determining path to root

carl_townshend · ‎04-02-2007

Hi all, can anyone help me, I have 2 main switches, the whole lan is just using vlan 1 at the moment, How can i get some switches to use the uplink to 1 of the core switches and some of them to the other, would I just change the port cost or priority ?

Amit Singh · ‎04-02-2007

Hello Carl,

You are looking for PVST load-balancing on the switches. The way to achieve is to dedicate 2 switches in your network and make one as primary root bridge for some vlans and secondry for some and vice-versa on the other switch. For example, Make Switch A is root bridge for Even number of vlans 2,4,6 ... and Switch B as root bridge for ODD vlans like 1,3,5,7....

Please see the link below for undersatnding the same:

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12235se/scg/swstp.htm#wp1039614

HTH,Please rate if it does.

-amit singh

m-haddad · ‎04-02-2007

In order to loadbalance, I suggest to create and etherchannel. Once you create an etherchannel traffic will be balanced and you will get the benifit of double throughput and redundancy.

Hope this helps,

Appreciate your rating,

Regards,

nyr.hakeem-habeeb · ‎04-02-2007

Hi Carl,

Yes, Considering you have only one VLAN, you can only have 1 root i.e. 1 stp instance.

you would have to 'manually' form the desired L2 topology using port cost/priority.

Hope this helps.

Thanks

HH