[113258] in North American Network Operators' Group
Verizon EVDO issues
daemon@ATHENA.MIT.EDU (Alexander Harrowell)
Thu Apr 9 12:08:43 2009
From: Alexander Harrowell <a.harrowell@gmail.com>
To: NANOG list <nanog@nanog.org>
Date: Thu, 9 Apr 2009 17:06:29 +0100
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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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=3Dalives 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=20
interface which functions a little like TCP; the idea is to detect dropped=
=20
packets on the radio link and retransmit them before the TCP interval times=
=20
out, thus providing faster recovery. I wouldn't be surprised if there is a=
=20
similar mechanism to police the use of spectrum; and a lot of mobile operat=
ors=20
see "Internet" as an application. Somewhere around I have the incredibly lo=
ng=20
referral string Vodafone sent my blog server not long after they started re=
al=20
Internet service; a Squid, a Novarra, a 724 Solutions machine of some sort,=
=20
and I think something else too.
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