cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
417
Views
6
Helpful
4
Replies

CAT 6500 - Two Core Switches - Both Showing HIGH CPU UTILIZATION

astanislaus
Level 2
Level 2

Two Core CAT 6500 switches running CatOS:

=========================================

The CPU Utilization of two CAT 6500 CORE switches are constantly showing over 90% CPU Utilization. The main CPU consumer is always SptBpduRx proces on both CAT 6500.

The customer is not having any impact whatsover in terms of network performance and hence I am ruling out the possibilty of any Spanning Tree Loop. He has had this situtaion for a long time.

I seem to recall that if some sort of Spanning Tree Trace is set on CatOS that this could happen, but I am unable to find any details on this tracing.

Any suggestions on why the CPU utilization is so high, especially the SptBpduRX process and yet there is no impact to any user whatsoever in terms of network performance or connectivity.

4 Replies 4

glen.grant
VIP Alumni
VIP Alumni

You need to look at how it is configured . How many vlans are defined ? Does it have a lot of trunk links ? If so are all unneeded vlans "manually" pruned (not allowed) off all trunk links ? If you do not prune all unneded vlans off your trunks the switch has to keep a instance of spanning tree for all those vlans . That is definitly way too . I'll guarantee it is haveing some effect on customer traffic if its that high . Start checking around , see if the roots for all spanning trees are where they are supposed to be and blocked ports are where you think they should be . Make sure all user ports have portfast turned on if it isn't this causes constant churn of the spanning tree because TCN's are constantly going on and fast aging the cam tables .

vijayasankar
Level 4
Level 4

Hi,

Have you captured any diagnostics output so far. If so, kindly provide the captures for us to understand.

If not,Have a look at this URL to start troubleshooting.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_tech_note09186a00804916e0.shtml#check

Which process is consuming the CPU resource?

-VJ

As I said in my problem description first, it is the SptBpduRX that takes 74% of the 90% CPU utililization.

Hi,

Thanks for the update.

Can you share Any diagnostics captures that you have gathered from those switches.

(Commands like "show spanning-tree vlan x details", show logging etc)

If possible can you provide a network diagram too?

What is the STP protocol that you are running?

802.1d,802.1w or 802.1s?

Kindly revert back to as much information as possible.

-VJ

Getting Started

Find answers to your questions by entering keywords or phrases in the Search bar above. New here? Use these resources to familiarize yourself with the community: