Buffer Usage

Unanswered Question
Feb 26th, 2008

I have a question regarding the usage of VeryBig buffers (1525 - 4520 bytes).

Configuration:

2970 ----Cat5e 1Gbps---- 3550 ----GigaStack 1Gbps---- 3550

See Visio attachment.

On both the 3550 switches I receive a high amount of Very Big buffer misses (25%). The 2970 shows no very big buffer misses and even no very big buffer usage at all.

The switches are not configured to handle frames larger than 1500 bytes neither are the servers, so there should be no usage of Jumbo packets. Why are the very big buffers used then?

Is there a tool to measure which ports receive a certain size of packets?

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aghaznavi Mon, 03/03/2008 - 07:32

Use the following commands for your buffer related doubts.

1.To display the details of the buffer usage pattern in a specified buffer pool, use the show buffers usage command in user EXEC or privileged EXEC mode.

show buffers usage [pool pool-name]

2.buffer public -- Enters buffer owner configuration mode and sets thresholds for buffer usage.

3. show buffers leak -- Displays details of the buffers that have leaked.

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