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Dear all
I have modelled Cisco catalyst 2948G.It has 48+2 ports which were
assumed as interfaces.Since it supports RFC1213,Interface Utilisation
of each port is calculated based on
800 * max( $ifInOctets,$ifOutOctets ) / $ifSpeed*timeInterval

Now i need to find "Bandwidth Utilisation" of Switch.In CISCO-STACK
MIB,node "sysTraffic" with oid ..1.3.6.1.4.1.9.5.1.1.8 states:
"Traffic meter value, i.e. the percentage of bandwidth utilization for
the
previous polling interval".

But i read somewhere it gives the value of the "Backplane Utilisation"
of switch and not "Bandwidth Utilisation".my question is
1.)What is the difference between two?
2.)If "sysTraffic" points to BackplaneUtilisation,how is Bandwidth
Utilisation of a switch

Thanks in advance
E.L.R.Arunkumar
www.adventnet.com

Arunkumar wrote:
> Dear all
> I have modelled Cisco catalyst 2948G.It has 48+2 ports which were
> assumed as interfaces.Since it supports RFC1213,Interface Utilisation
> of each port is calculated based on
> 800 * max( $ifInOctets,$ifOutOctets ) / $ifSpeed*timeInterval
>
> Now i need to find "Bandwidth Utilisation" of Switch.In CISCO-STACK
> MIB,node "sysTraffic" with oid ..1.3.6.1.4.1.9.5.1.1.8 states:
> "Traffic meter value, i.e. the percentage of bandwidth utilization for
> the
> previous polling interval".
>
> But i read somewhere it gives the value of the "Backplane Utilisation"
> of switch and not "Bandwidth Utilisation".my question is
> 1.)What is the difference between two?
> 2.)If "sysTraffic" points to BackplaneUtilisation,how is Bandwidth
> Utilisation of a switch
>
> Thanks in advance
> E.L.R.Arunkumar
> www.adventnet.com

I think you need to be a bit clearer about exactly what the "bandwidth
utilisation" of a switch means.

Imagine a switch in whch two ports are active, both 10M, and traffic is
streaming at 10M from port 1 to port 2, with nothing in the other
direction. What is the bandwith utilisation? 100% or 50%?

Now plug in a third 10M port which carries no traffic. Is the
utilisation now 66% or 33%?

Now change that silent third port from 10M to 100M. What's the
utilisation now?

It seems reasonable to me to give the utilisation of the backplane,
which is a known fixed capability.

Steve