Connect 5520 to 425 via fibre

[disturbedone]

I appear to be in a catch-22 situation but am sure there must be a simple answer to it.

I have a 5520-48T-PWR on SiteA and a 425-24T on SiteB. They're currently linked but have a Cat5 cable out of each, into an optic converter, to the other site and the optic converter to Cat5.

We're changing ISPs and they've given us SFPs that plug into port 48 (of the 5520) and port 25 (of the 425). On plugging this in to the 5520 the port now shows up grey but cannot be configured (it can be configured by clicking on the RJ45 of port 48. Some reading tells me that the SFP port only becomes active once it sees a connection.

At the other site I plugged the SFP in and connected the fibre but get no conneciton.....because, the switches can't be sending light because port isn't active because it can't see light from the other end.....because, the other end isn't sending light.....and there's the catch 22.

So how to I enable these ports to start sending light down the fibre so that they other end will see it and become active?

 

[anthonyanderberg]

As I recall the switch will change from "RJ45 mode" to "SFP mode" when the SFP is plugged in, but that might vary by switch - I've never had this problem with those models.

Another possibility that comes to mind is that the optics might not be 'Nortel-compatible' which would mean that the switches wouldn't recognize them. Basically the SFPs all have embedded manufacturer codes and some vendors (like Nortel and Cisco) look for their codes and some don't. Of course there are companies out there who sell SFPs coded to what ever vendor you'd like, provided you don't care about voiding your service contract.

Another thing you might also look at is the 425's stacking mode, I seem to recall that it had an effect on their SFP ports (in that when stacked the SFP ports disappear) but it's been a while so I'm fuzzy on the details.

 

[disturbedone]

I realised I had a multimode fibre patch cable. I have a single mode one and will try that this afternoon. I'll let you know.

 

[disturbedone]

After all that it was a layer 1 problem. Our ISP had confirmed on several occasions that the link was on fibres 5&6 but it turned out to be 7&8!!! Once that was sorted it came up straight away.

During the fault finding process I ran 'show sys-info' in CLI on both switches and saw the GBICs were listed as 'unknown' and 'unsupported' but it turns out that means little as it does actually work. I found some release notes for the 425 which said a known issue was listing GBICs as unsupported. The SFPs we're using aren't Nortel ones but they do work.