Cisco WS-3750G-12S-S switch problem

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Apr 21st, 2008
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I have a customer who has 3 of these switches stacked in Data Center. He has one switch Nortel 470-48T with 2 GBIC ports which they want to connect to the stack through fiber. The connectivity is not going through due to some reason. We have tried changing the GBIC ports both sides, fiber patch cables too many times but no luck. Is there any interoperability problem between the two switches. Pls help. The customer is having connectivity through copper on another switch for the time being.

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Jason Fraioli Tue, 04/22/2008 - 07:49
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Are you using the same media on both ends, single mode/multi mode?

Are you using the correct SFP modules on each end?


It sounds like you have a layer 1 problem.


Edit: Are you running any service that might cause those ports to go into errdisable?

rkalia1 Tue, 04/22/2008 - 08:45
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It was working earlier before we started managing the switches. The only extra configs put on the switches were AAA and SNMP. The modules used on Nortel switch are on 2 port 1000Base-X (GBIC)module [(47SX and 48SX)]. These are the uplink ports. The cisco 3750G-12S has 12 SFP-based ports. We are using Single Mode fiber.

Sushil Kumar Katre Wed, 04/23/2008 - 01:58
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Hi,


Which fiber standard are you using?


1000Base-SX Supports Multimode Fiber only.

1000Base-LX/LH supports MMF & SMF

1000Base-ZX suports SMF only.


I am not sure by "1000Base-X (GBIC)module [(47SX and 48SX)" you mean 1000Base-SX?


-> Sushil

rkalia1 Fri, 04/25/2008 - 07:51
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We are using MM fiber. Sorry for the error. It is a 2-port Gig SX module in the Nortel switch. The other side is Cisco WS-3750G-12S-S switch.

Lars Persson Wed, 04/23/2008 - 04:18
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Hi


If my memory is correct the Nortel will not negotiate the link.

Try "speed nonegotiate" on the interface in the 3750.


regs /Lars

Lars Persson Wed, 04/23/2008 - 04:21
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Hi


If my memory is correct the Nortel will not negotiate the link.

Try "speed nonegotiate" on the interface in the 3750.


regs /Lars

Sushil Kumar Katre Wed, 04/23/2008 - 04:22
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Hi speed negottiation is not supported on 1000base-X fiber standard. They work at 1000Mbps only.

Lars Persson Wed, 04/23/2008 - 04:36
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Hi


I beg to differ.


I have used this multiple times on LX and SX links.


According to Cisco command reference:


"speed nonegotiate"


"Except for the 1000BASE-T SFP modules, if an SFP module port is connected to a device that does not support autonegotiation, you can configure the speed to not negotiate (nonegotiate)."


Even if the speed WILL ALWAYS be 1000 there are still a negotiation. The gigabit ethernet demands auto negotiation on both ends otherwise the links will not go up. If one end dont negotiate you MUST set the other end to nonegotiate aswell, otherwise you dont get a link.


regs Lars

Sushil Kumar Katre Wed, 04/23/2008 - 04:39
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I beg your pardon, what I meant was the speed can't be anything other than 1000Mbps.

rkalia1 Fri, 04/25/2008 - 08:12
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Thanks sunil and Lars. It is enlightening. I will ask the customer to schedule a time for the test and will use the info u have provided.


Thanks again,

Raman

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