GBIC to Ethernet 10Base-T/100Base-TX/1000Base-T Uplink

I have a Cisco 2948G-L3 Switch. It has to two GBIC slots. I put a WS-G5483, Catalyst 1000BASE-TX GBIC Module in each GBIC slot.

I want to uplink it to a new Cisco 2960G-24T. It has four dual purpose ports that allow either a copper or a fiber uplink. Each dual-purpose uplink port has one 10/100/1000BASE-T ethernet port.

My question is to connect the Cisco 2948G-L3 Switch with the above

1000BASE-TX GBICmodules to the Cisco 2960G-24T 10/100/1000BASE-T ethernet port do I need a cross-over cable or straight through?


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We have a 2948G-L3 with 1000BASE-TX GBIC Module connected to a 3750 native Gig port and do NOT use a crossover, because the Gig port on the 3750 can be forced to MDI-X (implement a crossover) mode. As far as I recall, then GBIC's themselves do NOT implement a Crossover so we had to force one end. As you are using a GBIC at each end a crossover is required.

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Thanks Peter. I only have a GBIC on the 2948G-L3. The 2960 has a native Gig port. Since I don't know how to force a crossover on the

2960's Gig port, I will use a crossover. :-)
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I've been having trouble working out why anyone would even think of specifying or making a 1000base-T crossover cable. Since all four pairs in the cable are use bidirectionally there is no need to match up transmitters and receivers and a crossover cable just mixes up which bits in each octet are sent and received on a pair. I'm not disputing that such cables do exist, but they're different from any previously specified crossover (which means they can't be just for backwards compatibility) and I'm just baffled as to why anyone should have thought it was worth bothering.


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