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Subinterface PVC Utilization

Hi !.

Iam using Cisco 7507 with FrameRelay for data connectivity.Iam making use of subinterfaces.Each Mail interface has many subinterfaces and each subinterface corresponds to a PVC.How can i acertain the Utilization ( Input/Output Rate) for a specific subinteface.

Show Int <main interface> gives the following:

5 minute input rate 7000 bits/sec, 5 packets/sec

5 minute output rate 21000 bits/sec, 9 packets/sec

How do i calculate/acertain per subinterface utilization.

Any help would be appreciated


Re: Subinterface PVC Utilization

You can use SNMP to query the router for its (sub)interface statistics.

One very popular way to do this is with mrtg ( ) which produces nice looking graphs of the utilization per day, week, month and year.



New Member

Re: Subinterface PVC Utilization

Thnx Herbert,

You mean to say that there is no CLI Command to see the statistics.

The main objective is to analyse how does the router calculate Sub-interface statistics.You mean that the tool MRTG ( we are indeed using it ) has it's own method of calculating subinterface statistics.But how do i validiate that the data ( Graphs) displayed is Authentic..


Re: Subinterface PVC Utilization

From the CLI, I only know "show frame-relay pvc" which shows byte and packet counters.

I'm not sure how mrtg does it exactly, but I guess it reads the byte counters using snmp and calculates a 5-min average by substracting the previously read value and deviding the result by the 300 (the number of seconds elapsed since the previous retrieval).

You can also retrieve the snmp values yourself, e.g. on a *nix host with ucd-snmp-utils installed:

snmpwalk ifName

this will list all interfaces on the router with their ifIndex, e.g.

ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.29 = Se5/0/0.1

ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.30 = Se5/0/0.2

ifMIB.ifMIBObjects.ifXTable.ifXEntry.ifName.31 = Se5/0/0.3

so to get the usage of Se5/0/0.3 you would do

snmpget ifInOctets.31

snmpget ifOutOctets.31

resulting in something like this:

interfaces.ifTable.ifEntry.ifInOctets.31 = Counter32: 417901239

interfaces.ifTable.ifEntry.ifOutOctets.31 = Counter32: 228052103



New Member

Re: Subinterface PVC Utilization

Hi Herbert,

Yes, i agree with you.I also found a similar sort of method in the cisco site.

Thnx for the help.

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