Direct connect cables for gigabit SFP ports?

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richms

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#168564 18-Mar-2015 14:00

I have 2 switches in my rack that are 8+2 ports - the 8 are all power over ethernet, and the 2 are mini gbic slots.

I have another switch with 4 empty mini gbics on it.

I know that you can direct connect with those cables on 10 gig switches, but it will be some time before I have 10 gig, and I need to free up another couple of POE ports ideally (or get a bigger switch which I dont want to do right now) - so if I pick up a couple of the direct connect cables, will they work between gigabit slots, or do they exclusively deal with 10gig ones?

Richard rich.ms

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#1261727 18-Mar-2015 14:33

SFP+ (10Gbps) cables don't seem to be backwards compatible with SFP ports: http://www.geekzone.co.nz/forums.asp?topicid=115068

xontech

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#1261750 18-Mar-2015 14:58

So in Cisco-world I think you are after something like this:
http://www.cisco.com/c/en/us/support/docs/switches/catalyst-6000-series-switches/21268-132.html#patch-cable

Would it be an option to get 2 x 1000BASE-T SFP's and use a normal patch cable (cross-over if necessary)?

Lias

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#1261751 18-Mar-2015 15:00

I'm pretty sure the "direct attach" cables are an SFP+ only thing, but I see no real reason why you couldn't just acquire 2 suitable SFP transceivers and an appropriate cable and go for gold?

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xontech

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#1261757 18-Mar-2015 15:04

Lias: I'm pretty sure the "direct attach" cables are an SFP+ only thing

The Cisco CAB-SFP-50CM direct attach cables were/are for use on older 3560's and 3750's on their 1G SFP (not +) ports. Whether these would work on non-Cisco devices is another question that I don't have the answer to.

Lias

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#1261768 18-Mar-2015 15:18

xontech:
Lias: I'm pretty sure the "direct attach" cables are an SFP+ only thing

The Cisco CAB-SFP-50CM direct attach cables were/are for use on older 3560's and 3750's on their 1G SFP (not +) ports. Whether these would work on non-Cisco devices is another question that I don't have the answer to.

This is Cisco.. I'd actually be mildly amazed if its not something proprietary :-)

Lias

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#1261773 18-Mar-2015 15:22

Actually Google says it is indeed proprietary.

Copper ( 2Gbps full duplex,Proprietary)

From http://www.cisco.com/web/partners/downloads/765/tools/quickreference/gbic.pdf

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xontech

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#1261778 18-Mar-2015 15:29

Ok. Guess at least it shows there are such things SFP based direct cables. Whether someone other than Cisco makes them would be interesting to know.

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#1261782 18-Mar-2015 15:40

xontech: Ok. Guess at least it shows there are such things SFP based direct cables. Whether someone other than Cisco makes them would be interesting to know.

SFP+

I have only ever seen 10Gbps DACs (Direct Attach Cable). They have SFP+ modules integrated.

If you have 1Gbps SFP ports then you just buy 1Gbps copper modules, then cable. 10Gbps is much more fussy.