Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Double Connection

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

7 REPLIES
Silver

Double Connection

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

Double Connection

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...

HTH, John *** Please rate all useful posts ***
New Member

Double Connection

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

Silver

Double Connection

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

New Member

Double Connection

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?

Silver

Double Connection

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

Silver

Double Connection

We featured your question on Facbeook. Check out some of the responses here as well: http://www.facebook.com/CiscoSupportCommunity/posts/354427261276179

---

Posted by WebUser Cisco NetPro from Cisco Support Community App

254
Views
0
Helpful
7
Replies
CreatePlease login to create content