Nexxus 5000 switches with GLC-SX-MM SFPs won't connect to 3750 switch

[tdennehy]

We purchased a pair of 5000's for a project, but are now just on the bench.  The 5000's talk to each other over the copper cable/modules, but they will not talk to a 3750-12 port gig switch.

We're usuing GLC-SX-MM SFPs, and we can see the red 850nm light emitting from the transmit side of each SFP.  We have tested the jumpers.  The SFPs and fiber jumpers work in some 3560 switches, so we know all those pieces are good.

Problem is, we just can't get a link up between the 3750 and the 5000.

Is there something special we need to do in the 5000 to make this interface come up?

There's an amber light on the front of the 5000 for every SFP slot, but as soon as I slide the SFP into the slot, the light goes out.  Not green or any other color, not even for a split second.

It is almost as if there is a different part number for the SFPs that go into the 5000, but haven't found that in any documention.

Thanks in advance,

Tim

[Reza Sharifi]

Tim,

The SFP is the same for both 3750 and Nexus

Just to clearify.  You are connecting a Gig interface on the 3750 to a Gig interface on the Nexus not 10Gig right?

Do you have the same problem if you connect 2 Nexus ports together?

Reza

[tdennehy]

Reza,

There are four copper 10gig interfaces on the right hand side of the switch all connected to another Nexxus 5k.  Those are working fine.  We want to take each switch and uplink it via gigabit SX to a 3750.  The traffic isn't going to be heavy between the 3750 and the Nexxus 5k.  The traffic will be significant between the two Nexxus boxes.  Hence the reason to uplink to a 3750.

The gig interface won't even come up on the 3750 or the Nexxus.  No link at all.

Interface isn't shutdown, and config for the interface has "speed 1000" in there.  I'm wondering if there's something else I need in the config to bring the interface up.  This is the interface that would normally connect to servers, but in this case using it to uplink to a 3750.

I see the 850nm red light in the SFP, so something else must be the issue.  Just don't know what it is.  Don't need "media-type" or anything in that configuration, do I?

Thanks,

Tim

[Reza Sharifi]

Tim,

You don't need media type since there 2 ports are natively fiber ports. One way to eliminate a faulty module is to connect one port to another in the same switch and same module on the Nexus switch.  Is this a 3750G? You are not connecting the 3750 to a fiber channel module right?

Reza

[tdennehy]

Reza,

I believe the switch's interface is eth1/1 (I don't have it in front of me at the moment).

I took the SFPs and put all of them in the 3750 and used the jumpers and jumpered between gig1/0/11 and 1/0/12 and the port immediately went into blocking mode, which is what I expected.

The SFPs work and the fiber jumpers work since I tested them all that way.

It appears as if I need to do something to the ethernet interface on the Nexxus switch.  Regarding the fiber channel module - I'm not sure what you mean.  The SFP ports on the left of the switch when looking at it are all 10/100/1000 ethernet SFP ports, aren't they?

Has to be something in the CLI on the eth1/1 that we're missing.

Thanks,
Tim

[Reza Sharifi]

Tim,

I am not familiar with Nexus series, but according to this link you need to use SFP for Fiber Channel connectivity and SFP+ for Ethernet.

Connecting to an Ethernet Port

Use an SFP+ transceiver to connect to an Ethernet port, as described in this section.

http://www.cisco.com/en/US/docs/switches/datacenter/nexus5000/hw/installation/guide/connect.html

HTH

Reza

[tdennehy]

Reza,

I think that is the problem!

Thanks,

Tim