Thread: [Under consideration] 3G Throttler (Battery Saver)
View Single Post
TA-t3 is offline TA-t3
2009-11-27 , 11:05
Posts: 3,841 | Thanked: 1,079 times | Joined on Nov 2006
#25
Originally Posted by jjx View Post
TCP/IP can't resume a connection if your IP address changes. That was unusual in the old days, but now it's common. I've seen it happening sometimes when hopping from one 3G base station to the next, and of course it always changes IP address when switching between 3G and WLAN.
This is true. It can be handled though, by layering a virtual network on top of the physical network, for example.

Also, fwiw, TCP/IP doesn't do very well if your connection is down for, say, 30 seconds. It may recover, but it'll sometimes take another 30 seconds to notice after the connection comes back. If your connection is down for 120 seconds, TCP/IP won't recover at all if there is any outgoing data in flight, because it'll time out.
Er, no, it doesn't. Not at all. You may add a timeout at another layer (e.g. ssh often has one), but there's not one inherent for delayed data. TCP/IP's timers start to pop in when you're disconnecting (there's one typically at 120 seconds, another near 15 minutes etc.)
If it couldn't survive a 120 second holdup during data streaming it wouldn't be very useful in a lot of normal, day-to-day conditions. TCP/IP was _designed_ to survive such things. I wasn't kidding when I described my over-the-night resurrection of a data transfer.
__________________
N800/OS2007|N900/Maemo5
-- Metalayer-crawler delenda est.
-- Current state: Fed up with everything MeeGo.