Date: Sun, 7 Dec 1997 19:39:32 -0800 From: John-Mark Gurney <gurney_j@efn.org> To: Brad Karp <karp@eecs.harvard.edu> Cc: pst@shockwave.com, freebsd-hackers@FreeBSD.ORG, karp@dominator.eecs.harvard.edu Subject: Re: FreeBSD Metricom driver: I wrote one in September... Message-ID: <19971207193932.61833@hydrogen.nike.efn.org> In-Reply-To: <199712080258.VAA19022@dominator.eecs.harvard.edu>; from Brad Karp on Sun, Dec 07, 1997 at 09:58:59PM -0500 References: <199712080258.VAA19022@dominator.eecs.harvard.edu>
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Brad Karp scribbled this message on Dec 7: > A friend forwarded me the thread from freebsd-hackers (to which I > don't subscribe) about a Metricom radio driver for FreeBSD: specifically, > that some are considering writing one, and that consensus was that one > didn't already exist. Not true! I'm glad your friend forwarded the message... I'm greatly interested... > My driver is written over the IP tunnel (tun), and is completely portable > (no #ifdefs, even) between FreeBSD and NetBSD (I use it on both systems). It > does neighbor discovery, dynamically handles IP-to-MAC mapping for the radios > (with no centralized ARP server, despite the non-broadcast nature of Metricom's > radios), and works very well, overall. hmmm... tun is nice for portability, but it still doesn't match the performance of a kernel land driver... the extra context switches do impact performance... a ping to a remote host has to traverse the kernel/userland boundary three times when pinging a remote host... (ping->kernel->tunnel->output to device/network)... I actually have the NetBSD kernel strip driver compiling... I just need to test the driver... > I wanted to mention this so that others might not spend time duplicating > effort I've already spent, and so that my work is known. I hadn't placed > an emphasis on getting the code widely distributed so far because I'm more > interested in getting routing research results that use my driver as a > substrate. personally, I think this goes along with the argument with the pppd/iij-ppp... each have their advantages (with a friend, I've gotten two EXTERNAL 28.8k modems down to 107ms rtt for 64byte ping using pppd on both ends... compared to external isdn ta's that I've heard get around 40ms, it's not bad.. :) > I can provide the code to interested parties, and would certainly be very happy > to see it distributed as part of FreeBSD, if there is interest and someone with > sufficient authority to fold it in invites me to contribute it. I'd be willing to test and commit the driver, assuming no other commiters object.. :) also, I assume that the license for the driver is similar to the BSD license? and not GPL'd? > Again, as I don't subscribe to freebsd-hackers, please address comments, > questions, and/or requests for the code to me by email. ok, I'm adding you to my aliases... ttyl.. -- John-Mark Gurney Modem/FAX: +1 541 683 6954 Cu Networking Live in Peace, destroy Micro$oft, support free software, run FreeBSD
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