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Catalyst 2960 Buffer miss

We have two Catalyst 2960 switches showing high buffer loss. The site is under heavy utilization, so we want to eliminate all possible issue.

Here is the switch status:

System image file is "flash:c2960-lanbase-mz.122-25.SEE3

The below buffer status is just after a reboot:

Public buffer pools:

Small buffers, 104 bytes (total 61, permanent 25, peak 175 @ 00:14:39):

60 in free list (20 min, 60 max allowed)

5219 hits, 50 misses, 114 trims, 150 created

0 failures (0 no memory)

Middle buffers, 600 bytes (total 30, permanent 15, peak 91 @ 00:14:34):

29 in free list (10 min, 30 max allowed)

1902 hits, 37 misses, 96 trims, 111 created

0 failures (0 no memory)

Big buffers, 1536 bytes (total 56, permanent 50, peak 56 @ 00:14:36):

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

5017 hits, 2 misses, 0 trims, 6 created

0 failures (0 no memory)

VeryBig buffers, 4520 bytes (total 10, permanent 0, peak 10 @ 00:14:39):

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

51 hits, 5 misses, 0 trims, 10 created

0 failures (0 no memory)

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

0 in free list (0 min, 5 max allowed)

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Huge buffers, 18024 bytes (total 0, permanent 0):

0 in free list (0 min, 2 max allowed)

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Interface buffer pools:

RxQFB buffers, 2040 bytes (total 150, permanent 150):

145 in free list (0 min, 150 max allowed)

136 hits, 0 misses

RxQ1 buffers, 2040 bytes (total 128, permanent 128):

2 in free list (0 min, 128 max allowed)

1007 hits, 12 fallbacks

RxQ3 buffers, 2040 bytes (total 16, permanent 16):

1 in free list (0 min, 16 max allowed)

1276 hits, 93 fallbacks

RxQ4 buffers, 2040 bytes (total 64, permanent 64):

1 in free list (0 min, 64 max allowed)

148 hits, 2 fallbacks

RxQ6 buffers, 2040 bytes (total 64, permanent 64):

0 in free list (0 min, 64 max allowed)

64 hits, 0 misses

RxQ7 buffers, 2040 bytes (total 96, permanent 96):

31 in free list (0 min, 96 max allowed)

1550 hits, 0 misses

RxQ8 buffers, 2040 bytes (total 32, permanent 32):

0 in free list (0 min, 32 max allowed)

1352 hits, 1324 misses

RxQ10 buffers, 2040 bytes (total 16, permanent 16):

1 in free list (0 min, 16 max allowed)

164 hits, 29 fallbacks

RxQ12 buffers, 2040 bytes (total 16, permanent 16):

0 in free list (0 min, 16 max allowed)

16 hits, 0 misses

RxQ15 buffers, 2040 bytes (total 4, permanent 4):

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

17643 hits, 17639 misses

RxQ11 buffers, 2040 bytes (total 4, permanent 4):

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

4 hits, 0 misses

2 REPLIES
Purple

Re: Catalyst 2960 Buffer miss

Check to see how busy the switch actually is , if its really busy you will see some buffer misses . You can get a pretty good idea of how busy it is at a particular time by using the "show controllers utilization" command which shows utilization for each individual port and also the % utilization of the switch fabric itself.

Bronze

Re: Catalyst 2960 Buffer miss

It's nothing to be concerned with. A buffer miss happens when the buffer falls below the minimum free buffers the switch tries to allocate. A miss indicates the processor had to create additional buffer space. It's nothing to be alarmed about, if you see failures.

If you notice all of the RxQ's that have misses, have 0 buffers in the free list, with a maximum of 4 allowed. If there are no free buffers, everytime there is a buffer request in that RxQ it will be considered a miss, as processor has to create a buffer for it.

If you do a show buffer on any of your switches the output will look the same.

http://www.cisco.com/en/US/products/hw/modules/ps2643/products_tech_note09186a0080093fc5.shtml

HTH

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