Cisco SFP module interfaces

[tojorand]

I have been looking at Cisco's 1000Base-SX SFP modules and have a question: Will they plug into a regular gigabit ethernet port (such as the gigabit ports on a Cisco 2950T-24)?

I have to confess that Cisco's literature gets me confused sometimes, and I would appreciate any help clarifying it. Thanks in advance for your help!

 

[ADB100]

No - SFP's are smaller than regular GBICs - hence the same Small Form Pluggable GBIC. Take a look at the images on CCO to see the differences:

2950 with standard GBIC slots:

http://www.cisco.com/image/jpeg/en/us/guest/products/ps4556/c1122/cdccont_0900aecd800acd9b.jpg

3560 with SFP slots:

http://www.cisco.com/image/jpeg/en/us/guest/products/ps5528/c1122/cdccont_0900aecd800de536.jpg

HTH

Andy

 

[tojorand]

OK. Thanks for your reply.

I see that they will not plug into a regular GBIC port, but will an SFP plug into a RJ-45 type connection gigabit port?

 

[ADB100]

Nope again - you can though get 1000BaseT SFP GBICs (GLC-T) and then plug standard Cat5/6 RJ45 cables in.

If your switch has SFP slots then you must buy Cisco SFP GBIC's of whatever media you require:

GLC-LH-SM - GE SFP, LC Connector, LH Transceiver
GLC-SX-MM - GE SFP, LC Connector, SX Transceiver
GLC-ZX-SM - GE SFP, LC Connector, ZX Transceiver
GLC-T - GE SFP, RJ45 Connector, 10/100/1000BT Transceiver

If your switch has Standard GBIC slots then you must buy GBIC's of whatever media you require:

WS-G5484 - 1000BaseSX GBIC-short wavelength GBIC (multimode fibre only)
WS-G5486 - 1000BaseLX/LH GBIC-long wavelength GBIC (multimode or singlemode fibre)
WS-G5487 - 1000BaseZX GBIC-extended reach GBIC (singlemode fibre only)
WS-G5483 - 1000BaseT GBIC-Gibabit Ethernet over copper GBIC

Andy

 

[Jsteve]

Andy,
Do you know the diff between the LX and LH?

I could never get a straight answer from ciscoTAC. They claim that there is no difference and that they are interchangeable.

But if try to hook up a LX/LH on one end and a LX on the oter, it will not work.

Jsteve

 

[tojorand]

Thanks for all your help

 

[ADB100]

Jsteve

The actual documentation on CCO state that the GLC-LH-SM is LX/LH and the WS-G5486 is also LX/LH. I have sucessfully connected LH SFP's to LH GBIC's without problems - what issues have you seen? I know over Multimode Fiber cabling that you must use mode-conditioning patch cables with LX/LH GBIC's (SFP's or 'standard' GBIC's). Note however that mode conditioning patch cables for 62.5 ?m fibers have a different specification from the mode-conditioning patch cables for 50 ?m fibers.


Andy

 

[Jsteve]

The situation I had was a SM fiber connection with about a -12db lost on the fiber and good OTDR readings. I had a LX/LH standard on both ends and one of the GBICs went bad. I replaced it a GBIC that was labled only LX (or maybe LH, cant really rmember) and the link would not come up. At first I assumed that I had another bad GBIC but I set it up in a lab enrironment (with antenuators of course) and I had two LX labled GBICs an it worked, but when I interchange the GBICs LX <-> LX/LH and it did not work. I also tested this in a mm environment with the same results.

 

[ADB100]

Weird one Jsteve. You took the best approach and raised a TAC case - What did Cisco say?

 

[Jsteve]

They stated that it should have worked, but that i may have been due to the difference in manufacturers. That is all I got.