cat4510 buffer size

[afsharki2]

Hello, we are connecting certain video streaming devices onto 4510 switchports.  How do you check the buffer size of the switchports?  I need to know if its enough for the bitrate that those video streaming devices will be transmitting. 

Thank you!

[Philip D'Ath]

There are quite a few cards and supervisors.  Can you post the output of "show inventory" please.

If you have different line cards, please indicate which one it is.

[afsharki2]

Thanks.  This is the only line card

WS-X4748-RJ45V+E 

[Philip D'Ath]

And which supervisor do you have, and is it the newer 4510 chassis type (if in doubt, please post the model number from "show inventory").

[afsharki2]

this is the SUP

WS-X45-SUP7-E 

[Philip D'Ath · Accepted solution]

You are making it really hard by only partially answering my questions each time.

I am going to assume you have a WS-C4510R+E chassis.

The 4700 series cards have a 48Gb/s connection to the back plane on a WS-C4510R+E.  If you are using a 4510R+E you will get 48Gb/s with a 1:1 contention ratio.  However if you have a 4510R-E, you only get 24Gb/s, and will have a 2:1 contention ratio.

http://www.cisco.com/c/en/us/products/collateral/switches/catalyst-4500-series-switches/data_sheet_c78-612364.html

Table 3.       Cisco Catalyst 4500 Supervisor Engine 7-E Bandwidth per Slot for Different Chassis

	Cisco Catalyst 4503-E Chassis	Cisco Catalyst 4506-E Chassis	Cisco Catalyst 4507R+E Chassis	Cisco Catalyst 4510R+E Chassis	Cisco Catalyst 4507R-E Chassis	Cisco Catalyst 4510R-E Chassis
Supervisor Engine 7-E (WS-X45-Sup 7-E)	48 Gbps/Slot	48 Gbps/slot	48 Gbps/slot	48 Gbps/slot	24 Gbps/slot	24 Gbps/slot

In the configuration given all buffering is done on the Sup7E.

http://www.cisco.com/c/en/us/products/switches/catalyst-4500-series-switches/models-comparison.html

The Sup7E has buffers for up to 128k packets from a shared pool of 32MB.

[Philip D'Ath]

This is quite a good presentation on the Sup7E and Sup8E families.

http://d2zmdbbm9feqrf.cloudfront.net/2014/usa/pdf/BRKARC-3445.pdf

[afsharki2]

You are correct, it is WS-C4510R+E chassis.  

When you say 128k patckets from a shared pool:  Do you mean a total of 128k packets can be buffered?  So, there is 1 buffer and it has 32mb shared that is shared between all the interfaces off the line cards?  What's the max that the shared buffere can allocate to a single interface?

[Philip D'Ath]

Yes, a maximum of 128,000 packets can be buffer, from a pool of 32MB.  So which ever of those two numbers run out first controls your limit (and the answer will depend on your distribution of packet sizes).

I guess if you were only using a single port on the entire chassis then the maximum it could allocated to a single port would be 32MB.

A Gigabit port can shift around 100MB/s in one direction.  So with 32MB you would get around 320ms of buffering with one port.

This that is an unrealistic case.

[afsharki2]

thank you.  I will look over the document.