Cisco Catalyst 3560G backplane stats

I have two Cisco Catalyst 3560G 24 port switches and need to determine backplane bandwidth usage so I can purchase new 48 port switches. Does anyone know commands that can be used to determine the total backplane bandwidth usage statistics? Thanks
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IX_LongBowAsked:
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Ilir MitrushiIT Infrastructure and Security ArchitectCommented:
I don't think there are such commands. usually you use snmp capable software to monitor devices. Cisco Network Assistant can provide some degree of monitoring. For more detailed monitoring you can consider products such Orion from solarwinds etc.
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IX_LongBowAuthor Commented:
My goal is to see if I'm taxing the switch, or at what level I peak at it's performance. I found show process cpu history shows last 72 hours and last 60 seconds. Working on more goodies like this one.
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Don JohnstonInstructorCommented:
The design of most Cisco switches is such that it's pretty much impossible to over subscribe the backplane.

The 3650G-24 has a 32gig backplane and a forwarding rate of 38 million PPS. It would be impossible to overrun that.

The 3650G-48 has the same spec's so it's possible to overload the switch but still it would be... unusual.

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IX_LongBowAuthor Commented:
Thanks don, I believe you. But what if I want to purchase the 2960 low end to save money. I'm not using Layer 3 funcitonality on the 3560. How do I know i'm not going to over subscribe on that one? There has to be a way to know how much current usage as a baseline to determine what I can purchase. I need some technical method of extracting that data. Thanks
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Don JohnstonInstructorCommented:
Once again, the switches are designed so that it's virtually impossible to over-subscribe the backplane.

In the case of the 2960, the backplane is 32gbps. Which means you would need to have more than 32 of the ports configured for 1gbps and receiving data simultaneously.

Possible? Yes. (if you have a 48 port version) Likely? Not very.

If you even think that the switch will be receiving data at a rate greater than it's backplane speed, you shouldn't be considering that switch.

Keep in mind that the 2900's are designed to be access switches. Not distribution or core switches.
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IX_LongBowAuthor Commented:
donjohnston thank you for the input, but once again this question open is for a technical answer to gather the current statistics on my switch so I can present something to the CIO for purchase. I'm running iSCSI and Xenserver hosts with many Virtual machines. I'm sure I can be over taxing the switch at some point. When running show process cpu history I see something that Cisco tech support says I've reached 100% CPU at some point over 72 hours. I don't really understand why they said that, but they say it's indicated by all the numbers at the top of the graph.


     5555444445555544444555554444444444444445555544444555554444
100
 90
 80
 70
 60
 50
 40
 30
 20
 10  ****     *****     *****               *****     *****
    0....5....1....1....2....2....3....3....4....4....5....5....
              0    5    0    5    0    5    0    5    0    5

               CPU% per second (last 60 seconds)


                                           35453544533445345353
     5556665555555555555556655555555555555562121072005511191716
100
 90
 80
 70
 60
 50                                         * * ** *  * * ** *
 40                                        **** **** **** *****
 30                                        ********************
 20                                        ********************
 10  ****##***************###**************####################
    0....5....1....1....2....2....3....3....4....4....5....5....
              0    5    0    5    0    5    0    5    0    5

               CPU% per minute (last 60 minutes)
              * = maximum CPU%   # = average CPU%


     55555555555555555555577
     2433423433222332222225666666667666566666666666666666666666666666666666
100
 90
 80                       **
 70                       **
 60                       **
 50  ***********************
 40  ***********************
 30  ***********************
 20  ***********************
 10  #######################***********************************************
    0....5....1....1....2....2....3....3....4....4....5....5....6....6....7.
              0    5    0    5    0    5    0    5    0    5    0    5    0

                   CPU% per hour (last 72 hours)
                  * = maximum CPU%   # = average CPU%


Another interesting command is
show platform port-asic stats drop
I don't see any drops which is good.

This command shows which ports are mapped to which asics:
show platform pm if-numbers
This is valuable to know so I can separate my highest loaded ports across different asics.

If anyone can provide input on technical methods of gathering more data, I will award points. looking at switch health stats shows 0, unsure why. I've tried IE 6 as claimed supported on my version of IOS. I would like to simply know what throughput total on my switch, and if possible over a timeline like the above CPU stats.

I guess what I'm trying to figure out is why has Cisco tech support told me I've hit max CPU at some point along with combining throughput stats.


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Don JohnstonInstructorCommented:
I appreciate what you want, but I just don't think you'll find it on your platform.

I certainly can't see how they're coming up with 100% utilization based on your output. Highest I'm seeing is 76%

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IX_LongBowAuthor Commented:
Thanks, I thought 76 was the max also, not sure if I misunderstood what the tech said, but I asked him twice.
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Don JohnstonInstructorCommented:
If you got that information from Level 1 and 2 at TAC, I don't know if I would trust it.

:-(
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from_expCommented:
Ok, let me add some input also.
LongBow, modern L2 (and in some cases even L3) switches are designed so that there almost no backplane in classical meaning of this word (like in odler days, where big chassis had cards with ports and cards with processing power and the backplane could be a bottleneck there). Nowadays what you want to now is if your switch is wirespeed or not. if it is, then you can get full 24 ports x 1000 x 2 (duplex) throughput.
Even L3 routing/switching is implemented in hardware by means of network processors, so you can get wirespeed routing there.

However, some vendors can offer you oversubscribed switches, when 48 port switch can have only 32 wirespeed ports. You have to take this into account if you are going to put that switch under very heavy load.

So you can ask, what does CPU do? It do things around: ntp, logging, security things, encryption (ssh admin sessions), route table calculations - in case of L3 (resulting forwarding table will be put into network processors for wirespeed routing).
Good switch can have 100% of CPU utilization (if you try to ping it heavily, make maximum ssh sessions, etc) without any drop of real traffic.


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IX_LongBowAuthor Commented:
Bumping it up to see if anyone out there has some commands to extract data.
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from_expCommented:
what kind of data you want to extract now?
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IX_LongBowAuthor Commented:
I want a command to see all current 24 ports on my switch and how much bandwidth is being utilized just like the sh proc cpu command, over time.
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from_expCommented:
sh int counters
however, I would suggest to use snmp and cisco network assistant
(http://www.cisco.com/en/US/products/ps5931/)
to get info in graphical form

as a permanent utilization tool I would suggest cacti or whatsup gold
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