Same STP ROOT ID for 2 Vlans

begnatoff · ‎03-06-2003

I have 2 - 6513 along with 4 cat4003's trunked together. STP has assigned the same root id to 2 of the vlans. I am assuming it is because I have a LD430 bridging VLAN3 int0 and VLAN8 int1. VLAN8 int1 is a small server farm that resides on the same physical switch as VLAN3 int0.

With the 2 VLANS having the same root id, STP is blocking the vlans at different locations within its tree. Performing a sh cam VLAN8 on the 4003 lists MAC addresses for VLAN8 and VLAN3. I am currently routing the Vlans via a pair of 7507's. I plan on moving those connections to the 6513 soon. Do you think I will have problems when I migrate my router connections over to the 6513's with port flapping because the MAC addresses of the servers residing on both VLAN networks? I think I have a lot of options, Pruning vlans, creating secure ports on LD430 (I really don't want to do this), yada,yada,yada. What do you think is the best config for me?

Here is the sh spanning-tree from the 6513'sfor the 2 vlans with the same root ID.

VLAN0003

Spanning tree enabled protocol ieee

Root ID Priority 32768

Address 0004.4dc4.cc02

Cost 12

Port 835 (Port-channel3)

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

Bridge ID Priority 32768

Address 000b.60ad.a383

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

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

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

Po1 Altn BLK 12 128.833 P2p

Po2 Desg FWD 12 128.834 P2p

Po3 Root FWD 12 128.835 P2p

Po10 Desg FWD 12 128.836 P2p

VLAN0008

Spanning tree enabled protocol ieee

Root ID Priority 32768

Address 0004.4dc4.cc02

Cost 67

Port 833 (Port-channel1)

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

Bridge ID Priority 32768

Address 000b.60ad.a388

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

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

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

Po1 Root FWD 12 128.833 P2p

Po2 Desg FWD 12 128.834 P2p

Po3 Altn BLK 12 128.835 P2p

Po10 Altn BLK 12 128.836 P2p

smahbub · ‎03-17-2003

Depending on number of switches you have, just follow some fashion

to divide vlans ; and assign some switch as root for each vlan.

I don't think so migration should be a problem.

I feel that creating secure prots on LD 430 is better.