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New Member

3524 PWR XL gigabitethernet drops

I'm a begginer.

I have a 3524 PWR XL that's logging "gibabitethernet0/2 down and up" errors. I changed the GBIC on both the sides(3524 and 6509), but no luck. The PC's get dropped more often than the phones. We have a data and voice vlan on each switch. The switch,pc's, and phones are all set to auto sense. The log server dosen't show any dropped fastethernet port connections just the gibabitethernet0/2 port. We've had bad GBIC's before and that solved are problem then, but not this time. I guessing the blade on the 6509 that the switch is on might be bad, because we have other switches on that blade that act up in the same way, but not as often. This happens approx 4 to 6 times a day. I'm pretty sure that the IOS version on all the switches are the same. and the configuration files are the same.....excep of course for vlan defenitions.

How would I go about troubleshooting this.......

Any help would be appreciated........


Re: 3524 PWR XL gigabitethernet drops

Check for any duplex mismatch at both ends. You could set them to auto.

New Member

Re: 3524 PWR XL gigabitethernet drops

Are you talking about a duplex mismatch between the 3524 switch and the 6509 switch?

New Member

Re: 3524 PWR XL gigabitethernet drops

Chris, are you using both Gig ports on the 3524 for redundancy between two distribution switches (6509s)?

It sounds like there may be spanning tree updates that could be causing a root cost change and switching blocking/forwarding states.

If so, you may want to issue the "show spanning-tree brief" on the 3524 and "show spantree statistics MOD/PORT VLAN" on the 6509 (if using CatOS, I haven't used a 6509 yet) to verify which Gig is forwarding and which is blocking.

You can check the port ID information. On the example below, 3524 show it as decimal and the 4006 as hexadecimal.

So, Gig0/1 on the 3524 is going to port ID 128.132 and the 3/4 port ID is 0x8084 (dropping the 0x). Converting the 80 hex = 128 dec and 84 hex = 132 dec.

Also, if using spanning-tree priority, check to make sure both distribution switches don't have the same priority.

Hope this helps and doesn't send you on a goose chase.

If anyoneone else has observations jump in!

Good luck,


::: 3524 :::


Spanning tree enabled protocol IEEE

ROOT ID Priority 32768

Address 0005.d7bb.1d00

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Bridge ID Priority 49152

Address 0004.320b.1080

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Port Designated

Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Gi0/1 128.40 128 3004 FWD 0 0005.d7bb.1d00 128.132

Gi0/2 128.48 128 3004 BLK 3004 0004.320b.1080 128.48

::: 4006 :::

Port 3/4 VLAN 410

SpanningTree enabled for vlan = 410

BPDU-related parameters

port spanning tree enabled

state forwarding

port_id 0x8084

port number 0x84

path cost 4

message age (port/VLAN) 0(20)

designated_root 00-05-d7-bb-1e-99

designated_cost 0

designated_bridge 00-05-d7-bb-1e-99

designated_port 0x8084

top_change_ack FALSE

config_pending FALSE

port_inconsistency none

New Member

Re: 3524 PWR XL gigabitethernet drops

I think this problem is nothing to do with configuration. The system has been running for a year without a problem. Nothing has changed to this point.....I positive. The problems were are having i'm sure are due to a bad switch, port on the 6509 module port , or the module(blade) itself. I would I troubleshoot a hardware problem like this. I now have the problem on 4 switches, before it was only 1, but two are on on blade and 2 are on the other.

I've opend a TAC case, but I'm just being asked to changed DTP settings and It hasn't solved the problem.

The drops are for a split second and then the connection is restored.

No, we are not using both gbic ports, but I'm considering doing so now.

Any links you recomend?


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