Spanning tree Problem???

Hi All

We have a small Layer 2 network here consisting of various Vlans ( 6 in total)

We have a combination of 6 switches 4 Dell Power connect switches and 2 Cisco 3500 Catalyst switches.

We are running spanning tree across these.

There has been no issues with our NW prior but in the past week the NW simply fails in all VLANs with no indication as to where the problem started.

The symptoms experienced would be loss of packets so when we ping u might get one success
Complete Loss of connectivity in our DMZ and traing VLANs that have no connection to external Vlans.

through a combination of rebooting these switches it will come back up. However it seems to be a different combination each time. Our internal intermapper application is giving no clues.

It points to spanning tree failing and that we have a loop somewhere but I guess I am looking for a troubleshooting starting point. I cannot see it being hardware related but have a spare switch here in any case that could be configured

any advice would be great

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Comments

larkspur

this will help you start (Cisco 3550)

sh spanning-tree
what is the root id? post this info.

provide diagram and the sh spanning-tree info and we should be able to help.

as for Dell, check the dell site for stp settings and troubleshooting commands.

Evertonian

below is the output from the Cisco box in question. I will look to get a diagram to help more wit the topology

14Fitz3524#sh spanning-tree br

VLAN1
Spanning tree enabled protocol IEEE
ROOT ID Priority 0
Address 0011.43f6.f558
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 20
Address 0007.50f0.1f40
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/3 128.15 128 19 FWD 8 0007.50f0.1f40 128.15
Fa0/5 128.17 128 19 FWD 8 0007.50f0.1f40 128.17
Fa0/8 128.20 128 19 FWD 8 0007.50f0.1f40 128.20
Fa0/9 128.22 128 19 FWD 8 0007.50f0.1f40 128.22
Fa0/11 128.24 128 19 BLK 8 0007.50f0.1f40 128.24
Fa0/14 128.27 128 19 FWD 8 0007.50f0.1f40 128.27
Fa0/15 128.28 128 19 FWD 8 0007.50f0.1f40 128.28
Fa0/16 128.29 128 19 FWD 8 0007.50f0.1f40 128.29
Fa0/18 128.32 128 19 FWD 8 0007.50f0.1f40 128.32
Fa0/20 128.34 128 19 BLK 8 0007.50f0.1f40 128.34

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/21 128.35 128 19 BLK 8 0007.50f0.1f40 128.35
Fa0/23 128.37 128 19 FWD 8 0007.50f0.1f40 128.37
Fa0/24 128.38 128 19 BLK 8 0007.50f0.1f40 128.38
Gi0/1 100.40 100 4 FWD 4 0006.5362.4940 100.40
Gi0/2 110.48 110 4 FWD 8 0007.50f0.1f40 110.48

VLAN2
Spanning tree enabled protocol IEEE
ROOT ID Priority 10
Address 0006.5362.4941
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 20
Address 0007.50f0.1f41
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f41 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4941 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f41 128.48

VLAN3
Spanning tree enabled protocol IEEE
ROOT ID Priority 10
Address 0006.5362.4942
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 20
Address 0007.50f0.1f42
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f42 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4942 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f42 128.48

VLAN4
Spanning tree enabled protocol IEEE
ROOT ID Priority 10
Address 0006.5362.4943
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 20
Address 0007.50f0.1f43
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f43 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4943 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f43 128.48

VLAN5
Spanning tree enabled protocol IEEE
ROOT ID Priority 10
Address 0006.5362.4944
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 20
Address 0007.50f0.1f44
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f44 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4944 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f44 128.48

VLAN10
Spanning tree enabled protocol IEEE
ROOT ID Priority 32768
Address 0006.5362.4945
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 32768
Address 0007.50f0.1f45
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f45 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4945 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f45 128.48

VLAN17
Spanning tree enabled protocol IEEE
ROOT ID Priority 32768
Address 0006.5362.4946
Hello Time 2 sec Max Age 20 sec Forward De

Bridge ID Priority 32768
Address 0007.50f0.1f46
Hello Time 2 sec Max Age 20 sec Forward De

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/1 128.13 128 19 FWD 4 0007.50f0.1f46 128.13
Fa0/2 128.14 128 19 FWD 4 0007.50f0.1f46 128.14
Fa0/4 128.16 128 19 FWD 4 0007.50f0.1f46 128.16
Fa0/6 128.18 128 19 FWD 4 0007.50f0.1f46 128.18
Fa0/7 128.19 128 19 BLK 4 0007.50f0.1f46 128.19
Fa0/10 128.23 128 19 FWD 4 0007.50f0.1f46 128.23
Fa0/12 128.25 128 19 FWD 4 0007.50f0.1f46 128.25
Fa0/13 128.26 128 19 BLK 4 0007.50f0.1f46 128.26
Fa0/17 128.31 128 19 FWD 4 0007.50f0.1f46 128.31
Fa0/19 128.33 128 19 FWD 4 0007.50f0.1f46 128.33

Port Designated
Name Port ID Prio Cost Sts Cost Bridge ID Port ID

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

Fa0/22 128.36 128 19 FWD 4 0007.50f0.1f46 128.36
Fa0/24 128.38 128 19 BLK 4 0007.50f0.1f46 128.38
Gi0/1 128.40 128 4 FWD 0 0006.5362.4946 128.40
Gi0/2 128.48 128 4 FWD 4 0007.50f0.1f46 128.48

borumas

Is there any particular switch that you have a hard time telneting to? I had an issue similar to that and it turned out that one switch that I had a hard time getting into used a flakey gbic module. The strange thing about it was that it caused issues on all the other switches on the same vlan until I changed out the gbics, this is probably not your issue but it might be worth considering.

larkspur

The symptoms experienced would be loss of packets so when we ping u might get one success
Complete Loss of connectivity in our DMZ and traing VLANs that have no connection to external Vlans.

Does the issue seem to stay in the direction of your DMZ and traing VLAN's or does it appear across your entire network?

Evertonian

Issue appears accross entire network

We loose connectivity to everything which is weird.

It is as if what ever happens on one switch effects all switches.

Is there a way of getting like an event viewer or anything that shows possible problems or when a NW went down

I am going to run etherreal and see if this picks up anything

Paul Boz

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/comref/d1.htm#wp1064082

The debug spanning-tree commands are extremely useful in diagnosing issues like this. It'd be hard to dedict the loop or misconfiguration without access to your network, so that's the best I can offer.

Evertonian

debug spantree on the catalyst 3500 switch will only give 2 options

Events and Tree

How would i utilise these debug options best?

Thanks again

larkspur

debug spanning-tree event. Displays all spanning tree events, such as changes to the root or to the status of any of the ports.

a syslog server might be helpful in this case.

Evertonian

this is all that happens when i do this

Where do i see the out put?

14Fitz3524#debug s?
snmp spantree standby sw-vlan
14Fitz3524#debug spantree event
Spanning Tree event debugging is on
14Fitz3524#

larkspur

if you are connected to the swicth via vty use
14Fitz3524#term mon
14Fitz3524(config)#logging on
14Fitz3524#sh debug ( to verify)

the debug output will be displayed on your terminal or console session. It will move very quickly so do your best to capture the text.

14Fitz3524(config)#line vty 0 4 ( or whatever you haev set)
logging sync
exec-timout 0 0
do same on console 0

if you are connected to the swicth via console use
14Fitz3524(config)#logging on
14Fitz3524(config)#logging console ( i beleive this is set by default)

or stay connected to the switch and force stp to converge.

best to do during maintenance window of course......