Backplane speed

Answered Question
Jan 17th, 2009

how we now the Back plane speed of any switch ?

or where we can founded it

I have this problem too.
0 votes
Correct Answer by Joseph W. Doherty about 7 years 9 months ago

Backplane or fabric speed noted for many Cisco switches in the attachment.

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Overall Rating: 5 (2 ratings)
sswiderek Wed, 01/21/2009 - 14:33

Question: Ratings for the 2940-8 are 2,700,000 and 3.2 and for the 2960-8 are 2,700,000 and 16. The performance is the same but the fabric is different. Is the 2960 faster? What do these ratings mean?

Jon Marshall Wed, 01/21/2009 - 14:41

Switch fabric is the actual backplane speed of the switch so if you had a 24 port 10/100/1000 switch with a 16Gbps switch fabric then if all ports were running at 1Gbps that would be

24 x 1Gbps = 24Gbps

switch fabric = 16Gbps

so you could get contention between the ports and the switch would not run at wirespeed for all ports. If however you had a 24 port switch with a 32Gbps switch fabric

24 x 1Gbps = 24Gbps

switch fabric = 32Gbps

so all ports could run at wirespeed and there would be no contention.

Hope this makes sense.


sswiderek Wed, 01/21/2009 - 14:49

I think i understand. So for the 2940-8, (8 x 100Mbps)+(1 x 1 Gbps) = 1.8 Gbps. So with the fabric at 3.2Gbps you could never overload the switch, right? If so then the 2960-8 with a fabric of 16 just has more headroom, right?

Jon Marshall Wed, 01/21/2009 - 14:59

"If so then the 2960-8 with a fabric of 16 just has more headroom, right?"

Yes correct. Because of the switch architecture you will find that some switches models within the same swith family where family is 2960 or 3560 etc. have more switch fabric than they need.



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