I have two interfaces on my ADSL router named internal and external.

I would like to graph the bandwidth of one of the interfaces. What is the difference between the two, as the traffic I presume will pass through both?

regards,

Usually you can tell the difference between an internal and external interface by the ip of each. Usually the internal interface will have an ip in the private ip range. These consist of the following ranges.

10.0.0.0 - 10.255.255.255
172.16.0.0 - 172.31.255.255
192.168.0.0 - 192.168.255.255

Check the ip of your interfaces and the one that is in the above range is the internal interface.

Thanks. I can identify which is internal/external but was wondering the different in traffic bandwidth. I originally though the same traffic will pass through both. I thought about it a bit more and discovered there will be a slight difference in traffic.

If I monitor the internal interface, it would be a more accurate as all traffic will pass through (home network <--> internet).

If I monitor the external interface, the traffic would be slightly lower (or higher if getting DOS'ed) as the router would be blocking some malicious traffic from the internet which are not destined for my network.

Hope this makes sense.

regards.