On 10/14/10 6:19 AM, Christopher Popp wrote:
Interesting ! People tend to think that because Internet bandwidth exceed our need atm, it's the same thing for mobile, which is absolutely not the case. In fact, carrier are fighting to limit the size of transmitted data, because cells can't sustain the load...To determine disconnects within the second timeframe, that means you'd have to configure TCP keep-alives to be occurring nearly once a second. Since the keep-alives may be bi-directional, assuming one per second, you'd be sending about 2 * 54 bytes * 60 * 60 * 24 * 30 = 267 MB of data a month per connection. I hope you don't have too many clients, and that the clients ("mobile device") don't have bandwidth limited data plans. ;-)I've also read a bit that cellular carriers can sometimes decide to drop TCP level keepalives. So, with a TCP timeout window in the second range, connections may end up being more flakey than they really are. The cellular carriers dropping TCP keepalives is one of the reasons we use application level keepalives (in addition to being able to configure keepalives on a per connection basis).
-- Regards, Cordialement, Emmanuel Lécharny www.iktek.com
