Fwd: MSTP and dot1q-tunnel

From: Daniel Valle (danielfrvalle@gmail.com)
Date: Mon Mar 31 2008 - 20:53:53 ART


Gents,
I found the issue. there were 2 issues indeed. First I forgot to set the
dot1q-tunnel ( :-S ) .. Second. And that I didn't know... the end switches
were running ISL trunks. When I changed that to Dot1q trunks, I got it
working fine.... I thought i'd work evenif it was ISL.... on the Edge
routers...anyway... it's working now..

---------- Forwarded message ----------
From: Daniel Valle <danielfrvalle@gmail.com>
Date: Mon, Mar 31, 2008 at 5:53 PM
Subject: MSTP and dot1q-tunnel
To: groupstudy <ccielab@groupstudy.com>

Hi GS,

does MultipleSTP and do1q tunnels compatible ? I made a trunk between SW1
and SW3 via SW4, and configured SW4 with do1q tunnel. All 6 interfaces
between them have the following config:
(SW4)
interface FastEthernet0/X
 switchport access vlan 100
 switchport mode access
 l2protocol-tunnel cdp
 l2protocol-tunnel stp
 l2protocol-tunnel vtp
 l2protocol-tunnel point-to-point pagp
 l2protocol-tunnel point-to-point lacp
 l2protocol-tunnel point-to-point udld
 no cdp enable
!

Sw1 is the Root and SW3 should reach SW1 via PO14 ( po from SW3 , through
dot1q-tunnel in SW4 and then reaching SW1) .No matter what I do , the PO14
in SW3 keeps in Designated port. if I make the same config beween the direct
links between SW1 and SW3 they work fine,

 Rack3SW3#show spanning-tree mst 2

##### MST2 vlans mapped: 2-100
Bridge address 0019.aab4.fe00 priority 32770 (32768 sysid 2)
Root address 0019.aa6f.4f00 priority 24578 (24576 sysid 2)
              port Po23 cost 68660 rem hops 18

Interface Role Sts Cost Prio.Nbr Type
---------------- ---- --- --------- --------
--------------------------------
Po14 Desg FWD 1 128.176 P2p
Po23 Root FWD 66660 128.248 P2p
!
this is the config for SW1 and SW3

SW3
 !
interface Port-channel14
 switchport trunk encapsulation isl
 switchport mode trunk
 spanning-tree mst 1 cost 1
 spanning-tree mst 2 cost 1
end
!
!
SW1
!
 !
interface Port-channel14
 switchport trunk encapsulation isl
 switchport mode trunk
 spanning-tree mst 1-2 port-priority 0
!

Any Ideas are welcome!



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