nanog mailing list archives

Re: Cable-Tying with Waxed Twine


From: Jared Mauch <jared () puck nether net>
Date: Thu, 25 Jan 2007 10:21:34 -0500


On Wed, Jan 24, 2007 at 09:41:22PM -0700, Larry Beaulieu wrote:
The other thing I found interesting; The use of Zip Ties on Copper Cabling 
is frowned upon by BICSI.  Velcro preferred.

Something to do with the compression on a twisted-pair cable caused by 
over-tight nylon cable ties screwing with their twist rates, and thus 
changing their Crosttalk characteristics...

Yep.

For starters, the stuff that Dan Mahoney is looking for is properly known as
waxed linen lacing cord.  In a past life I used to order the stuff made
by Ludlow Textiles through Graybar, their part # back then was 89039323. It's
not always in stock in individual stores.

As for plastic ties (TyRap is the brand name for the Thomas & Betts version)
they may be easy to use, but they do have several functional drawbacks, 
including:

1) difficulty in maintaining consistent tension from tie to tie, and as
   a correlary it is comparatively easy to overtighten one, risking 
   compression-related damage to the underlying cabling, or as mentioned above,
   increasing crosstalk when using twisted-pair cables
2) can harden and/or become brittle over time, eventually failing under stress
3) typical background vibration causes them to tend to chafe the sheaths of the
   wiring that the ties are in direct contact with, over a period of years.


        This (and the other superbowl related emails) reminds me of
a time I had a DS3 go down (on superbowl sunday).  It had some
chronic errors that would pop up where it would go down  seemingly
randomly.  What we found out after a few more outages was that this (LD)
carrier who placed their facilities next to train tracks had a
more chronic issue of a train going by and causing LOS or errors on the
circuit where they handed it off on coax to the ILEC/CLEC.

        Getting someone dispatched to look at the circuit on that
sunday was problematic to say the least ;)

        - jared

-- 
Jared Mauch  | pgp key available via finger from jared () puck nether net
clue++;      | http://puck.nether.net/~jared/  My statements are only mine.


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