LC to SC Autonegotiation

[davisirs]

I've got a Cisco 3750 switch with an LC connector autonegotiation (multi/single-mode) GBIC connecting to a Cisco 4507 switch with an SC connector multi-mode GBIC that periodically drops the connection. I've heard that it's the autonegotiation of the LC NIC between multi-mode and single-mode that may be causing the problem. Can anybody shed some light on this particular issue? Thanks in advance.

[pradeepde]

This below document is intended to help determine why a port or interface is experiencing problems. This document applies to Catalyst switches running CatOS Software on the Supervisor or Cisco IOS. System Software on the Supervisor.

http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a008015bfd6.shtml

[eduardo_ojeda]

Hi,

Did your problem was solved? I would like to know how, because I´m having much the same problems.

Regards,

Eduardo

eduardo.ojeda@hp.com

[davisirs]

Hi Eduardo,

No, the information in the post did not help in resolving my problem. I'll continue to look and let you know when I find a solution.

[cxa23]

I have encountered a similar problem with a 10Gbe interface on a 3750. Every 2 to 3 hours or so the link would drop between switches and then restore itself 30 to 45 minutes later, repeating this process indefinitely.

The switches were connected via SMF backbone approximately 10kM in length. What I discovered was one side of the link had Single-Mode patch cords between the patch panel (FDP) and the switch while on the other side there were multi-mode patch cords between the patch panel (FDP) and the switch. Once I replaced the MM patches with SM, the problem cleared itself up immediately.

My suggestion would be to examine the patch cords, riser, and backbone fiber between your switches and insure it is all MM or all SM and not a mix of the two.

Good Luck.