I have an RSM fitted into one of my Cat 5500's and need to know how to calculate the utilisation of the router (or any router for that matter). I can check all manor of statistics (CPU, Packets per sec/min, memory used, etc), but none of them equate to a figure that is simple to explain to others. Is there a formula to calculate utilisation as a % ? If I was to explain to others that my router is 80% utilised for instance, I can make an argument for buying new equipment or upgrading. Can you help?
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Router Performance
- Thread starter tdonoghue
- Start date
Although it is sometimes hard to explain to our upper management, we use 2 statistics to justify upgrades.
1. CPU utilization
2. Bandwidth utilization (depending on the platform we either give this information on an interface basis - if line cards, PA, etc - or we simply state the highest utilization if a fixed interface router.
We generally try to explain these by stating that CPU is how much processing power the router is using to do it's work. And then explain that bandwidth is the physical limit of how much can be pushed through the router at one time. Todd Hethmon
thethmon@hethmon.com
1. CPU utilization
2. Bandwidth utilization (depending on the platform we either give this information on an interface basis - if line cards, PA, etc - or we simply state the highest utilization if a fixed interface router.
We generally try to explain these by stating that CPU is how much processing power the router is using to do it's work. And then explain that bandwidth is the physical limit of how much can be pushed through the router at one time. Todd Hethmon
thethmon@hethmon.com
ok,
to understand actual CPU utiliztionis easy - "show proc cpu" will give you 3 weighted moving averages (based on time) of the CPU utilization. Now *remember* you have procees context CPU work, and Interrupt context cpu work. The total is what you care about.
actuall pps performance is something else completely. The RSM is the equivilent of a RSP 2 (7500). It theoretically can handle about 143K pps in optimum or cef switching modes, however you are contrained by the two dma channels connecting the RSM to the backplane of the 5509. they are 400 Mbps (full duplex) i.e. 200 Mbps in any direction. this means that you are now limited based on packet size to something less than the cpu can pump (unless you only use 64 byte packets in your network. NOT!)
so for say 768 byte packets you'll get around 30Kpps
to understand actual CPU utiliztionis easy - "show proc cpu" will give you 3 weighted moving averages (based on time) of the CPU utilization. Now *remember* you have procees context CPU work, and Interrupt context cpu work. The total is what you care about.
actuall pps performance is something else completely. The RSM is the equivilent of a RSP 2 (7500). It theoretically can handle about 143K pps in optimum or cef switching modes, however you are contrained by the two dma channels connecting the RSM to the backplane of the 5509. they are 400 Mbps (full duplex) i.e. 200 Mbps in any direction. this means that you are now limited based on packet size to something less than the cpu can pump (unless you only use 64 byte packets in your network. NOT!)
so for say 768 byte packets you'll get around 30Kpps
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