisco Employee

Hi Mark,

Here is the link for troubleshooting high cpu on 4500 switches:

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00804cef15.shtml

Kindly go through the same and update me if you need any clarificiation.

HTH

Regards

Inayath

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