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About ASIC in switches

why ASIC is used in switches not in hubs, how does it works and what is the main specification of this chip...

Thanks

Prakash

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New Member

Re: About ASIC in switches

A hub does not need an ASIC because it is not buffering frames, making a decision, and switching the frame out of the correct port. A hub simply is a repeater with a bunch of ports. It regenerates the actual signal on the wire.

A switch is a layer 2 device that makes a decision based on the layer 2 frame destination MAC address. The more ports you add to a switch the more processing a switch is doing. Just a few ports can be handled by software written to run on an off-the-shelf CPU. As the number of switch ports increase, the general purpose CPU using software solution can't keep up. The ASIC is basically a CPU that is not a general purpose CPU but is a CPU for making switching decisions very quickly. It can't be used for much else. This is similar to a high-end graphics card that has a special CPU for graphics processing that wouldn't be good for general applications. Hence the name, Application Specific Integrated Circuit.

Please rate post if helpful.

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Bronze

Re: About ASIC in switches

The FE ASIC is a system in which all routing decisions are made. Its complexity is usually greater than the complexity

of a MAC. The FE chip makes forwarding decisions at wire speed.

New Member

Re: About ASIC in switches

A hub does not need an ASIC because it is not buffering frames, making a decision, and switching the frame out of the correct port. A hub simply is a repeater with a bunch of ports. It regenerates the actual signal on the wire.

A switch is a layer 2 device that makes a decision based on the layer 2 frame destination MAC address. The more ports you add to a switch the more processing a switch is doing. Just a few ports can be handled by software written to run on an off-the-shelf CPU. As the number of switch ports increase, the general purpose CPU using software solution can't keep up. The ASIC is basically a CPU that is not a general purpose CPU but is a CPU for making switching decisions very quickly. It can't be used for much else. This is similar to a high-end graphics card that has a special CPU for graphics processing that wouldn't be good for general applications. Hence the name, Application Specific Integrated Circuit.

Please rate post if helpful.

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