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Cisco CWDM SFP is treated as 100mbps SFP in 54xx
I added a couple of "Cisco compatible" CWDM SFPs to a 5448 and 5424 running 1.0.0.31. Ethernet link is up, I can "ping" between the switches across the fiber link. But "show port status" is showing the fiber ports as only 100mbps:
>g24 100M-Combo-F Full 100 Disabled Off Up Disabled Off
> (config-if)# int eth g24
> (config-if)# speed 1000
> Port g24 is a 100M-Fiber port and can be configured only to auto negotiation disabled mode
This is happening on both switches. "iperf" reports throughput between devices on one switch to be 800+mbps; but bandwidth between devices on separate switches as 90 mbps. So it seems that the traffic across the fiber link is truly limited to 100mbps.
If I move one of the SFP transcievers into a Cisco Catalyst, it are recognized as a gigabit port:
> catalyst#show interface gi5/1 | include media
> Full-duplex, 1000Mb/s, media type is CWDM-1590
I've successfully used Cisco LX and SX SFPs in Dell 5324s before. Could this be a problem where the Dell doesn't understand the media type reported back by the SFP, and so Dell decides to treat it as a 100-FX SFP? Is there a way to configure the Dell 54xx to force recognition of a fiber transciever as gigabit?
Zitibake
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May 1st, 2008 13:00
Dell support answered my query (2.5 weeks after submittal... they need to fix that "most questions answered in 24 hours" autoreply). Dell Support advises:
> I suggest trying Dell branded transceivers.
No kidding. Of course, Dell does not sell any CWDM SFPs (nor even a ZX SFP, for that matter), so this is no help at all. I suspect that this is a case of "nobody complained before", so there was no interoperability testing on SFPs other than 1000BASE-SX and 1000BASE-LX.
Zitibake
68 Posts
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December 18th, 2008 19:00
I tested CWDM optics in a Dell 2724 today, and it seemed to work just fine... well, fine if you upgrade to latest firmware. Some older firmware that came on the switch wouldn't work with any SFP I tried (SX, LX, Cisco, Finisar, whatever). When using CWDM optics, the receive level showed as "0 mW", but that was the only thing that seemed not to work.
I also noticed that two 2724s will talk to each other over fiber, even if one has the Combo port set to "no autonegotiation", while the other has the port set to autonegotiatie. On other fiber switches I've used, both ports need the same setting there, or link will not come up