[c-nsp] DS3 Y-Cable

[Mark Rogaski]

An entity claiming to be Peder @ NetworkOblivion (peder at networkoblivion.com) wrote:
: 
: 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.  

It shouldn't.  Even with the cleanest timing reference, two live transmitters
combined via y-cable will clobber the framing with LCV's.  You need a
device that turns off the transmitter on the standby line card.  I don't
know of any Cisco product that coordinates this between cards separated by
more than a backplane.  

I suppose that there are devices that could function as a selector switch for 
a DS3, but the more I think about it, the more I think it would cause some
problems with OSPF or EIGRP.  It would also increase the complexity of your
implementation and move you SPoF from a Cisco chassis to another vendor
device which has an uncertain reliability.  

Mark


-- 
[]                        |
[] Mark Rogaski           |      The biggest difference between time and
[] wendigo at pobox.com      |      space is that you can't reuse time.
[] mrogaski at cpan.org      |      -- Merrick Furst
[]                        |
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