Network Performance Monitors Showing in excess of 100% utilization

Posted on 2005-05-09
Last Modified: 2010-04-17
Can someone please help resolve a disagreement here.  We have a Cisco CAT 5509 with several VLans set up.  All of the ENet ports are 10/100 along with several fiber Giga ports.

Out network performance monitor (Solarwinds) is showing that quite frequently we are well in excess of 100% utilization (as high as 400%).  My network analyst says that is because that even though the ports are 10/100, the actual routing supervisor can't handle more than 10 Meg and the traffic is queued up.

I have trouble buying it.  Why would Cisco have a switch with boards capable of running at 10/100/1000, but a supervisor unable to route the VLans at more than 10 Meg.  Secondly, perhaps I'm just being too logical, but how can you get more than 100% utilization?  It seems like either the tool (Solarwinds) is reporting incorrectly ... or the speed we are saying the port is running at (10 Meg) is incorrect.  If the speed is actually running at 100 Meg, then the performance of 40% is more understandable.

Any thoughts?

Question by:dfranklin80
    LVL 50

    Accepted Solution

    The backplane on the 5509 is made up of 3 seperate 1.2gb buses. Depending on which slot a card is in will determine which bus is used. The big question is how much traffic are you pushing through the backplane.

    A single 12 port 100mbps line card could put the bus utilization at 100%. That would, or course require all 12 ports to be transmitting at the same time. Make it two 24 port 100mbps line cards and it's not hard to see how you could max out the utilization.

    As for why Cisco would have a switch like that... It's an old switch chassis. Back when it was designed, they probably never considered that there would be 24 port 100mbps lines cards. Remember that pesky 640K RAM boundary on the first IBM PC? At the time I'm sure they thought "who would ever need more than 640K of RAM!".

    I seriously doubt the bottleneck is in the supervisor engine or route processor though.


    LVL 28

    Assisted Solution

    It depends which supervisor is in your 5509, but the Supervisor 3 can run up to 3 Gb/sec. NONE of them are limited to 10 Mb/sec. Where are you measuring your data exactly? On the port? I suspect that Solarwinds is assuming that a 100mb port is only 10mb, so the 100% threshold is lower than it should be- a software configuration issue, not a switch issue. Type "show port x/x" on the switch and it will tell you what speed and duplex it's actually running at.

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    Featured Post

    How to improve team productivity

    Quip adds documents, spreadsheets, and tasklists to your Slack experience
    - Elevate ideas to Quip docs
    - Share Quip docs in Slack
    - Get notified of changes to your docs
    - Available on iOS/Android/Desktop/Web
    - Online/Offline

    While it is possible to put two routes in place with the secondary having a higher metric, this may not always work. In the event of a failure that does not bring down the physical interface on the router the primary route is not removed. There is a…
    New Server  was moved from behind Router R2 f0/1 to behind router R1 int f/01 and has now address But we want users still to be able to connected to it by old IP. How to do it ? We can used destination NAT (DNAT).  In DNAT…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
    After creating this article (, I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

    779 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    15 Experts available now in Live!

    Get 1:1 Help Now