HSRP and Spanning-tree on Edge switch

wasanmesetthee · ‎07-26-2010

Hi There,

i have 2 of Cisco 4948 that i make it as Core switch called Core1 and Core2 and also have 2 of Cisco 2960 act as edge switch called edge1 and edge2. my edge switch are connected to both core switch by trunk Core1 -> edge1 and Core2 -> edge2 , on between both edge switch there also connected on Trunk .

on Core switch i have configure on each vlan as HSRP by the Core 1 is higher priority. Actually all the traffic from both edge should go through Core1 as the Primary unit but my problem is traffic from edge1 go through Core1 and traffic from edge2 go through Core2 ; attached are my config on all those device.

connection of my Edge :

Edge 1 : Gi0/1 -> Core 1 : Gi1/8 # Trunk

Edge 1 : Gi0/2 -> Edge 2 : Gi0/1 # Trunk

Edge 2 : Gi0/1 -> Edge 1 : Gi0/2 # Trunk

Edge 2 : Gi0/2 -> Core 2 : Gi1/8 # Trunk

What i can do to make all traffic through only 1 Core for both of my edge switch on the HSRP environment ? Need you expert.

Thanks,

Jon Marshall · ‎07-26-2010

Have you set the STP priority for the vlans on the core switches ie. set core 1 to be STP root and core 2 to be STP secondry.

Also a better setup would be to connect each edge switch to both cores rather than connect the edge switches together.

Jon

wasanmesetthee · ‎07-26-2010

Hello,

yes i did that on both Core

Core 1

spanning-tree vlan 10-11,20-21,30-31,40-41,50,60-61,70,80,100 priority 24576

Core 2

spanning-tree vlan 10-11,20-21,30-31,40-41,50,60-61,70,80,100 priority 28672

if i maintain the current structure can i do something on Spanning Tree on Edge switch ? as i saw the Gi0/1 Altn BLK 4 on Edge 2 , not sure if this is the cause of traffic can not go through Core 1 Via Edge 1 .

BTW as i would prefer to remain current structure is due to the cabling and space to wiring that we have limited.

Many Thanks,

Jon Marshall · ‎07-26-2010

If you want to keep the same topology then you can look to modify the STP priority or STP port cost so that the blocked port becomes the one between edge2 and core2. See the config docs for details -

http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.2/50sg/configuration/guide/spantree.html#wp1036887

Jon