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New Member

LAN switch maximum bandwidth

I am trying to determine the maximum bandwidth that can flow through a switch by using a formula that takes into account the number of ports and the port speed e.g. 48 Gigabit Ethernet ports. Can anyone tell me the formula to calculate the maximum bandwidth this could generate.

I am not sure if 48 giga ports could mean 24 cross connects at full duplex making 48 Gbps max for 48 ports??

2 REPLIES
New Member

Re: LAN switch maximum bandwidth

You can write formulas all day long, but it's the backplane bus speeds that ultimately determines the thoughput in a switch. Yes, there are about a million other variables (I'm not a Cisco Engineer), memory, buffers, asics, duplex settings,etc. A duplex Gigabit port is really 2 Gbs, 1 gig in and 1 gig out. So, in theory, that means 96 possible connections. 96 Gbs is alot of data, and the bus will be the limiting factor.

Try looking at these specs and see if it clears some things up for you (search for bus) :

http://www.cisco.com/univercd/cc/td/doc/pcat/ca1900.htm

http://www.cisco.com/warp/public/cc/pd/si/casi/ca6000/prodlit/k6kfy_wp.htm

Cisco Employee

Re: LAN switch maximum bandwidth

96 Gbps is max considering full duplex for all connections. If that much dedicated bandwidth you will need a Catalyst 6500 Modules that use the 256 Gbps Crossbar fabric. Otherwise, you can opp for lower bandplane or switching fabric using QoS.

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