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Cat3K high memory consumption

Sergiy Pakhomov
Level 1
Level 1


I've noticed interesting behaviour in Cat3k.

Some time ago our management system started to send notifications that one of our switches (C3560E) have more than 80% memory utilization. I looked into it and saw that this was pretty much the same situation for almost a year that the switch is monitored. Recently it just grown a little, that gave more than 80% but before it was almost 80%.

Show version output suggesting that switch has 128M of memory:

cisco WS-C3560E-48TD (PowerPC405) processor (revision F0) with 131072K bytes of memory.

IOS version - 15.0(2)SE6

I took it to the lab, erased config to see if that was the problem (nothing fancy there - basic L2/L3 switching, marking traffic, few static routes, less than 40 vlans)

show memory after erasing config still showing high memory utilization and what is interesting total memory is less than 50M when it should be something around 128M.

                     Head            Total(b)     Used(b)       Free(b)         Lowest(b)     Largest(b)
Processor    4A4601C    49259992    36919476    12340516    11127860     8379892
      I/O         6800000      8388608      5571764      2816844       2729744     2723328
Driver te       2C00000     4194304      106744       4087560       4087560     4087560


show proc memory output have a few lines that seems to consume more memory than others, although two of them freed the memory.

 PID TTY   Allocated               Freed         Holding           Getbufs            Retbufs Process
   0  0     71388632            38470628      28752828                      0                    0 *Init*          
   0  0     18227488            11537036        6776320          7012651        1472786 *Dead*          
  11  0    495977460        495977460             7160                      0                    0 Licensing Auto U
  12  0    2531364                2531932             7160                      0                    0 Image License br
Then I looked at our other Cat3K switches and noticed similar behaviour - some of the memory that should be there is not shown in show memory or other outputs.
For example Cat 3750-X output with 512M memory onboard:
cisco WS-C3750X-12S (PowerPC405) processor (revision A0) with 524288K bytes of memory.
IOS version - 15.0(2)SE7
show memory output
                             Head         Total(b)        Used(b)         Free(b)     Lowest(b)      Largest(b)
Processor    49FC5DC     443826520    46730440    397096080   390523216    374185540
      I/O         1E000000       16777216    12931564        3845652       3745400        3822188
Driver te        2C00000         4194304                44        4194260       4194260        4194260
Another one: 3550 with 64M of memory
Cisco WS-C3550-12G (PowerPC) processor (revision A0) with 65526K/8192K bytes of memory.
show memory output
                          Head        Total(b)         Used(b)       Free(b)         Lowest(b)       Largest(b)
Processor    1D2A360     36779168     18901208     17877960       16839776      10271320
      I/O         80000000      8388608       3025900       5362708         5241044        5294688
So, the question basically is:
1. Can I do something to decrease memory consumed (free the memory from the Dead proccess or something else)
2. Is it normal that big part of the memory is not shown and not used (or is it used for something else)?
Thanks in advance.




3 Replies 3

Leo Laohoo
Hall of Fame
Hall of Fame
IOS version - 15.0(2)SE6

This is "normal" when you're running crappy software like the 15.0(2)SE train.  


I will never recommend Cat 3K to run anything but 12.2(55)SE9.  If you need features only found in 15.0(2)SE then stick with 15.0(2)SE4. 

To be fair we use extensively this train on 4900M and 4500 platforms and it's going ok for now.

And 15.0(2)SE6 is considered MD release, release notes don't have anything on the memory side of issues (there is seems to be a bug with HTTPS which we don't use and disable explicitly).

I'll try to use the suggested by you release, but don't have too much hope that situation will change.

And 15.0(2)SE6 is considered MD release, release notes don't have anything on the memory side of issues (there is seems to be a bug with HTTPS which we don't use and disable explicitly).

I agree.  But there are some bug Cisco's identified that will never be published to the publlic.  


Let us know how you go.