Configuring Token Ring Interface Features

2017-11-03 09:05:05

Problem

You want to configure a Token Ring interface.

Solution

The main thing that you need to take care to set properly for Token Ring interfaces is the ring speed:

Router2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router2(config)#interface TokenRing0 Router2(config-if)#ring-speed 4 Router2(config-if)#exit Router2(config)#end Router2#

You can also set the MAC address on a Token Ring interface:

Router2#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router2(config)#interface TokenRing0 Router2(config-if)#mac-address 0006.1111.aaaa Router2(config-if)#exit Router2(config)#end Router2#

And some routers can optionally support full-duplex Token Ring:

Router8#configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router8(config)#interface TokenRing0/8 Router8(config-if)#full-duplex Router8(config-if)#exit Router8(config)#end Router8#

Discussion

You can set the Token Ring's ring speed with the ring-speed command:

Router2(config)#interface TokenRing0 Router2(config-if)#ring-speed 4

The default for Token Ring interfaces is 16 Mbps. In this example, we have reduced the speed to support the older 4 Mbps standard. You need to be very careful when doing this, however, because ring speed mismatches can cause serious problems on Token Ring networks. Inserting a device with the wrong ring speed not only means that the new device can't use the ring, but it will disrupt communications among all of the other devices as well:

Changing MAC addresses is actually considerably more common than it is for Ethernet. However, just as we mentioned in Recipe 16.10, you need to be careful to ensure that MAC addresses are unique:

Router2(config-if)#mac-address 0006.1111.aaaa

Full duplex support on Token Ring interfaces is not actually part of the IEEE standard, but many vendors have started to support it. In fact, only a few of Cisco's Token Ring modules, which are designed specifically for full-duplex, support this command. However, if you have a router with this feature, and a Token Ring switch that also supports it, this can significantly improve your network performance.

You can enable full-duplex support, where available, with the full-duplex command:

Router8(config-if)#full-duplex

The default is half duplex.

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