Specifications
Table Of Contents
- About This Document
- Understanding Networking and IP Addressing
- Introduction to Networking
- Networking using IP
- Niagara Considerations
- Additional Information
- Configuration and Troubleshooting Tools
- Connecting on a LAN
- Connecting with Direct Dial
- Connecting to an ISP
- Using Security Technologies
- Configuration Files Used for Communication
- Glossary
- Index

Chapter 3 Connecting on a LAN
Connecting a New JACE Controller
Niagara Release 2.3
Niagara Networking & Connectivity Guide Revised: May 22, 2002
3–11
Table 3-3 illustrates the pinouts of a host’s Ethernet MDI port and a hub’s Ethernet
MDI-X ports and connection using a straight through cable. Note that the TX
(transmit) function of the PC connects (via the straight through cable) to the RX
(receive) function of the hub, and vice versa.
Note If you look at each end of a straight through cable, the ends would look identical
because they are pinned out the same.
In order to connect two hosts together (with matching MDI ports), or to connect two
hubs together (with matching MDI-X ports), you must use a crossover cable
1
. The
cable takes care of connecting the transmit to the receive on the matching ports by
crossing over the transmit and receive pairs within the cable.
Table 3-4 illustrates the pinouts of MDI ports on two hosts and the connection using
a crossover cable. Note that the TX function of Host1 (on pins 1 and 2) connects via
the crossover cable to the RX function of Host2 (on pins 3 and 6), and vice versa.
Note The crossover cable has one end wired like a straight through cable, and one end
wired differently.
Table 3-3 MDI to MDI-X connection.
NIC MDI port
Straight Through
Cable Used to Connect
Devices
Hub MDI-X port
Function Pin on
Port
Pin on
Port
Function
TX+ 1 ----------------------------------- 1 RX+
TX- 2 ----------------------------------- 2 RX-
RX+ 3 ----------------------------------- 3 TX+
RX- 6 ----------------------------------- 6 TX-
1. Sometimes hubs have a special uplink port, used to connect hubs together. The uplink port
actually is an MDI port rather than an MDI-X port. Use a straight through cable to
connect the uplink port on one hub to a regular (MDI-X) hub port on another hub.
Table 3-4 MDI and MDI-X pinouts.
Host1 MDI port
Crossover Cable Used to
Connect Devices
Host2 MDI port
Function Pin on
Port
Pin on
Port
Function
TX+ 1 1 TX+
TX- 2 2 TX-
RX+ 3 3 RX+
RX- 6 6 RX-