- Bronze, 100 points or more
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!
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.
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.
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.
Jon, I've seen same as Giuseppe (I think the same as he's describing) on some (old) consumer switches. They might have two physical ports, both really the same port but the pins were different. I've also seen some of these switches where they might have a hardware DIP to reverse the pins on one switch port. All this before auto-mdix and to allow same patch cable as used by clients. (NB: Don't recall seeing this on "Enterprise" grade switches.)
this kind of question is becoming old times with the capability to detect what type of port to use: it is called MDIX.
However, your understanding is correct in small switches the uplink ports are thought to connect to another switch using a straight cable.
In the consumer space there are/have been hubs / switches with a double port 1: one to be used for a host and one to be used if you want to connect another hub/switch
Hope to help