Hi Edison

3 floors are unable to communicate====they are connecting to failed Switch.how the STP Will Fails Over====the Whole Switch Down(sup Problem)HSRP In the Picture======the Faild Switch also acts As Primary.how could u help now?

10xs

Ali

Do the 3 floors have connections to the working switch as Edison asked. If not then it won't matter whether you move the STP root for the vlans.

The STP shoudl have failed over for you. How are your floor switches connected to your core switches and how are your core switches connected to each other.

Jon

If the floors are only connecting to the failed switch, then there is nothing STP can do. You need to run connections from the floors to both switches in order to have true redundancy.

Hello

no freinds the 3 floors Doesn't Have connection to the Working CORE.The 2 cores connected 2gather Via L2 Link;the access switches let say 2 access Switches Connected 2gather via Stuck cable and each access Switch has a Link to the core1 and the other ACCESS Switch has Link to the core2.and as i mentioned before every Core its root for Particular Vlans and the 2nd Core also Root for Particular Vlans,any Recomdation ?any Help

10xs

Hi Dear Ali,

The STP will not work until u have redundant connections between all u r switches i.e each access switch should have 2 connections each going to the two core switches.if this present then one of u r link will be in blocking state and one will be in forwarding.If the forwarding link goes down then stp will automatically unblock the blocked link.

Thanks

Mahmood

STP takes care of LAYER2 connectivity. If you have lost your #1, then there is not even Layer 1 connectivity. I.E.: You can imagine that you have only the second c6509.

Now, you said your access switches are connected using STACK cables. Are they c3750 or c3560? That's a big difference, since c3560 don't have stackwise, and technology is more or less like a normal ethernet cable with trunk.

I imagine your topology as following:

c6509-1==XX==c3560-1==c3560-2====c6509-2

XX represents broken connection.

Check the following:

1. #1 may still be up and tell everybody that it's root, and then loose information. Try disconnecting it.

2. Check connection c3560-1==c3560-2. Are trunks enabled there?

3. write "show spanning-tree vlan XX" (in IOS) or "show spantree XX" (in catos), where XX is your user VLAN. Write this command on access switches and see which port is ROOT. All information flows to the port that is marked ROOT.

Hello

the access Switches are 3550;the Stack cable IS a GBIC USB cable...Dont Forget HSRP In Place Also...

10xs

Hi ALi

Can u plz post the topology of u r scenario it will be very helpful to sort out the problem.

Thanks

Mahmood

can you paste configuration of the ports here? Add attachment to message, and add configuration of two of your access switches and the second core switch. Also, paste here "show spanning-tree XX" command results from the swtich that has problems. XX being your user VLAN.

Hello!

check the attachment:

partial config for 2 vlan:

DS1

****

STP vlan 100 priority 4096

STP vlan 200 priority 8192

DS2

***

STP vlan 200 priority 4096

STP vlan 100 priority 8192

********************************

DS1

***

int vlan 100

ip address 100.x.100.3/24

standby 20 ip 100.200.100.1

standby 20 priority 110

standby 20 preempt

int vlan 200

ip address 100.x.200.3/24

standby 21ip 100.200.200.1

DS2

***

int vlan 200

ip address 100.x.200.3/24

standby 21ip 100.200.200.1

standby 21 priority 110

standby 21 preempt

int vlan 100

ip address 100.x.100.2/24

standby 20 ip 100.200.100.1

10xs for ur time

Ali

Ali,

When the primary core switch is down can you capture/post the output of 'show spanning-tree vlan (#)' from one of those access switches. The access switch should see the secondary core switch as the root for the VLAN at this point. I assume the uplink ports between the switches are already configured as trunk ports.

HTH

Sundar

Hello Sundar!

the secondary Core acts as a root pimary for Particular Vlans as the Digrame implies also the Config..when the 2nd Core Down 3 Floors stop working and STP DIDN'T Fails over

Ali

On the access switch any one of those three floors connecting to can you issue the command 'show spanning-tree vlan (affected_vlan_#)' and post the output here. This would help us troubleshoot why STP didn't failover.

HTH

Sundar