<Help --> Having trouble trying to activate a GigE connection>

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1

Group,

                I am having an issue with activating a Gige interface
between a Cisco 7206 VXR w/IO-1GE module to a 7606 w/sup720-3bxls
connecting to a line module WS-X6416-GBIC. I have verified that the
GBIC-MMF have good light reading and the MMF fiber jumper are not
reversed. The GigE connection comes up briefly for about a few seconds,
takes a burst of errors and goes down. I have tried to set the speed to
nonegotiate on both ends, set one end to speed auto. No dice. Here is
the copy of the configuration. On my 7606 I show that the GigE
interface is up/up but on the 7206vxr I show down/down. Any help will
be greatly appreciated. Thanks!

This is the Cisco 7206VXR configuration.

interface GIabitEthernet0/0

no ip address

duplex full

speed 1000

media-type gbic

no negotiation auto

This is the Cisco 7606 configuration.

interface GigabitEthernet1/8

description AR4-DLLSTXHW-GE0/0

no ip address

speed nonegotiate

Michael Ruiz

Network Engineer

2

Hello Michael:

From: Michael Ruiz [mailto:mruiz@telwestservices.com]
Sent: Tuesday, November 24, 2009 8:02 AM
To: nanog@nanog.org
Subject: <Help --> Having trouble trying to activate a GigE

Group,

                I am having an issue with activating a Gige interface
between a Cisco 7206 VXR w/IO-1GE module to a 7606 w/sup720-3bxls
connecting to a line module WS-X6416-GBIC. I have verified that the
GBIC-MMF have good light reading and the MMF fiber jumper are not
reversed. The GigE connection comes up briefly for about a few
seconds,
takes a burst of errors and goes down. I have tried to set the speed
to
nonegotiate on both ends, set one end to speed auto. No dice. Here

is

the copy of the configuration. On my 7606 I show that the GigE
interface is up/up but on the 7206vxr I show down/down. Any help will
be greatly appreciated. Thanks!

I don't think there is any reason to have hard-set speed and duplex,
particularly between two Cisco's. Why not just set *both* sides (you
can't set just one) to auto-negotation - 'no speed nonegotiate' on the
7606 side. Is this a straight shot, single fiber pair between the two
or are there intermediate junctions or optics? It sounds like you have
questionable fiber or optics in the path. It could be the fiber itself
or the GBICs on either side.

Regards,

Mike

3

I actually have seen where you have to hard set to speed 1000 to get this
type of link up, even Cisco to Cisco.

  -Scott

4

I don't think there is any reason to have hard-set speed and duplex,
particularly between two Cisco's. Why not just set *both* sides (you
can't set just one) to auto-negotation - 'no speed nonegotiate' on the
7606 side. Is this a straight shot, single fiber pair between the two
or are there intermediate junctions or optics? It sounds like you have
questionable fiber or optics in the path. It could be the fiber itself
or the GBICs on either side.

Mike,

  I tried setting the 7206 to auto, and the 7606 to nonnegtiate,
however, no dice. We put light meter on both ends of the GBIC and light
readings are at -20, which are applicable. Between the two routers are
MMF and it is straight shot with no transport equipment in between.

5

I have seen this behavior caused by a mismatch of SFPs, SX on one side
and LX on the other.

/p

6

I have seen this behavior caused by a mismatch of SFPs, SX on one side
and LX on the other.

We found the problem. After going through 5 MMF GBICS we found one that worked.