I have found most/all modern 3g networks can achieve optimal download speed within their latency limitations (<200ms domestic end-to-end is normal for most today) when combined with a modern operating system that does automatic TCP receive window adjustments based on per-flow characteristics. I never had a problem getting ~2 megabit from EVDO-revA, and can get ~20 megabit without issue from the new Verizon LTE network. (Windows XP is not modern).
As for VSAT, most every vsat equipment manufacturer has TCP acceleration/proxy support built into the satellite modem. They basically forge acks at the hub site to buffer data from the server, then deliver it it to the remote end in a continuous flow. Many also have protocol optimizations for some of the more "chatty" protocols. If you use it, your 10 megabit should be achievable for typical HTTP/FTP consumer internet activities, and it's surprisingly fast. I've sustained 6 without issue on VSAT, only limited by bandwidth available, doing a simple SCP file transfer. Of course, none of this is to the scale of transatlantic gigabit transfers with a single flow... On Tue, Jun 28, 2011 at 10:16 AM, Cameron Byrne <cb.li...@gmail.com> wrote: > On Tue, Jun 28, 2011 at 9:11 AM, Leigh Porter > <leigh.por...@ukbroadband.com> wrote: > > > > > >> -----Original Message----- > >> From: Cameron Byrne [mailto:cb.li...@gmail.com] > >> Sent: 28 June 2011 16:53 > >> To: Leigh Porter > >> Cc: Andreas Ott; Eugen Leitl; williamejs...@googlemail.com; NANOG list > >> Subject: Re: [pfSense Support] Strange TCP connection behavior 2.0 RC2 > >> (+3) > >> In the 3G world, i have had good results overcoming longish RTT by > >> using the Hybla TCP algorithm http://hybla.deis.unibo.it/ > >> > >> I am hoping it gets more default traction, especially in wireless > >> where the radio link is a pretty big latency source > >> > >> Cameron > > > > How do you implement this for lots of clients and servers that have out > of the box implementations? The FastSoft box is a TCP man-in-the-middle box > that essentially implements the FAST TCP algorithm without either end having > to worry about it. > > > > You don't, the full benefits only come with a Linux kernel patch. The > good news is that it only has to be implemented on the client end. > > > I have also used home-fudged TCP proxies with some success. > > > > Some 3G/wireless/VSAT vendors implement their own TCP modification stacks > but they usually only fiddle with window sizes and such. > > > > That's why i said i hope it catches on as default :) If Android > implemented Hybla, i think it would be a great improvement for user > experience. Nobody likes the middleboxes that proxy TCP.... they cost > money, don't scale well, and are generally fragile. Hybla is not a > solution for the OPs issue, just a solution for high RTT links where > the client can do Hybla. It an evolutionary step that i think would > make a great fit in smartphones like Android. > > Cameron > > -- > > Leigh > > > > > > ______________________________________________________________________ > > This email has been scanned by the MessageLabs Email Security System. > > For more information please visit http://www.messagelabs.com/email > > ______________________________________________________________________ > > > >
