Double Connection

[Rafael Mendes]

Hello Everyone,

My question is related with double connection in switches.

I have one switch connected to other two switches, and i would keep the two active connections, like bellow:

          SWITCH1

           |          |

           |          |

SWITCH 2    SWITCH3

How can I keep the two connections without the spanning tree block one?

Ps: I need maintain layer 2 connections.

Tks a lot.

Rafael

[cpembleton]

Rafael,

Since S2 and S3 aren't connected STP won't block any ports.

Even if they where and S1 was the root is would block link between S2<>S3 and both links to S1 would stay active.

HTH.

Chad

[John Blakley]

As Chad said, there's no loop in the configuration that you have so STP won't block any ports.

HTH,

John

Please rate all useful posts...

[Rafael Mendes]

Sorry, i have a connection with S2 and S3.

              SWITCH1

               |            |

               |            |

    SWITCH 2---SWITCH3

                        |

                SERVERS

The STP cannot block the S2->S3 Link, it is my communication witch  STP-MST and for my servers connected in two switches(i dont have high availability connection for servers).

How i can maintain the two connections without  block S2-S3 link? Some feature like a FabricPath?

* S2 and S3 are my cores switches

Tks

[cpembleton]

Fabricpath is only avaliable with the Nexus Platform.  What type of switches are these?

Not sure I understand.  Are you trying to dual-home servers to S2 and S3?  Or just trying to keep all the ISL's forwarding?  For what reason?

If S2<>S3 link is blocked you still have a path end to end via S1.  Or you could change the STP port priority so that say S1<>S3 link gets blocked and all traffic will flow from S3>S2>S1.

HTH

Chad

[Rafael Mendes]

S2 and S3 are 6509, S1 is a 3750.

I dont have servers in dual-home, each server have only one cable connected to a 6509(S2 or S3).

The connection for S2->S1 is a 1GB lan-to-lan link, the connection for S3-S1 is a 100MB Lan-to-lan Link, the connection for S2 and S3 is a 10GBEthernet Link in my lan, therefore it cannot stay in blocked state.

I would like to maintain the two links, (S2-S1)1GB and (S3-S1)100MB in forward state,

without blocking S2-S3(10GB) connection, its possible?

[cpembleton]

Say S1 is your root bridge.  The link that would be blocked by default is S1<>S3 since the cost would be higher compared to a 10g and 1g link combined cost.  That would be the prefered path and shouldn't casue you any issues. 

But one has to be blocked or your create a loop. 

If your worried about overloading the S1<>S2 link you could add more links and turn it into an etherchannel.  

HTH.

Chad

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