C3750X slow?

[johnlloyd_13]

Hi all,

I was setting up a new stack of 3750Xs a couple of days ago. And I've observed that issuing commands such as ''show run' and 'write mem' took a while compared to ISRs. Is this normal behavior? I thought switch's (an L3 in this case) operation would be fast due to it's combined (stackwise) backplane? Appreciate someone's enlightenment.

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[Leo Laohoo]

I was setting up a new stack of 3750Xs a couple of days ago.

How many in a stack?

Normally, I'd keep my 3750X stack to a maximum level of 5.  Anything more than 6 and you'll occassionally observe "lag".  Get's worst when you do an inter-stack "range" command.

I don't know if this "issue" is fixed in the 3850.  However, currently the new 3850 can support only up to four (4) switches in a stack.  Future software release will allow up to nine (9).

[johnlloyd_13]

Hey Leo,

There are only 3 switches in the stack. So, is the lag "normal" or is it something I should worry about? Saving the config takes around 10-15 sec.

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[Leo Laohoo]

There are only 3 switches in the stack. So, is the lag "normal" or is it something I should worry about? Saving the config takes around 10-15 sec.

That's not normal and that ain't right.

What is your IOS and what are your switch models?  Better yet, post the "sh version". 

[johnlloyd_13]

hi leo,

please find show output below and let me know what else are your thougths. thanks!

#sh ver

Cisco IOS Software, C3750E Software (C3750E-UNIVERSALK9-M), Version 15.0(2)SE, RELEASE SOFTWARE (fc1)

Technical Support: http://www.cisco.com/techsupport

Copyright (c) 1986-2012 by Cisco Systems, Inc.

Compiled Fri 27-Jul-12 23:26 by prod_rel_team

ROM: Bootstrap program is C3750E boot loader

BOOTLDR: C3750E Boot Loader (C3750X-HBOOT-M) Version 12.2(53r)SE2, RELEASE SOFTWARE (fc1)

3750X uptime is 3 hours, 51 minutes

System returned to ROM by power-on

System image file is "flash:/c3750e-universalk9-mz.150-2.SE/c3750e-universalk9-mz.150-2.SE.bin"

This product contains cryptographic features and is subject to United

States and local country laws governing import, export, transfer and

use. Delivery of Cisco cryptographic products does not imply

third-party authority to import, export, distribute or use encryption.

Importers, exporters, distributors and users are responsible for

compliance with U.S. and local country laws. By using this product you

agree to comply with applicable laws and regulations. If you are unable

to comply with U.S. and local laws, return this product immediately.

A summary of U.S. laws governing Cisco cryptographic products may be found at:

http://www.cisco.com/wwl/export/crypto/tool/stqrg.html

If you require further assistance please contact us by sending email to

export@cisco.com.

License Level: ipservices

License Type: Permanent

Next reload license Level: ipservices

cisco WS-C3750X-48P (PowerPC405) processor (revision A0) with 262144K bytes of memory.

Processor board ID FDO1630V1NS

Last reset from power-on

10 Virtual Ethernet interfaces

1 FastEthernet interface

156 Gigabit Ethernet interfaces

6 Ten Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

512K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : 60:73:5C:64:3F:80

Motherboard assembly number     : 73-12553-06

Motherboard serial number       : FDO16301HMJ

Model revision number           : A0

Motherboard revision number     : A0

Model number                    : WS-C3750X-48PF-E

Daughterboard assembly number   : 800-32727-03

Daughterboard serial number     : FDO16412HK0

System serial number            : FDO1630V1NS

Top Assembly Part Number        : 800-31324-03

Top Assembly Revision Number    : B0

Version ID                      : V03

CLEI Code Number                : COMJZ00ARC

Hardware Board Revision Number  : 0x04

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 54    WS-C3750X-48P      15.0(2)SE             C3750E-UNIVERSALK9-M

