spanning-tree topology changes

[D@1984]

hi,

on my root switch when I run #show spanning-tree vlan 20 details, I get the below:

Number of topology changes 5020 last change occurred 03:45:37 ago
from GigabitEthernet1/0/22

But when I try to see what is connected to GigabitEthernet1/0/22 by doing show mac-address table or show cdp neighbors, there is no output, the interface status shows that it's connected though. I don't have physical access to the site. Is there any other command I can use to see what port is connected too?

I have a quite high cpu utilisation on my switch and the number of topology changes seems to be quite high,  I'm trying to find out whats going on.

Thanks

[balaji.bandi]

You need to post below output what causing the issue.

give us more information :

1. what is the device model

2. what IOS running

3. post show process cpu sorted | ex 0.00

Some device may have malfunctioning so we dont get MAC address, if you think that is the port you suspect and shutdown the port- rather whole network collapse for some reason. and see if that improves.

than leave for while, ask some one onsite and visit and see what is the device and take action, is this required to be in the network or can be removed.

[D@1984]

C3750, Version 12.2

#show process cpu sorted | ex 0.00
CPU utilization for five seconds: 48%/4%; one minute: 21%; five minutes: 17%
PID Runtime(ms) Invoked uSecs 5Sec 1Min 5Min TTY Process
12 295979753 272135788 1087 25.01% 3.23% 1.58% 0 ARP Input
3 1756 1241 1414 2.11% 0.16% 0.05% 1 SSH Process
224 134303278 229104125 586 1.62% 0.78% 0.66% 0 IP Input
82 341667113 1722950210 198 1.46% 1.26% 1.26% 0 Fifo Error Detec
162 315361716 1267235341 248 1.13% 0.76% 0.78% 0 Hulc LED Process
97 94347572 322492448 292 0.97% 0.18% 0.16% 0 HRPC hlfm reques
238 221013496 284778382 776 0.81% 0.61% 0.61% 0 Spanning Tree
123 355005220 69882058 5080 0.81% 1.00% 1.02% 0 hpm counter proc
76 162722213 854847736 190 0.64% 0.42% 0.42% 0 RedEarth Tx Mana
119 75572855 444017082 170 0.48% 0.18% 0.18% 0 hpm main process

[balaji.bandi]

We need to have full version - post-show version - as per 12.2 is too old and have some bug, we can only confirm once we see the full version.

ARP Input - is taking CPU as per your output, it all depends - 48% for the time posted as not high as expected.

what is the outcome after the port shutdown?

[D@1984]

I haven't shut the port yet, will try it on Monday

#show version
Cisco IOS Software, C3750 Software (C3750-IPSERVICESK9-M), Version 12.2(58)SE2, RELEASE SOFTWARE (fc1)
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 1986-2011 by Cisco Systems, Inc.

ROM: Bootstrap program is C3750 boot loader
BOOTLDR: C3750 Boot Loader (C3750-HBOOT-M) Version 12.2(44r)SE8, RELEASE SOFTWARE (fc1)

uptime is 1 yeares
System returned to ROM by power-on
System restarted at 
System image file is "flash:c3750-ipservicesk9-mz.122-58.SE2.bin"

cisco WS-C3750G-48PS (PowerPC405) processor (revision L0) with 131072K bytes of memory.

Last reset from power-on
8 Virtual Ethernet interfaces
156 Gigabit Ethernet interfaces
The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.
B
Motherboard revision number : A0
Model number : WS-C3750G-48PS-S

Version ID : V08

Switch Ports Model SW Version SW Image
------ ----- ----- ---------- ----------
1 52 WS-C3750G-
2 52 WS-C3750G-
* 3 52 WS-C3750G-

Switch 01
---------
Switch Uptime : 1 year, 

Model revision number : H0
Motherboard revision number : A0

Version ID : V06

Switch 02
---------
Switch Uptime : 1 year

[balaji.bandi]

Let us know the outcome once you shutdown the port is this stable or you still have issues.

i would suggest upgrading to the latest stable - 122-55.SE12 and test it.

one thing we missed here, is this causing issue only if that port connected, and you never had any issue before?

[D@1984]

the port was connected to a server, so I configured portfast and bpduguard on it. I don't see mac address flapping any more on the switch. I still dont know why I couldn't see the mac address. 

[balaji.bandi]

if it is connected to esxi, esxi has internal vswitch. glad all working as expected. so we close this ticket now.