My (Rogers) cable connection has been pretty bad recently (channels 3 and 10 are particularly fuzzy—it’s analog, not digital cable). Not surprisingly, this has caused my cable modem to drop out and have to reestablish a connection a couple of times since it started. The poor connection of course means higher corruption (not necessarily dropped per se) which causes the TCP/IP stack to have to retransmit packets more often. Reduction of bandwidth throughput aside, I got to wondering if it increases the actual bandwidth usage. That is, if there is a high error rate on the line causing packets to have to be retransmitted:
- Does this increase a bandwidth monitoring program’s numbers?
- Does the ISP count the retransmitted packets toward the monthly cap?
Based on what I remember from my university networking courses and common sense, I have a feeling that the answer to both questions is yes, but I cannot reliably measure the first, and have no authoritative answer for the second. I’m wondering if maybe the retransmitted packets are acknowledged as being duplicates and thus not counted somewhere along the line.