02-18-2016 03:20 PM - edited 03-08-2019 04:38 AM
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!
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02-18-2016 05:46 PM
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.
Table 3. Cisco Catalyst 4500 Supervisor Engine 7-E Bandwidth per Slot for Different Chassis
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.
02-18-2016 04:30 PM
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.
02-18-2016 04:46 PM
Thanks. This is the only line card
WS-X4748-RJ45V+E
02-18-2016 05:02 PM
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").
02-18-2016 05:28 PM
this is the SUP
WS-X45-SUP7-E
02-18-2016 05:46 PM
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.
Table 3. Cisco Catalyst 4500 Supervisor Engine 7-E Bandwidth per Slot for Different Chassis
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.
02-18-2016 05:47 PM
This is quite a good presentation on the Sup7E and Sup8E families.
http://d2zmdbbm9feqrf.cloudfront.net/2014/usa/pdf/BRKARC-3445.pdf
02-19-2016 01:01 PM
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?
02-21-2016 11:16 AM
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.
02-19-2016 10:41 AM
thank you. I will look over the document.
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