Verizon EVDO issues

Thu Apr 9 16:06:29 UTC 2009

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.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 194 bytes
Desc: This is a digitally signed message part.
URL: <http://mailman.nanog.org/pipermail/nanog/attachments/20090409/803a795e/attachment.sig>