Cisco 4506 L3 Switch Failover

[CT2NCMike]

Hi All,

I have an interesting situation that I'd like to get some opinions on.

Here is a diagram:

                   ______________(FIREWALL)_______(INTERNET)

                   |

                   |

    [Cisco 4506 L3 Switch]---------[Cisco 3550 Switch]----(demarc)----M.A.N.----(demarc)----[Cisco 3550 Switch]---------[Cisco 4506 L3 Switch]

If the MAN has problems and goes down, the 4506 on each side doesn't know it because it still sees the interface on the 3550 switch as being up and up. 

I want to set it up so that the 4506 on the left will constantly send a string of pings to the other 4506 and if it doesn't receive a response then it will shut down the interface connected to the 3550 switch.

I can't think of a way to do this so any ideas would be greatly appreciated.

Thanks in advance!

Mike H

CCNA  

[Jon Marshall]

Mike

It depends on whether the 4500 switches are L2 adjacent or not ie. you have 3550 switches in between, are these merely acting as L2 devices ?

If you want to shut an interface down depending on ping failure then EEM might be the best solution. If so then you should repost this into the Network Management forum where Joe Clarke will probably answer.

If it is a routed connection between the 2 4500 switches then rather than shut an interface you could remove a route, in which case IP SLA could be used in we should able to help.

So best to confirm how connectivity works. Also bear in mind that EEM and IP SLA support will be dependant on supervisor/IOS version you are running.

Jon

[CT2NCMike]

Jon,

Thanks for your response.  The 4506's are acting as L3 switches.  The 3550's are merely L2 devices.  So given that info, would you recommend IP SLA or EEM?

Thanks

Mike

[Jon Marshall]

Mike

If that means the connection between the 4500 switches is L2 only, ie. there is a common subnet at both ends then i think EEM would be the way to go.

Jon