[c-nsp] Bundle member issue

[Walter Keen]

Take a look at UDLD.

If router A and router B have a fiber cable between them, and one strand, but not the other gets cut.
Lets say the strand that router A is using for TX (and therefore router B is using it for RX)

Router B should realize the link is down (likely in a UP/DOWN state), however router A is still receiving a signal from router B on the unaffected strand of fiber, so it thinks it is up.

If you are doing layer 2 switching, this can really have a big impact on spanning tree states, I've had it cause a large switching loop even with rapid-pvst running.

UDLD, when enabled on both ends in aggressive mode, negotiates a heartbeat-like communciations, and if that stops on either end, it is assumed you have a unidirectional link (exactly what happened to you) and shuts down the port in an err-disabled state.


Or, you could look at bidirectional optics, where they place tx and rx on two different wavelength's of a single strand.  Typically this makes stocking spares a little harder though, since you have to match them up in pairs (for example one tx=1310nm, rx=1490nm, the other is tx 1490nm, rx=1310nm)



If this is a platform that does not support UDLD, and you are using a routing protocol on this link, I would look into whether or not BFD is applicable.



----- Original Message -----
From: "Alejandro Aristizabal" <aaristizabal at mediacommerce.net.co>
To: cisco-nsp at puck.nether.net
Sent: Thursday, April 10, 2014 1:11:38 PM
Subject: [c-nsp] Bundle member issue


Good,


  I got an interface Bundle with 2 memebers, interfaces Gi0/0/0/18 and 
Gi0/0/0/19 (each one has two fiber cords, rx and tx), one fiber cord 
(tx) got damaged on interface Gi0/0/0/19 but this interface was still in 
UP UP state, the bundle still used this interface for traffic sending. 
¿if one cord got damaged why the interface was still in UP UP state... 
How can I make if this happen again, the interface Gi0/0/0/19 goes down ?


  thanks for read this message, and Id like some one help me solving 
this issue.







-- Alejandro Aristizabal Analista de Interconexión Email: 
aaristizabal at mediacommerce.net.co Móvil: 3206777514

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