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New Member

Switches Connectivity Via Transport MUX

Hello,

Is there any provision/command in cisco switches (we are using 4507 L3 switches)... where in case of transport failure between two Muxs (switches are not directly connected to each other, they are connected via transmission MUXs at both end), The connected GIG port on both cisco switches will go down.

Note :- Asking this question as Both the switches are not directly connected , MUX involved in between connectivity... and in our case ports are not going down even there is failure of connectivity between MUXs.

I am looking for a solution, where in case of transport connectivity failure between MUXs, anyhow Switches at both end detect the outage and keep their Gig port auto Shut. So that traffic on that link will shifted to alternate path within seconds

Scenerio attached here for easy understanding.

Regards

11 REPLIES
Gold

Re: Switches Connectivity Via Transport MUX

A few questions.

Who owns the muxes and their respective configurations?

What is the transport between the two Muxes? i.e. Gig/E ?

New Member

Re: Switches Connectivity Via Transport MUX

Hii,

MUXes & their configs are owned & maintained by Services Provider.

Fiber ring between MUXes. In my above question i am querring about Gig port connectivity.

Gold

Re: Switches Connectivity Via Transport MUX

If you route between the two endpoints, a link failure would be recognized by your gig port. Unless there is some way for the provider to drop the link between your switch and the mux based on a failure of the link between the mux.

Bronze

Re: Switches Connectivity Via Transport MUX

Hi,

This one is dead easy - we had the same issue using LES / EES circuits over here.

Create a single-member port-channel with LACP (The Following commands assume the link is a trunk):

interface port-channel 1

switch trunk enc dot

switchport mode trunk

interface GigabitEthernet1/3

descr Po1: MUX Link

switch trunk enc dot

switch mode trunk

channel-group 1 mode active

Do this on both ends of the MUX link - the LACP will bring PO1 down if there is any loss of connectivity.

Hope this helps!

Please rate any useful posts.

Nick

New Member

Re: Switches Connectivity Via Transport MUX

Thanks Nick,

please confirm what this command will do "switch trunk enc dot".

Regards

Bronze

Re: Switches Connectivity Via Transport MUX

switchport trunk encapsulation dot1q

When the port is in trunking mode, the encapsulation used will be 802.1q - instead of ISL

On some devices / IOSs this command isn't needed/accepted because they always use dot1q. If your device doesn't accept the command - then it already uses dot1q.

Nick

New Member

Re: Switches Connectivity Via Transport MUX

Hii Nick,

I guess, we already used this scenerio. But unfortunerly not helping out for our expectation.

Regards

Bronze

Re: Switches Connectivity Via Transport MUX

Hi,

In what way is it not working?

Have you got the port-channel up?

What happens to the port-channel when the MUX goes off?

Nick

New Member

Re: Switches Connectivity Via Transport MUX

Port Channel and respective Gig port always showing UP even in case of failure of transport.

Bronze

Re: Switches Connectivity Via Transport MUX

Hi,

It sounds like you've not got LACP turned on unconditionally.

You need to have:

channel-group 1 mode ACTIVE

if you have anything else, like auto, on or passive this will not work.

The Gig interface will always show as up - only the port channel will go down.

Nick

New Member

Re: Switches Connectivity Via Transport MUX

Hii Nick,

I can understand this. But this LACP sceneio also not helping

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