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output buffers swapped out(?)

I'm using Cisco 7507 with VIP2 Boeards and PA-4T+/PA-8E on it. On my Serial Interfaces i recognize thousands of "output buffers swapped out"! What can i do to prevent from this? (...whitch buffers do i carefully have to increase?)

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Re: output buffers swapped out(?)

Output buffers swapped out is a feature of the RSP-based Cisco 7xxx systems. If the outbound interface transmit queue is full, then the packet is copied from a

hardware buffer to DRAM, then copied back to the transmit queue when there is room. If you are using fancy queuing (such as fair, custom, priority) then you

cannot disable this feature; however, when not using fancy queueing you can disable the buffer swapouts with the following interface command:

no transmit-buffers backing-store.

This prevents packets from being dropped in the output path, however it can add latency to the packet transit time. If your applications are very time-sensitive, then

it may be preferable to disable this feature.

Hope this helps,

Don

1 REPLY
Silver

Re: output buffers swapped out(?)

Output buffers swapped out is a feature of the RSP-based Cisco 7xxx systems. If the outbound interface transmit queue is full, then the packet is copied from a

hardware buffer to DRAM, then copied back to the transmit queue when there is room. If you are using fancy queuing (such as fair, custom, priority) then you

cannot disable this feature; however, when not using fancy queueing you can disable the buffer swapouts with the following interface command:

no transmit-buffers backing-store.

This prevents packets from being dropped in the output path, however it can add latency to the packet transit time. If your applications are very time-sensitive, then

it may be preferable to disable this feature.

Hope this helps,

Don

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