Want to Connect, or Make Network Cables (CAT5) - Read This.

[JackMDS]

To make life, hopefully, simpler.

When A person talk to another person. Voice form the mouth goes to the other person ear(Crossover).

When NIC talk we call it Transmit (Tx), The other part need to get it to the Receive (Rx).

The Connections will look like this:

PC - Straight-Thru - HUB

Pin 1 TX+ -------------- Pin 1 RX+
Pin 2 TX- -------------- Pin 2 RX-
Pin 3 RX+ ------------- Pin 3 TX+
Pin 6 RX- ------------- Pin 6 TX-

When we connect two computers through NICs, we need CorssOver Cable. The Tx, and Rx in such a cable is inverted at the connector pins.
In this way, the Tx from one NIC will go to the Rx of the other NIC, and vice Versa.

The connection will look like this:

PC - CrossOver - PC

Pin 1 TX+ -------------- Pin 3 RX+
Pin 2 TX- -------------- Pin 6 RX-
Pin 3 RX+ ------------- Pin 1 TX+
Pin 6 RX- --------------- Pin 2 TX-

To make Cable maker life "easy" it was decided that the connectors on a Hub (or Switch) would be inverted at the Hub connectors.

This way the cable can be straight, and the inversion between Tx to Rx is done in the Hub connectors.

To make life still "easy" they added Uplink connection, in the Uplink the connector on the Hub is NOT crossed; it has the same Configuration as NIC.

Cable Modem was build to connect to NIC. If cable Modem is connected to Uplink (remember Uplink is on a Hub, but wired like NIC), a regular straight cable can be use. If Cable modem is connected to regular Hub connection, a Crossover cable has to be use.

NIC to NIC - Crossover Cable.
NIC to Hub - Straight (regular) Cable
NIC to Uplink - Crossover Cable.

Hub (regular) to Hub (regular) - Crossover Cable.
Hub (regular) to Hub Uplink - Straight (regular) Cable.

Cable/DSL entry on a Cable/DSL Router (WAN)is an Uplink.

If your Modem came with Straight Cable:
Modem to NIC - Straight (regular) Cable
Modem to Hub - Crossover Cable.
Modem to Uplink - Straight (regular)Cable

If your Modem Came with Crossover Cable:
Modem to NIC - Crossover Cable.
Modem to Hub - Straight (regular) Cable
Modem to Uplink - Crossover Cable.


If you need a Lot of Cables, or Cables cut to specific length, you can make your own cables, and save.

You need:

1. Cat 5 Roll.
2. End Plugs - RJ45.
3. Crimper ? A tool to put the RJ45 plugs on the cable.

These three items can be bought at Home Depot.

Instructions for making the cables can be found here:
http://duxcw.com/digest/Howto/network/cable/cable7.htm

 

[zman6911]

Looks good to me . I've been seeing lots of questions about that sort of thing lately (one of them was mine ). Prehaps we can get someone to bump this document up every now and then.

 

[spidey07]

maybe an explanaion of the difference between and MDI and a MDI-X port are in order?

When MDI is connected to MDI-X a straight thru cable is correct (the MDI-X does the cross, that's what the X is for)
When MDI is connected to MDI - you need cross over cable
When MDI-X is connected to MDI-X - you need cross over cable.

Now if I remember correctly a HOST NIC is a MDI port and almost all host ports on a hub/switch are MDI-X. straight thru here. What is refered to as a uplink port is MDI or has a switch for MDI or MDI-X operation.

moral of the story, if you don't get a link then try a crossover cable. A network technitian never goes on a job without a few of these in the bag. Just make sure you take a cable laber/sharpie and write Xover is big bold letters on both ends of the cable.

BTW - great post!!!

 

[JackMDS]

TTT

 

[JackMDS]

Bump

 

[JackMDS]

TTT

 

[shammerdan]

Thanks that is a big help

 

[JackMDS]

TTT

 

[osage]

very good and informative post, just the kind of thing I expect to find here. thanks

 

[JackMDS]

^^^