[c-nsp] DS3 Y-Cable

[Dave Temkin]

The interfaces would definitely have to be in shutdown mode for this to
work.

I've seen instances where even when they're in shutdown they still send
clock on the signal, so in reality you really need to have the router
powered off while connected like this.

So, basically, if you'd like to keep the box powered off except in a DR
scenario, this will work... But if you want to keep it powered on and up,
this is a bad idea.

As far as redundancy otherwise, you'd have to look into an external box
to do automated switching in the event of LOS.
I know they're made for T1's but not sure if they're made for DS-3's...
One thing you have to keep in mind is that you're adding another point of
failure and you have to weigh the pros and cons..

-Dave

 On Wed, 15 Mar 2006, Peder @ NetworkOblivion wrote:

> 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
>
>
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