Jostein wrote: .... > The cumulative response time (latency) is effectively doubled by this, which > could affect email transmission. Especially in high-traffic periods. > > Routing is in general determined by routing agreements between different ISPs > and their network operators, which could contribute to explain why the problem > is different from ISP to ISP. > > Jostein
Jostein, In short: unless the latency time is several (many!) seconds (as opposed to tens or hundreds milliseconds) mail traffic will not be affected. If the latency is a few seconds occasionally you can see messages arriving out of order. If you can reliably browse american websites, e-mail traffic will not be affected by the latency time. In a bit more detail: 1. Packet routing is a dynamic process. Besides, it might not be (and very often it is not) symmetric, i.e. packets going from you to another computer could be following a different route from those coming back. 2. If the latency is high, but steady (i.e. doesn't fluctuate wildly), this should not cause TCP packets being lost 3. SMTP protocol implementation is such that if transmission is not successful, it will be retried until completed successfully or until the delay due to retries exceeds some preset time (usual default - 5 days). 4. SMTP protocol (high level protocol used for transmitting e-mails) uses so-called TCP connection (low-level packet transmission protocol), which is capable of retransmitting dropped packets (TCP packets) and reassembling them in the right order if they came out of order due to mildly fluctuating latency. 5. Traceroute that you are using to check packet routing has different implementations and could use different packets (in most cases those are so-called ICMP packets). Depending on the implementation of the router, these packets can have much-much lower priority then the TCP packets, or sometimes could be completely blocked by some ISPs. So, while usually one can get a rather adequate picture using traceroute, in some weird cases, such a picture could be irrelevant to the real situation. I've seen such cases. As far as I can tell, the response time from your ISP to the US does not exceed 200-300 ms which is rather standard for transatlantic connection. Igor
