uplink port

[sarahr202]

hi everbody!

I have few questions about uplink port on a switch.

My understanding is uplink port is usually used to connect to another switch/hub.When using uplink port to connect to another switch uplink port ,we need staight through cable as pins inside the uplink port is rversed,thereby eliminating the need for cross-over cable. Am I correct? If I am correct, it means if we have to connect host?pc to uplink port, we must use cross-over cable.Is it correct?

thanks a lot!

[Joseph W. Doherty · Accepted solution]

The end-of-sales 2950T-24 has "24 10/100 ports and two fixed 10/100/1000BASE-T uplink ports". Don't know whether ports are just MDIX or auto-MDI/X, but "uplink" in this sense probably has more to do with the fact they support 10/100/1000 while other ports support only 10/100. If auto-MDI/X not supported, you'll likely need a cross-over cable to another switch's port.

[davy.timmermans · Accepted solution]

Hi Sarah,

In general an uplink port or another port is in general the same.

Between 2 switches: cross (uplink-regular port/ uplink-uplink/ regular-regular)

Between host-switch: straight

between router-router: cross

No matter if it's an uplink port or another port on the switch.

On switches you can configure mdix auto in interface config mode. With mdix auto configured you can use the 'wrong' cable between 2 switches(thus straight). The switch will correct the pin settings. You have to note that if you want to use "mdix auto", you have to put autonegotiation on (speed auto; duplex auto), at least on 1 port of the 2 if I'm correct.

But in general it's a good practice to disable mdix auto and use the correct cable.

If you doubt you can paste the link of the page where you found the information, or try to connect 2 switches.

[Mark Yeates · Accepted solution]

Sarah,

I think your original question has been answered I though I would add some advice to it. MDIX can be very handy in the field with using either a straight-through or

a crossover cable. I try to use the proper cable if at all possible for the following reasons:

1:) MDIX is a feature and like many other features it is always not guaranteed to work.

2:) In case you have to replace a switch that supports MDIX auto with one that doesn't makes an equipment swap much more difficult. I have learned this the hard way with a failed 3560 to 3550 swap.

HTH,

Mark