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4:1 oversubscribe

hello..there is 1 module in 4500 ws-x4418-gb and my client is trying to use it for uplinks to the edge switches...

i just read the documentation and it is mentioned it is 4:1 oversubscribe.. what does this mean and is it advisable to use it as a module for uplinks to the edge switches?

thanks

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Re: 4:1 oversubscribe

Oversubscribed or overbooked: this means that the aggregate port capacity is larger than the modules backplane throughput. Appearently 4 times in this case although I thought the backplane on the 4500 was 6Gb per slot.

You may use this module as long as the total traffic to your edge switches that flows through it does not exceed 6Gb. Otherwise it will evolve into a bottleneck. Besides, I am always reluctant to use Gb over UTP for trunks when they are not in the same wiring cabinet. Fiber is a much better solution for this.

The WS-X4406-GBIC (6-port) version of this module is still there because it allows for a non-overbooked connection. You will need three slots though, to furnish the same number of ports.

regards,

Leo

2 REPLIES

Re: 4:1 oversubscribe

Oversubscribed or overbooked: this means that the aggregate port capacity is larger than the modules backplane throughput. Appearently 4 times in this case although I thought the backplane on the 4500 was 6Gb per slot.

You may use this module as long as the total traffic to your edge switches that flows through it does not exceed 6Gb. Otherwise it will evolve into a bottleneck. Besides, I am always reluctant to use Gb over UTP for trunks when they are not in the same wiring cabinet. Fiber is a much better solution for this.

The WS-X4406-GBIC (6-port) version of this module is still there because it allows for a non-overbooked connection. You will need three slots though, to furnish the same number of ports.

regards,

Leo

New Member

Re: 4:1 oversubscribe

Hi,

This means that 4 Gi-Port share a chip that can handle 1Gb.

On the 4418 (AFAIK) port gi0/1 and 0/2 both can handle 1Gb non-Oversubcribed Port 3-6, 7-10, 11-14 and 15-18 share 1GB.

So , if you plan to make a Etherchannel, keep in mind to use for ex. Port 3 und 7 ..

see http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/8.1/configuration/guide/gigabit.html

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