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Spanning Tree Load Balancing

Hello I was reading this link

http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800ae96a.shtml

Trying to understand the Load Balancing Part

I looked to more configurations about this, and I got completely lost.

For Example

F0 | ========= | F0

Catalyst A Catalyst B

F1 | ========= | F1

Suppose now that Switch A is the root for Vlan 5, and Switch B is the root for Vlan 18

Now I want that Vlan 18 uses trunk F0, and that Vlan 5 uses trunk F1

So if I see it in this way (I have no lab equipments so sorry for the post)

For Vlan 5, can I change the priority like this

Switch A -----------------------------------------------------Switch B

F0 Priority 1 | =================== | 1 Priority

F1 Priority 100 | =================== | 100 Priority

And for Vlan 18 can I change the priority like This.

Switch A -----------------------------------------------------Switch B

F0 Priority 100 | =================== | 100 Priority

F1 Priority 1 | =================== | 1 Priority

I know that this cold maybe work (but it’s like a hard thinking) because Switch A owns Vlan 5 and Switch B is the root for vlan 18

Can anyone try to explain this a little bit better?

Thanks

Victor

1 ACCEPTED SOLUTION

Accepted Solutions
New Member

Re: Spanning Tree Load Balancing

Yeah, that can make your head hurt.

First question is, why not just make these two links an etherchannel? If its a channel connection the load is automatically split across both links, and the failover is much faster. This document even suggests that at the end.

If you really do want to do this, realize that you only tune on the 'root' side. If the A switch is your root, do the tuning there. Leave the B switch alone.

Greg

2 REPLIES
New Member

Re: Spanning Tree Load Balancing

Yeah, that can make your head hurt.

First question is, why not just make these two links an etherchannel? If its a channel connection the load is automatically split across both links, and the failover is much faster. This document even suggests that at the end.

If you really do want to do this, realize that you only tune on the 'root' side. If the A switch is your root, do the tuning there. Leave the B switch alone.

Greg

Re: Spanning Tree Load Balancing

hi

in normal stp of two switch network there is one root bridge and other is non root bridge having one designated port and block port to avoid loop. so you will get one designated port on non root bridge throught which u communicat with root bridge so only one link you are using. so when u creat different vlan, it is quite obious all vlan data pass through that one link. If u want to have load balance you have to select two different root bridge and that is what u have done by influancing priority, and by this way u are able to utilise both the link...

devang

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