FastHub Ports and Cabling Information

This appendix contains useful information about using the FastHub in Ethernet networks and contains the following sections:

FastHub Port Specifications

There are two types of ports on the FastHub: network ports and an uplink port. These ports have different pinouts and should be cabled accordingly.

Table B-1 is a summary of the ports on the FastHub 112T and FastHub 124T.

Table B-1: FastHub Network Ports

Model	Network Ports	Uplink Port
FastHub 112T	1x through 12x	12
FastHub 124T	1x through 24x	24

Network ports are internally crossed. Use an Ethernet crossover cable of the following type to connect any of these ports to another network device, such as a workstation, server, hub, switch, or router:

10-Mbps network devices--Category 3, 4, or 5 UTP cable
100-Mbps network devices--Category 5 UTP cable

Note When cabling an Ethernet network that contains autosensing 10/100 repeaters like the FastHub, use caution when using Category 3 and Category 4 cable. These cable types do not support 100BaseTX networks.

Table B-2 lists the pinouts for FastHub network ports.

Table B-2: Network Port Connector Pinouts

Pin	Signal
1	RD+
2	RD-
3	TD+
4	NC
5	NC
6	TD-
7	NC
8	NC

Uplink Port Description

The uplink port is not internally crossed. Use an Ethernet straigh t-through cable of the following type to connect one of these ports to another FastHub network port or to a n etwork port on another hub, switch, or router:

10-Mbps network devices--Category 3, 4, or 5 UTP cable
100-Mbps network devices--Category 5 UTP cable

Note Remember that you must connect the FastHub uplink port to an X port on a switch, router, or other hub.

Ethernet Cable Schematics

Figure B-1 is a schematic of the two types of cable (crossover and straight-through) used to connect the hub to network devices.

Figure B-1: Ethernet Cable Schematics

Ethernet Cabling Guidelines

This section provides cabling guidelines for determining how to build networks using FastHubs and other repeaters.

Repeater Types

The IEEE 802.3u standard defines two different classes of Ethernet repeaters, Class I and Class II.

The FastHub 112T and FastHub 124T are Class II repeaters. Following are the advantages of Class II repeaters:

Class II repeaters support multiple repeaters for building a single network. (Class I repeaters limit a network to one repeater.)
Class II repeaters support longer cable segments in single repeater configurations than Class I repeaters.

Switches with Internal Repeaters

Many switches have internal repeaters or plug-in repeater modules. In this type of device, the switch is actually attached to a port on the internal repeater. When connecting the FastHub to a switch, you should find out whether the port you are connecting to is a repeater port and then take one of the following steps:

If it is not a repeater port, the switch acts as an ordinary end-station, and you do not have to take any special steps.
If the port is a Class I repeater port, do not connect the FastHub or any other repeater to the port.

General Guidelines for Ethernet Networks

Table B-3 describes some guidelines when creating Ethernet networks with multiple repeaters. Exact figures could vary, depending on the manufacturer of the network equipment.

Table B-3: Ethernet Guidelines

Specification	10BaseT	100BaseTX
Maximum segment length	100	100
Maximum number of segments per network	5	Class II--2 Class I--1
Maximum number of hops¹	4	Class II--1 Class I--none
Maximum number of stations per segment	1024	1024
Cable type supported	UTP Category 3, 4, or 5	UTP Category 5

¹ Hops = Other repeaters.

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