Networking Connectivity
Hubs
What is the Difference Between Class I and Class II Hubs?

CLASS I
A Class I repeater is allowed to have larger timing delays (140 bit times) because it translates line signals on an incoming port to digital form, and then retranslates them to line signals when sending them out on the other ports. This makes it possible to repeat signals between media segments that use different signaling techniques, such as 100BASE-TX to 100BASE-FX segments and 100BASE-T4 segments, allowing these segment types to be mixed within a single repeater hub. The translation process in Class I repeaters uses up to a maximum of 140 bit times so that only one Class I repeater can be used in a given collision domain when maximum cable lengths are used.

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CLASS II
A Class II repeater is restricted to smaller timing delays (92 bit times) because it immediately repeats the incoming signal to all other ports without a translation process. To achieve the smaller timing delay, Class II repeaters can only connect to segment types that use the same signaling technique, such as 100BASE-TX to 100BASE-TX hubs in that segments.

A maximum of two Class II repeaters can be used within a given collision domain when maximum cable lengths are used. Also, the cable that is used to daisy-chain the two Class II hubs together cannot be longer than 5 meters.

Segment types with different signaling techniques (e.g. 100BASE-TX, 100BASE-FX and 100BASE-T4) typically cannot be mixed together in a Class II repeater hub.

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Intel® Express 100BASE-T Hub Hub Class
Express 200 Series Stackable Hub Class I
Express 10/100 Stackable Hub Class I
Express 100BASE-TX Stackable Hub Class I
Express 100BASE-T4 Stackable Hub Class I
Express 330T Stackable Hub Class II
Express 100BASE-TX Standalone Hub Class II
Express 140T Standalone Hub Class II
Intel® InBusiness™ Fast Hubs Class II

This applies to:

Intel® InBusiness™ Hubs and Switches



Solution ID: CS-020686
Last Modified: 31-Mar-2008
Date Created: 04-Apr-2005
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