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Community Member

Root port

I have two switches A and B connected together through two trunks A1  ---- B1, and A2 ---- B2. present the root bridge is A, and all the ports  are forwarding. As for B, the root port is B1, and B2 in blocking. My  question is how do I make B2 forwaing on B. On my lab I reduced the cost  of B2 on B from 19 to 10, and it works. Bu on cisco site, I was told  you will reduce the cost of A2 on A for B2 to be the root port on B.  Please assist.

5 REPLIES
Silver

Re: Root port

Hi,

You can make it but in that case the B1 will be in blocking. STP has to break the loop somewhere on the non-root bridge.

Check this for further info: http://www.cisco.com/en/US/tech/tk389/tk621/technologies_tech_note09186a00800ae96a.shtml

If you want both in forwarding better to setup an etherchannel.

Hope this helps, rate if does

Krisztian

Community Member

Re: Root port

Kerek,

  Thanks for the reply. What I need is clearification. If I want B1 to be blocked, where will I do the cost manupilation ? on switch A or B. Thats the question.

Cisco Employee

Re: Root port

Hi,

You can either change cost on B or port-priority on A.

HTH,

Lei Tian

Community Member

Re: Root port

Thanks guys, I just lab it, and it worked . You'v just made my day . lol.

Idowu Kehinde

CCNA

CCNP

CCIP

CCIE (written)

On Wed, Apr 21, 2010 at 1:34 PM, letian

Community Member

Re: Root port

How did you manage to pass the IE written (or even CCNP) without knowing  the answer?

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