Introduction to Data Communications
Previous	45g. MSAUs (cont'd)	Next

The connection from the Node to the MSAU is called the Lobe. The connection to the ring is via the Ring In and Ring Out connectors.

MSAUs are passive devices, there isn't any "intelligence" built-in. MSAUs come in 2 flavours:

• Unpowered - The unpowered MSAUs receive their power through the NIC cards.
• Powered. - The powered MSAUs plug in the wall outlet and have their own power supply built-in.

Token Ring connectors

The wiring between the NIC card and MSAU consists of 2 pairs of wires:

• Receive Pair - This pair receives packets from its upstream neighbour
• Transmit Pair - This pair transmits packets to its downstream neighbour

There are 4 types of connectors used with Token Ring:

• RJ11 connectors are used with older 4 Mbps systems
• RJ45 connectors with both 4/16Mbps systems
• Hermaphroditic connectors with IBM Cat 1 cabling
• The DB9 is used to connect the NIC card to the Hermaphroditic cable.

	Signal Lead	Hermaphroditic	RJ45	RJ11	DB9



	Tx+		Orange (O)	3	2	9

	Rx+		Red (R)		4	3	1

	Rx-		Green (G)	5	4	6

	Tx-		Black (B)	6	5	5

UTP wiring pinouts:

Note: The receive pair (Rx) is the center pair of wires. The transmit pair (Tx) the outside pair.

Introduction to Data Communications
Previous	Table of Contents	Next