Forwarding rate issue

Answered Question
Aug 7th, 2012

Hi all,

It is said that the forwarding rate of WS-C3750X-24T-E is 65.6 mpps.

Could any body tell me what is forwarding bandwidth, forwarding rate?

Is there any document to know how will the above switch reach the 65.5 mpps full forwarding rate performance? Any relevance between forwarding rate and uplink ports, network module extention .etc?

Please help to advise. Thanks a lot!

I have this problem too.
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Correct Answer by Joseph W. Doherty about 2 years 8 months ago

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Posting

The WS-C3750X-24T-E (not counting the stack ports, as noted in the spec) needs 1.488 Mpps x (24 gig ports + 2 10 gig ports) = 65.472 Mpps.

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Overall Rating: 5 (2 ratings)
Joseph W. Doherty Tue, 08/07/2012 - 10:46

Disclaimer


The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

Forwarding rate is how many packets the switch can "look at" and forward from one port to another.

Since frames/packets often vary in size, the necessary forwarding rate, in packets per second, can vary for the same bandwidth.

Minimal size Ethernet frames/packets needs a forwarding rate of 1,488 Kpps for 1 Gbps; for (standard) maximum size Ethernet frame/packets only needs a forwarding rate of 81 Kpps for the same 1 Gbps.

Often for newer devices, perforamance stats are quoted for the worst case, i.e. minimal size.

Just multiply number of ports, by 1,488 Kpps for each gig port.

For example, 48 Gbps ports, to guarantee line-rate/wire-speed would need about 72 Mpps.

thanhnguyenhoc Tue, 08/07/2012 - 19:27

Thank you for your help to clarify.

Would you please explain me sepcifically in the WS-C3750X-24T-E Cisco product, how it would need 65.5 mpps forwarding rate as stipulated in the datasheet?

(Ref http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps6406/data_sheet_c78-584733_ps10744_Products_Data_Sheet.html)

Thanks a lot!

Correct Answer
Joseph W. Doherty Wed, 08/08/2012 - 02:25

Disclaimer


The    Author of this posting offers the information contained within this    posting without consideration and with the reader's understanding that    there's no implied or expressed suitability or fitness for any  purpose.   Information provided is for informational purposes only and  should not   be construed as rendering professional advice of any kind.  Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In    no event shall Author be liable for any damages whatsoever  (including,   without limitation, damages for loss of use, data or  profit) arising  out  of the use or inability to use the posting's  information even if  Author  has been advised of the possibility of such  damage.

Posting

The WS-C3750X-24T-E (not counting the stack ports, as noted in the spec) needs 1.488 Mpps x (24 gig ports + 2 10 gig ports) = 65.472 Mpps.

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Posted August 7, 2012 at 8:56 AM
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