[c-nsp] LH/LX and Mode Conditioning Cable

[Bill White]

We had a rare condition where we saw 3-4 trunk errors a day on three
LH/LX<---30am MMF---->LH/LX links to our core switches (out of about 45
total links we have over a LX/LH-MMF scenario).  

We verified DMD issue by putting in a mode conditioning patch cable.
Later we just put SX modules in place every time we suspected DMD
(Differential Mode Delay).  This is a fairly rare situation, and my
advice would be to change out optics to SX in instances where physical
layer fiber errors are being realized and you're sure patch cables and
terminations are true and correct.

Mode conditioning patch cables get pricey depending on length required.
And we hate having to keep stock for such a rare optical phenomena.


Bill White, CCNP, CNE, SCP
Network Specialist II
Department of Information Technology
City of Henderson
240 Water Street
P.O. Box 95050
Henderson, NV 89009-5050
 
702-267-4350
Cell 702-249-0183
Fax 702-267-4302

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Peder @
NetworkOblivion
Sent: Wednesday, April 25, 2007 11:05 AM
To: Cisco-NSP Mailing List
Subject: [c-nsp] LH/LX and Mode Conditioning Cable

I know that Cisco says it is required, but does everybody else seem to
agree that you need a mode conditioning cable if you use an LH/LX
GBIC/SFP over multimode fiber?  Or is it a case of "may work, may not
work, YMMV"?

Also, has anybody ever bought SFP's from here?
http://www.memorydealers.com/lxsfpgbforci.html

LH SFP's for $59!  That is really cheap, but it makes me wonder if it is
"too good to be true".  Rather than buy some off vendor, maybe I am
better off buying some used Cisco LH SFP's to save $$.

Peder

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