Date: Sat, 9 Aug 1997 13:15:27 -0700 (PDT) From: Tom Samplonius <tom@sdf.com> To: "Jamil J. Weatherbee" <jamil@counterintelligence.ml.org> Cc: Peter Korsten <peter@grendel.IAEhv.nl>, hackers@freebsd.org Subject: Re: ISDN drivers/cards Message-ID: <Pine.BSF.3.95q.970809130550.3841A-100000@misery.sdf.com> In-Reply-To: <Pine.BSF.3.96.970809110647.7721B-100000@counterintelligence.ml.org>
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On Sat, 9 Aug 1997, Jamil J. Weatherbee wrote: > going from TA to TA or TA to Router, I'd love to see an internal card that > doesn't use 16550's that I can put in my freebsd machine and get good This can be improved a lot. Most TAs support a 230400bps rate, but FreeBSD does not. Doubling the TA input rate will certainly have a positive effect on latency. FreeBSD-current now detects the 16670 UART that supports 230400 (and faster. But it doesn't seem possible to set a port to 230400. BTW, it isn't even possible to use full ISDN with at 115200 bps. Basically if you drive ISDN at 115200, you will get rates of about 10KB/s, but if you could the entire ISDN line you will get 15KB/s. This is mainly due to the extra overhead of async versus sync serial (well, sync serial carries the "overhead" out of band). BTW, I use an 3COM Impact II extrernal ISDN TA. It works very well, except that I'd like to drive it at 230400. At 115200 bps, I get round-trip times of 80ms. I'm not sure where you are getting your 100ms times from, except it could be from a poorly performing TA (ie. old Bitsurfer), or Win95 (whose PPP performance is terrible, and adds a lot of packet processing latency). Tom
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