Cisco Systems VIP-4R/4T manual Token Ring Distance Limitations, Token Ring Speed Considerations

VIP Port Adapter Functions

Token Ring Distance Limitations

The maximum transmission distance is not defined for IEEE 802.5 (Token Ring) networks. Shielded twisted-pair (STP) cabling is most commonly used for rates of 4 and 16 Mbps. Twisted-pair cabling is more susceptible to interference than other types of cabling; therefore, the network length and repeater spacing should be planned accordingly.

Token Ring Speed Considerations

Before you install the 4R port adapter, determine the ring speed (4 or 16 Mbps) of each ring to be connected to the server. There is no factory default for the interface speed; you must set the speed of each interface (within the setup command facility or with the ring-speedcommand) before you bring the interface up and insert it into the ring with the no shutdown command.

Note If an interface has an undefined or incorrect ring speed and is not shut down, the ring will beacon. This effectively takes the ring down and makes it inoperable.

4R Port Adapter LEDs

The 4R port adapter’s enabled LED (shown in Figure 16) goes on to indicate the following status of the 4R port adapter:

•

•

•

•

Enabled for operation

Correctly connected to the VIP card

Receiving power from the VIP card

Contains a valid microcode version

If any of these conditions is not met, or if the initialization fails for other reasons, the port adapter’s enabled LED does not go on.

Figure 16 4R Port Adapter LEDs

ENABLED			IN	- RING	TOKEN RING
					Mbps
				4/16
0	1	2	3		H4489

When a Token Ring interface is configured by using software commands, two additional LEDs for each port indicate the following:

•In ring—Goes on when the interface is currently active and inserted into the ring; off when the interface is not active and is not inserted into a ring.

•4/16 Mbps—Goes on if the interface is operating at 16 Mbps; off when the interface is operation at 4 Mbps.

VIP-4R/4T Installation and Configuration 33