HSRP/VRRP on same switch-stack

[j.schouwenburg]

Hello, I have got a question regarding configuring HSRP only on one switch stack. The L1 configuration is as follows:

     _____   _____

    | SW1 |-| SW2 |

    |_____|-|_____|

       |       |

     __|__   __|__

    |     |-|     |

    | SW3 | | SW4 |

    |_____|-|_____|

SW1 & SW2 are my switches (3750E) and form a stack (the drawn links are stack cables).

SW3 & SW4 are independend customer switches (Avaya) and are physically connected with ethernet cables

Chalange:

I need to deliver a redundante connections to the LAN. The customer already deliveres the L2 lan between SW3 and SW4 and uses VRRP.

I see three options:

1: Configure both ports on SW1&2 as access-ports into a vlan and just configure an IP address on it

I am than in fact relying on spanning tree SPT to handle the L2 loop I just created. Not bad, but not desireable. It would also mean the customer should configure the STP port priorities else the wrong link might end-up being blocked.

     _____________

    | SW1     SW2 |

    |      I      |

    | -+---+---+- |

    |__|_______|__|

       |       |

     __|__   __|__

    |  |  | |  |  |

    | -+--|-|--+- |

    |  P  | |  S  |

    | SW3 | | SW4 |

    |_____| |_____|

2: Configure both ports on SW1&2 as routed ports and configure both in the same HSRP/VRRP group

This would mean running HSRP on one logical box. My main question is: is this a supported and working configuration ? Are there any major drawbacks. According to the manual there is an indication that says HSRP can be used on "two or more routers", but can we use just one?

     ______ ______

    | SW1  |  SW2 |

    |__P___|___S__|

       |       |

     __|__   __|__

    |  |  | |  |  |

    | -+--|-|--+- |

    |  P  | |  S  |

    | SW3 | | SW4 |

    |_____| |_____|

3: Configure both links on SW1&2 as a member of a multi-chassis etherchannel

Unfortunately this is no option because SW 3&4 consist of individual switches.

Any ideas on this topic? I think option 2 would be the cleanest if supported) solution as this would not mean any reconfiguring on the customer site.

[Joseph W. Doherty · Accepted solution]

Disclaimer

The      Author of this posting offers the information contained within this      posting without consideration and with the reader's understanding   that    there's no implied or expressed suitability or fitness for any    purpose.   Information provided is for informational purposes only  and   should not   be construed as rendering professional advice of any  kind.   Usage of  this  posting's information is solely at reader's own  risk.

Liability Disclaimer

In      no event shall Author be liable for any damages whatsoever    (including,   without limitation, damages for loss of use, data or    profit) arising  out  of the use or inability to use the posting's    information even if  Author  has been advised of the possibility of   such  damage.

Posting

#2, yes you can run HSRP on a single 3750 stack.  Unsure about VRRP, but suspect it too would work.

"Any ideas . . ."  How about instead of cross connecting SW3 and SW4, run dual link from each to SW1 and SW2 and Etherchannel them?