"Steven M. Bellovin" <s...@cs.columbia.edu> writes: > On Thu, 09 Apr 2009 07:15:44 -0400 > "Robert E. Seastrom" <r...@seastrom.com> wrote: > >> >> Seth Mattinen <se...@rollernet.us> writes: >> >> > I have a few Sprint EVDO cards. They go into standby when nothing is >> > actively going on and fire up within seconds when there is >> > something to do. I regularly use everything from SSH to streaming >> > video without any issues. I only notice the delay with SSH when I >> > don't type anything for a few minutes and it has to come active >> > again, but I can leave it idle for hours and it never drops. >> >> 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. Quite repeatable and >> verified on the downlow by People With Insight that this was in fact >> expected behavior from boxes that were in the middle of the network >> due to "politics" (unlike Verizon, Sprint appears to put no >> restrictions on inbound connections to the evdo-host). Putting this: >> >> ServerAliveInterval 60 >> >> in ~/.ssh/config was an effective work-around. I have not revisited >> the issue to see if Sprint has corrected this behavior. Perhaps >> budget constraints or customer complaints have caused Sprint to >> revisit the necessity of having extraneous hardware in their network. > > I use a Verizon Wireless u727; before that, I used a PCMCIA card. I've > never had problems with drops on idle. *However* -- if there was a > packet from the wrong IP address, the older card would drop the > connection -- apparently, that behavior was required by the spec. (I > haven't checked if the newer one will do that.) So, if the > EVDO connection dropped while I had, say, an IMAP or ssh session open, > and I dialed back in, the next TCP packet would cause EVDO to drop > again... I finally "fixed" it by creating ipfilter rules in my ppp-up > script to block all "bad" packets from going out.
Interesting. I never had that behavior exhibited on my old PCMCIA card on Verizon or on my u727 on Sprint. What OS platform were you on lappie-wise? I've thought on a couple of occasions that a "geek bake-off" between EVDO and 3G providers looking for technical jack moves on the providers' part would make for a nice NANOG lightning talk. Sadly, I haven't the time to devote to such an endeavor. -r
