Big buffers misses

Unanswered Question
Sep 28th, 2009

We have a WS-C4507R.

I see a about 520 Big buffers misses since 8 days(switch up time).

Can this casue any problem like disconnection or delay in the network.

How to solve this.

Thank you

I have this problem too.
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Giuseppe Larosa Mon, 09/28/2009 - 22:31

Hello Pica,

system buffers like big buffers are used to hold packets that need to be process switched = sent to main cpu.

Your device is a multilayer switch using CEF so most of packets and frames should be switched by CEF MLS without involving the cpu.

In other words these misses could have an impact on routing protocols messages (if used on the box) and not on user traffic.

To decide if 520 misses are acceptable or not you should compare it with the number of hits.

You should be able to use buffer autotuning or to manully increase big buffers but this should be done only if really necessary.

Hope to help

Giuseppe

intelligroup Mon, 09/28/2009 - 23:52

Thanks for the quick reply Giuseppe, Please find the output of sh buffer.

Actually are facing intermittent session freezes on the LAN.

Buffer elements:

497 in free list (500 max allowed)

151209424 hits, 0 misses, 0 created

Public buffer pools:

Small buffers, 104 bytes (total 51, permanent 50, peak 470 @ 1w1d):

50 in free list (20 min, 150 max allowed)

65113356 hits, 140 misses, 419 trims, 420 created

0 failures (0 no memory)

Middle buffers, 600 bytes (total 25, permanent 25, peak 161 @ 1w1d):

23 in free list (10 min, 150 max allowed)

433846 hits, 72 misses, 216 trims, 216 created

0 failures (0 no memory)

Big buffers, 1536 bytes (total 90, permanent 50, peak 113 @ 6d21h):

90 in free list (5 min, 150 max allowed)

6322418 hits, 518 misses, 1514 trims, 1554 created

0 failures (0 no memory)

VeryBig buffers, 4520 bytes (total 10, permanent 10):

10 in free list (0 min, 100 max allowed)

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Large buffers, 5024 bytes (total 0, permanent 0):

0 in free list (0 min, 10 max allowed)

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Huge buffers, 18024 bytes (total 1, permanent 0, peak 2 @ 1w1d):

1 in free list (0 min, 4 max allowed)

0 hits, 1 misses, 80 trims, 81 created

0 failures (0 no memory)

Interface buffer pools:

IPC buffers, 4096 bytes (total 135, permanent 2, peak 142 @ 1w1d):

3 in free list (1 min, 8 max allowed)

279233 hits, 56 fallbacks, 36 trims, 169 created

0 failures (0 no memory)

Header pools:

Catalyst 4000 buffers, 0 bytes (total 11696, permanent 11696):

11695 in free list (0 min, 11697 max allowed)

20176004 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

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