     2 54    WS-C3750X-48P      15.0(2)SE             C3750E-UNIVERSALK9-M

     3 54    WS-C3750X-48P      15.0(2)SE             C3750E-UNIVERSALK9-M

Switch 02

---------

Switch Uptime                   : 3 hours, 51 minutes

Base ethernet MAC Address       : 60:73:5C:00:6D:00

Motherboard assembly number     : 73-12553-06

Motherboard serial number       : FDO162911U9

Model revision number           : A0

Motherboard revision number     : A0

Model number                    : WS-C3750X-48PF-E

Daughterboard assembly number   : 800-32727-03

Daughterboard serial number     : FDO16432P7Y

System serial number            : FDO1629Z1K0

Top assembly part number        : 800-31324-03

Top assembly revision number    : B0

Version ID                      : V03

CLEI Code Number                : COMJZ00ARC

License Level                   : ipservices

License Type                    : Permanent

Next reboot licensing Level     : ipservices

Switch 03

---------

Switch Uptime                   : 3 hours, 51 minutes

Base ethernet MAC Address       : 44:03:A7:47:C8:80

Motherboard assembly number     : 73-12553-08

Motherboard serial number       : FDO16482NMH

Model revision number           : A0

Motherboard revision number     : A0

Model number                    : WS-C3750X-48PF-S

Daughterboard assembly number   : 800-32727-03

Daughterboard serial number     : FDO164515V4

System serial number            : FDO1648Z2YN

Top assembly part number        : 800-31324-07

Top assembly revision number    : B0

Version ID                      : V04

CLEI Code Number                : COMJZ00ARD

License Level                   : ipbase

License Type                    : Permanent

Next reboot licensing Level     : ipbase

Configuration register is 0xF

---

#sh switch

Switch/Stack Mac Address : 6073.5c64.3f80

                                           H/W   Current

Switch#  Role   Mac Address     Priority Version  State

----------------------------------------------------------

*1       Master 6073.5c64.3f80     15     3       Ready

2       Member 6073.5c00.6d00     5      3       Ready

3       Member 4403.a747.c880     5      3       Ready

[Leo Laohoo]

Switch 2: 
License Level                   : ipservices
License Type                    : Permanent
Next reboot licensing Level     : ipservices
Switch 3: 
License Level                   : ipbase
License Type                    : Permanent
Next reboot licensing Level     : ipbase

I'm not sure this is the cause but something for you to look at.

15.0(2)SE

This could be the culprit.  You have but two choices:

1.  Downgrade your IOS to 12.2(55)SE7; or

2.  Upgrade to 15.0(2)SE1.

I'm still in the middle of testing 15.0(2)SE1 so I can't give you anything interesting with this IOS. 

[johnlloyd_13]

hi leo,

thanks for spotting the license difference! will feedback this to my client.

will appreciate if you could share the output of your test and if it's due to an IOS bug.

[Leo Laohoo]

No problem.  Still in early stages of testing 15.0(2)SE1.

If this version works well, I'll have to eat alot of humble-pie!

[patrick.preuss]

Hi

Are you using sfps?
What Type you are using?
Have you configured a power stack?


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[johnlloyd_13]

hi patrick,

no SFPs in use and all uplinks are RJ45.

yes, it's setup to use power stack.

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

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Posting

I thought switch's (an L3 in this case) operation would be fast due to it's combined (stackwise) backplane? 

Generally a L3 switch's forwarding performance (its data plane) is much, much faster than a software based router's, such as an ISR.  Command line operations might actually be slower as the control plane might have a slower CPU in a L3 switch vs. the CPU in a software based router.

[johnlloyd_13]

hi joseph,

aren't new generation switches made to process data (either command line or data packets) faster these days?

do you have a link which says CPU are slower in a L3 switch?

[Joseph W. Doherty]

Disclaimer

The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.

Liability Disclaimer

In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.

Posting

aren't new generation switches made to process data (either command line or data packets) faster these days?

Current generation switches are often faster in the data plane but unknown how much faster they're designed to be in control plane.  I'm sure there's some improvement there too.

do you have a link which says CPU are slower in a L3 switch?

John, no I don't.  That's one reason I wrote "might".  The other reason, it really depends on what two device you compare.

Several years ago, I did some testing of RIP on a 2811 and 3750; trying to find the impact as I turned down the timers.  As I neared minimum timer values, the 3750's CPU usage began to really climb compared to the 2811.  At first I was quite surprised until I remembered the performance of L3 switches is derived from it's special hardware for forwarding.  Their CPU only has to contend with control plane functions while an ISR's CPU has to contend with both data plane and control plane functions.  I.e. "normally" a L3 switch isn't as dependent on its main CPU for performance which means a slower CPU might be used.

Also a couple of years ago, I accessed a production CRS-1 for the first time.  I was really surprised by how "slow" command line processing appeared to be.

[patrick.preuss]

Hi

Lics Must be The same.

Can you provide a Show proc cpu Hist and Show proc CPU sort?

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