6509 CatOS with 75% CPU usage

Unanswered Question
Aug 9th, 2007

What could be causing the following output?

I am at a complete loss....

CPU utilization for five seconds: 77.26%

one minute: 78.00%

five minutes: 78.00%

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

--- ----------- ---------- -------- ------- ------- ------- --- ---------------

1 0 3114019818 0 22.74% 22.00% 22.00% -2 Kernel and Idle

12 862269979 2879430535 88000 3.88% 3.00% 3.00% -2 IDLE_Tasks

70 274629044 502897995 487000 1.88% 1.00% 1.00% 0 SptBpduRx

71 682466690 406248844 42000 55.92% 55.00% 55.00% 0 SptBpduTx

91 820338232 2743826908 56000 5.72% 5.00% 5.00% -2 SptFlush

176 40705 84 43000 0.06% 0.92% 0.98% 910112916 telnet176

189 789810246 2120581445 348000 4.28% 4.00% 4.00% -2 SlcpProcess

I have this problem too.
0 votes
  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
wochanda Thu, 08/09/2007 - 10:23

SptBpduTx is the process responsible for sending spanning-tree BPDU's. I cant tell from this output why this is happening, but if I had to guess i'd say you have a trunk link flapping, causing lots of TCN's to be forwarded out.

Look at 'show logging buffer 1023' to see if you have any flapping ports. If so, troubleshoot them. If not, pick a port participating in spanning-tree and do a:

Switch> (enable) show spantree stat 1/1 3

Port 1/1 VLAN 3

SpanningTree enabled for vlan = 3

Vlan based information & statistics

spanningtree type ieee

spanningtree multicast address 01-80-c2-00-00-00

bridge ID priority 32771

(bridge priority: 32768, sys ID ext: 3)

bridge mac address 00-16-9c-da-46-40

bridge hello time 2 sec

bridge forward delay 15(15) sec

topology change initiator: 1/0

topology change FALSE

topology change time 35

topology change detected FALSE

topology change count 0

topology change last recvd. from 00-00-00-00-00-00

For the command, pick a port and a VLAN carried on the port (pick you're most utilized VLAN). Here, look for # of topology changes. If it is large, and increasing quickly, this is likely the problem. Use the 'topology change last recvd from' to track it down to the switch that has the flapping port.

javickas1 Fri, 08/10/2007 - 06:24

Thanks for the advice, I will let you know what the problem was.

javickas1 Fri, 08/10/2007 - 07:37

OK the advice you gave was on mark. I did have some issues with TCNs however, this is not the root cause of the issue. Brief description of Topology. About 150 VLANs 90% carried over trunk ports to Access layer switches.

Here is the last output: note the excessive BPDU transmits:

Please note the last TCN I initiated by changed dup and speed of a connected switch.

sh spantree stat 5/1 1

Port 5/1 VLAN 1

SpanningTree enabled for vlan = 1

BPDU-related parameters

port spanning tree enabled

state forwarding

port_id 0x2201

port number 0x201

path cost 4

message age (port/VLAN) 14(20)

designated_root 00-00-cd-04-89-d0

designated_cost 19

designated_bridge 00-17-df-e0-6c-00

designated_port 0x2201

top_change_ack FALSE

config_pending FALSE

port_inconsistency none

PORT based information & statistics

config bpdu's xmitted (port/VLAN) 9146047(118845)

config bpdu's received (port/VLAN) 9(1008)

tcn bpdu's xmitted (port/VLAN) 1(14)

tcn bpdu's received (port/VLAN) 279(6)

forward trans count 5

scp failure count 0

root inc trans count (port/VLAN) 0(0)

inhibit loopguard FALSE

loop inc trans count (port/VLAN) 0(0)

Status of Port Timers

forward delay timer INACTIVE

forward delay timer value 15

message age timer INACTIVE

message age timer value 14

topology change timer INACTIVE

topology change timer value 35

hold timer INACTIVE

hold timer value 1

delay root port timer INACTIVE

delay root port timer value 0

delay root port timer restarted is FALSE

Vlan based information & statistics

spanningtree type ieee

spanningtree multicast address 01-80-c2-00-00-00

bridge priority 32768

bridge mac address 00-17-df-e0-6c-00

bridge hello time 2 sec

bridge forward delay 15(15) sec

topology change initiator: 4/46

last topology change occured: Fri Aug 10 2007, 10:13:11

topology change FALSE

topology change time 35

topology change detected FALSE

topology change count 9

topology change last recvd. from 00-03-6b-63-e2-01

adrian.jg.harris Fri, 08/10/2007 - 04:43

How many vlans do you have defined ?

How many trunk ports are these vlans distributed through ?

Use SHOW TRUNK to compare the configured vlans with the in use vlans for each trunk port.

If you prune the trunk ports to only carry the vlans actually in use you may drastically reduce the CPU workload.

You will then need to manage the trunk ports more thoroughly as it can be confusing if a vlan doesn't work on an edge switch because it is blocked from the core trunk port.

Adrian.

Actions

This Discussion