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- Re: Can't get a new 5400 to use SFP module uplink
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Can't get a new 5400 to use SFP module uplink
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08-10-2023 01:08 AM
I'm replacing an old Dell switch with a 5420M-24 with a fiber uplink. The old switch worked fine with it's SFP fiber connection but when I moved it to the 5420 I can't get the switch to talk to the network at all. I enabled Ethernet mode on the 5420 with the `disable stacking-support` command but that didn't help.
The U1 port seems to be active and processing traffic (the green light blinks) but the switch still doesn't acquire an IP address from our DHCP server and I can't even ping our firewall. I also tried installing a new SFP+ module in one of the uplink ports but I get the same result. As far as I can tell the ports are active and the packet counts are going up, but it still can't see anything on the other side of the fiber connection.
I'm new to the 5xxx series and have more experience with the older X440 stuff. I feel like I'm missing something simple (and stupid) but I just don't know what it might be.
Later...
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08-12-2023 04:47 AM
It turns out that the problem was stupid simple. I worked with Extreme technical support and we discovered that each end of the fiber connection was configured differently. :facepalm: One side was configured for 1000 full duplex and the other for 10000 full duplex (or something like that). It wasn't the SFP modules or the fiber link or anything "hard". I was so focused on thinking that it was something difficult I overlooked the simple stuff. I guess I thought that both sides of the link were configured to auto-config (like most UTP ports are) and didn't even consider that they might not be.
It was a little weird in that while we were testing it the TX stats would go up but the RX stats were zero; packets would leave the switch but nothing was coming back. Maybe that can help someone in the future if they have the same problem.
Later...
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02-15-2024 06:50 AM
This has been one of our most plaguing problems which upgrading to fabric. New switches dislike talking with older switches over fiber -- especially different brands. In my current case, I have a very small network (3 ports plus uplink) connecting over dark fiber. The switch is an older 8-port Netgear. It talks just fine to the 450. But we cannot get it to talk to the 5420. I have tried forcing the speed on the Netgear end, but with no success. I fear this is going to be a very expensive upgrade to reach three critical but very seldom used computers. Sigh...
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02-21-2024 08:10 PM
I saw this as well with a 210 connecting to a 5420 which replaced a B5. XIQ configured the port as auto-negotiate off (despite it being on in XIQ). The 210 got link for a second after SFP insertion, but the 5420 thought it had link the entire time. GTAC was very confused. Switching the 5420 to auto fixed it, then it broke again, then I switched it back to auto-negotiate off and it's been fine for a few weeks now.
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11-06-2023 04:12 AM
It's always simple things in this field. Glad you were able to resolve this!
