determining the quantity through a T1 interface

[brian]

The question I have pertains to the bandwidth on a T1 interface of a Cisco router, and how to determine what its usage is.

I have read about T1s and until recently never thought more about a T1 being 1.54M until a software to measure utilization showed a T1 interface pulling 3M ( 1.5 in and 1.5 out). Now my question does a T1 have 1.54M for the transmit pair and 1.54 for the receive pair giving total combined possible bandwith of 3M.I also notices that this interface in question had its load interval set for 30 and input bits was 1.3M and output bits/sec 1.6M, how can this be possible under a 1.54 M limitation?? I do see that the outputQue is 30/32 with alot of drops and the input que 0/75 with no drops. Is the queing making it appear that more than 1.54M is passing through this T1, and if that is the case how can a solution be used to charge the customer for bandwidth utilization if counters are showing more bandwidth that is actually available.

thanks

brian@networkplus.com

[svermill]

I can only answer part of your concerns. Yes, there is 1.544 Mbps in each direction. I disagree with those who count both directions - a T1 is not 3 Mbps. It is 1.544 Mbps, duplex (as are nearly all circuits in the T-carrier world). No you cannot exceed 1.544 Mbps so your theory about lost packets being counted is probably right on the mark.

As for charges, I can't really help you. But who would charge down to the 1/100th or even 1/10th of a T1 in any given instant in time?

[dan.meier]

I believe the following MIB II variables can be polled to account for all traffic on an interface:

ifInOctets

ifOutOctets

ifInDiscards

ifOutDiscards

IfInErrors

IfOutErrors