100 Mbit/s hubs

The principle operation of 100 Mbit/s hubs is like the 10 Mbit/s hubs. However, the hubs for 100 Mbit/s ETHERNET have to be additionally distinguished to class I and class II hubs.

Class I hubs (or class I repeaters) are able to connect two segments with different transmission media. For this purpose the complete data stream has to be decoded on the receiving side and encoded again on the transmission side according to the transmission medium. This conversion process leads to higher delay times. Due to this, only one class I hub is permitted within one collision domain.

In contrast, class II hubs support only one transmission medium. No conversion of the data stream is required. This leads to shorter delay times compared with class I hubs. This is why for two segments with a maximum length of 100 m each, up to two class II hubs which are again connected to each other via a 5 m long segment can be used within one collision domain.

Use of a class II hub