Cat3K high memory consumption

Sergiy Pakhomov · ‎01-20-2015

Hello!

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.

Leo Laohoo · ‎01-20-2015

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.

Sergiy Pakhomov · ‎01-21-2015

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.

Leo Laohoo · ‎01-23-2015

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.