what is the public buffer in I/O memory??

Answered Question
Mar 26th, 2009
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Hi all,

as reading the boot of CEF,

I have a question.

what is the public buffer??

it is shown in "show buffer"


SG1#sh buffer

Buffer elements:

498 in free list (500 max allowed)

36934785 hits, 0 misses, 0 created


Public buffer pools:

Small buffers, 104 bytes (total 1024, permanent 1024):

1000 in free list (128 min, 2048 max allowed)

27361469 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Medium buffers, 300 bytes (total 3000, permanent 3000):

2989 in free list (64 min, 3000 max allowed)

5041587 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Middle buffers, 600 bytes (total 512, permanent 512):

509 in free list (64 min, 1024 max allowed)

555036 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Big buffers, 1536 bytes (total 1000, permanent 1000):

999 in free list (64 min, 1000 max allowed)

2962078 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

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

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

215938 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Large buffers, 9240 bytes (total 8, permanent 8):

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

13 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Huge buffers, 18024 bytes (total 2, permanent 2):

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

84 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)


Interface buffer pools:

EOBC0/0 buffers, 1524 bytes (total 2400, permanent 2400):

1094 in free list (0 min, 2400 max allowed)

1306 hits, 0 fallbacks

1200 max cache size, 781 in cache

15449495 hits in cache, 106 misses in cache

IPC buffers, 4096 bytes (total 672, permanent 672):

541 in free list (224 min, 2240 max allowed)

1218839 hits, 0 fallbacks, 0 trims, 0 created

0 failures (0 no memory)

Private Huge IPC buffers, 18024 bytes (total 2, permanent 2):

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

0 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)

Private Huge buffers, 65280 bytes (total 2, permanent 2):

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

18 hits, 0 misses, 0 trims, 0 created

0 failures (0 no memory)


Header pools:



in above output,

"Interface buffer pools" is used by interface processor to store the packet switched.


but I don't know

what kind of the packet is used by "Public buffer pools"


is there anyone to explain this in detail??


Correct Answer by Giuseppe Larosa about 8 years 2 months ago

Hello Sanghee,


the public buffer pools are the system buffer they are used to hold the packets that need to be process switched = need to be sent to main cpu for deep inspection.


These buffers are organized in different sizes when a packet arrives if there is space it is hold on a buffer of the correct size.


see

system buffer tuning


http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00800a7b80.shtml


Hope to help

Giuseppe


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Correct Answer
Giuseppe Larosa Thu, 03/26/2009 - 01:20
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Hello Sanghee,


the public buffer pools are the system buffer they are used to hold the packets that need to be process switched = need to be sent to main cpu for deep inspection.


These buffers are organized in different sizes when a packet arrives if there is space it is hold on a buffer of the correct size.


see

system buffer tuning


http://www.cisco.com/en/US/products/hw/routers/ps133/products_tech_note09186a00800a7b80.shtml


Hope to help

Giuseppe


Sanghee Han Thu, 03/26/2009 - 17:29
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thanks for your help.

it's a great help for me


Thanks again.

and have a nice day :-)

Sanghee Han Thu, 03/26/2009 - 17:39
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then I wonder when the router executes process-switching.


if a packet is arrived at the router

then it needs to be process-switched

because the router has no cache entry.


so the packet is stored in interface buffer pool or public buffer pool?

or

is the packet copyed from interface buffer pool to public buffer pool?


Giuseppe Larosa Fri, 03/27/2009 - 03:39
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Hello Sanghee,

thanks four your kind remarks

the public address pools are those used for process switched traffic.


Hope to help

Giuseppe


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