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New Member

6509 sup720 high cpu

I have a pair of 6509's each having a single sup720-3bxl, 6408 8port gbic, and 2 6748 modules. I am experiencing higher than expected interrupt cpu usage with about 900mbps of inbound ip traffic. I don't have dynamic routing, just a few routed vlans and a couple static routes. I am also doing hsrp for the vlan interfaces between the two. Here's some stats:

show proc cpu | exclude 0.00 :

CPU utilization for five seconds: 40%/39%; one minute: 43%; five minutes: 44%

PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process

122 72629332 359004276 202 0.87% 0.64% 0.67% 0 IP Input

show mls stat :

Statistics for Earl in Module 5

L2 Forwarding Engine

Total packets Switched : 561152787313

L3 Forwarding Engine

Total packets L3 Switched : 559997750297 @ 179965 pps

Total Packets Bridged : 345312572741

Total Packets FIB Switched : 213554111543

Total Packets ACL Routed : 0

Total Packets Netflow Switched : 346020241

Total Mcast Packets Switched/Routed : 49412512

Total ip packets with TOS changed : 2

Total ip packets with COS changed : 2

Total non ip packets COS changed : 0

Total packets dropped by ACL : 1215

Total packets dropped by Policing : 0

Total packets exceeding CIR : 0

Total packets exceeding PIR : 0


MAC/IP length inconsistencies : 0

Short IP packets received : 0

IP header checksum errors : 0

TTL failures : 4711

MTU failures : 0

Total packets L3 Switched by all Modules: 559997750297 @ 179965 pps

show plat hard cap cpu :

CPU Resources

CPU utilization: Module 5 seconds 1 minute 5 minutes

3 1% / 0% 0% 0%

4 0% / 0% 0% 0%

5 RP 50% / 49% 46% 45%

5 SP 7% / 0% 5% 5%

Processor memory: Module Bytes: Total Used %Used

3 219980576 53867208 24%

4 219980576 53867448 24%

5 RP 928258080 72475552 8%

5 SP 902888420 144729544 16%

I/O memory: Module Bytes: Total Used %Used

5 RP 67108864 11891816 18%

5 SP 67108864 11891760 18%

I have no ip redirects, no ip unreach, and no ip proxy-arp on these vlan interfaces.

About 90% of the traffic generated is coming in via vlan500 (gige to our bw provider). Most of the traffic than flows to vlan503 (external ip's).

Any suggestions?

New Member

Re: 6509 sup720 high cpu

I've attached my show int switching as well

New Member

Re: 6509 sup720 high cpu

Whoops, forgot to mention I am running 12.2(18)SXF7.

New Member

Re: 6509 sup720 high cpu

Can anyone offer some insight here? Its a bit shocking that a sup720 chokes on less than a gigabit of traffic. I have very little configured on this pair, and I plan to add alot more traffic.

New Member

Re: 6509 sup720 high cpu

Unfortunately more info is going to be needed to lend any real help.

I agree that the CPU usage is a bit on the high side. The usual problems are spanning tree, multicast, ip unreachables, etc...

If possible take a sniffer trace of the incoming traffic to see if you notice anything out of the ordinary. Posting your config may lead to someone noticing something out of the ordinary...

New Member

Re: 6509 sup720 high cpu

Ok. I am attaching a config of router01. I am going to do a packet sniff of inbound traffic as well.

Cisco Employee

Re: 6509 sup720 high cpu

Lets see the following information:

1. show ip traffic (x3 over the course of a min)

2. show proc cpu (while CPU is high)

3. show stack

Lets start with that and we can talk about getting a backplane sniffer capture after I look at the above information.

Email me directly at



Cisco Employee

Re: 6509 sup720 high cpu

Also let me see the following command as well:

1. sh ip nat stat

2. sh ip nat tr verbose

3. show platform hardware pfc mode

4. show mls netflow ip count



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