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Community Member

Switches and keepalives

Hi All,

We have two buildings, connected via 2 x 100Mb laser links. The switches on both ends are not Cisco, but are configured to be in a 'channel'. The lasers on both sides go into copper/fiber convertors, and then into the switches. The obvious problem here is that the switches will not notice when anything else other than the convertor fails (like laser, fiber etc). They will still have connectivity to the convertors, and thus happily pass traffic to the dead laser, which effectively brings both links down.

If I were to replace the switches with Cisco boxes, configure keepalives on all for ports, and form a channel, will a failure to receive keepalives not result in a port connected to a 'dead laser' shutting down (and thus resolving the problem)?

TIA for any comments.


Community Member

Re: Switches and keepalives

Jacques, this is an interesting scenario. I can't say definitively, but it appears that your idea may work.

The default for switch keepalives is 10sec and bundling the ports together in a FEC would bring some resiliency b/c an EtherChannel actually tracks which physical ports are active in order to avoid spanning tree loops (the Port Channel is treated as one large logical pipe for STP purposes).

I think it sounds like a good idea. Check out this page for more info on EtherChannel:

Good luck.

Community Member

Re: Switches and keepalives


I think I must test this with some 2950s we have. They will not carry the load under normal conditions, but before I put in a order for bigger boxes, I must be sure it will work (My idea of having 2 lasers for redundancy went a bit wrong!).



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