On Thursday 09 April 2009 15:31:10 Daniel Senie wrote: > On Apr 9, 2009, at 7:15 AM, Robert E. Seastrom wrote: > > > > Interesting. When I got my Sprint EVDO card (u727) a year and a half > > ago, they were pretty nasty about gunning down (bidirectional spoofed > > RST coming out of the middle of the network somewhere) any TCP > > sessions that were idle for ten minutes or more. > > We observe this same kind of behavior with firewalls in the path > watching for dead sessions they can clean up. Appears they send RSTs > to both end points when they decide a session has gone away, as > that'll let end hosts figure it out sooner. Same workaround of turning > on keep=alives once a minute solves this too. The behavior in the case > of firewalls makes sense, as state tables have to be cleaned up > eventually.
The UMTS world has a lower-layer protocol called HARQ in the radio air interface which functions a little like TCP; the idea is to detect dropped packets on the radio link and retransmit them before the TCP interval times out, thus providing faster recovery. I wouldn't be surprised if there is a similar mechanism to police the use of spectrum; and a lot of mobile operators see "Internet" as an application. Somewhere around I have the incredibly long referral string Vodafone sent my blog server not long after they started real Internet service; a Squid, a Novarra, a 724 Solutions machine of some sort, and I think something else too.
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