Date: Sun, 21 May 2006 11:49:17 -0400 From: Bill Vermillion <bv@wjv.com> To: Mike Tancsa <mike@sentex.net> Cc: freebsd-net@freebsd.org, Ian Smith <smithi@nimnet.asn.au>, Brian Candler <B.Candler@pobox.com> Subject: Re: improving transport over lossy links ? Message-ID: <20060521154917.GB2053@wjv.com> In-Reply-To: <6.2.3.4.0.20060521104147.081af2d8@64.7.153.2> References: <6.2.3.4.0.20060519110026.05820230@64.7.153.2> <Pine.BSF.3.96.1060520014045.15967A-100000@gaia.nimnet.asn.au> <6.2.3.4.0.20060519121104.1126b480@64.7.153.2> <20060521092602.GB20262@uk.tiscali.com> <6.2.3.4.0.20060521104147.081af2d8@64.7.153.2>
next in thread | previous in thread | raw e-mail | index | archive | help
Throwing caution to the wind and speaking without thinking about what was being said on Sun, May 21, 2006 at 11:09 , Mike Tancsa blurted this: > At 05:26 AM 21/05/2006, Brian Candler wrote: > >On Fri, May 19, 2006 at 12:38:31PM -0400, Mike Tancsa wrote: > >> Thanks for the reply. Even at 28.8 I am seeing loss with > >> the connection dropping and seeing dropped packets (e.g. > >> May 19 12:04:43 soekris4801 ppp[3404]: tun0: Phase: 1: HDLC errors -> > >> FCS: 1, ADDR: 0, COMD: 0, PROTO: 0) > >If you have an error-correcting modem, but you are seeing data corruption, > >then I'd expect the data corruption is occuring on the RS232 link between > >the PC and the modem at one end or the other. You may have a handshaking > >problem (i.e. ensure the modem is configured for CTS/RTS handshaking, and > >the port is configured for this too; with pppd it's "crtscts", I don't know > >about userland ppp; and ensure the cables are wired properly) > >If your app could cope with the lack of bandwidth, forcing the modems to > >2400bps operation can make links over dodgy lines a lot more reliable. > > Hi, > Its not so much data corruption of packets on the wire, but > the modem dropping the connection, retraining and > renegotiating. When the retrains and re negotiations happen, this > can cause problems for the VPN as keep alives are missed, tx buffers > can fill up etc. I have tried a number of modems, the current one > being U.S. Robotics 56K FAX INT V5.22.70. and I am also trying an > external Intel at the office The best modems I've found are the ones from Multi-tech. Even their super-small ones. Before we added a PRI and a Livingston we were thinking about using the MT's in the 19" rack mount box they have. And when performing fax from email - using sendmail incoming and routing to fax [in the early days of the current 'net before many people had 'net connections] the MT's were the only ones that worked with virtually ever target fax machine. The MTs are external. Bill -- Bill Vermillion - bv @ wjv . com
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20060521154917.GB2053>