[c-nsp] DS3 Y-Cable

[Peder @ NetworkOblivion]

We have a channelized DS3 into a Cisco 7505 CT3IP card.  We want a 
backup in case something in the 7505 chassis dies, so we have an 
identical chassis with the same cards, config and everything ready to 
go.  The theory is that if something goes down, we just move the cables 
and we're good to go.

A "ccie" said that we could just use a DS3 Y-cable to connect both DS3 
cards to the one telco circuit and if one fails, it will just 
automatically failover to the 2nd one.  That just doesn't seem right to 
me.  There is signaling in both directions, so how could the cable block 
signaling one way and allow it the other way, but in the event of a 
failure, it is smart enough to allow the other part to work.  It just 
doesn't sound right.  Was he just plain wrong, or am I missing something?

If this won't work, is there some way to provide DS3 redundancy so that 
if one of the cards goes down, we don't have to move the cable?  That's 
difficult if you aren't on site and don't have "hands" available.  Thanks.

Peder