Date: Sun, 8 Apr 2001 22:38:59 +0200 From: J Wunsch <j@uriah.heep.sax.de> To: Martin Husemann <martin@duskware.de> Cc: freebsd-isdn@FreeBSD.org Subject: Re: PPP encapsulation Message-ID: <20010408223859.B518@uriah.heep.sax.de> In-Reply-To: <200104081101.f38B1GT00379@night-porter.duskware.de>; from martin@duskware.de on Sun, Apr 08, 2001 at 01:01:16PM %2B0200 References: <200104081101.f38B1GT00379@night-porter.duskware.de>
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As Martin Husemann wrote: > Actually the framing implemented by if_spppsubr.c is not a complete > implementation of RFC 1662 framing, it does not add the flag byte (0x7e) nor > FCS. (The FCS was my main concern.) I also wondered how this is supposed to happen, yes. Well, the flag _byte_ is only for octet stuffing (aka. running over an async line), while bit stuffing uses a flag bit sequence. My guess is that this flag sequence is already handled in hardware anyway (at least that's how i remember it from the old Z80 SIO which could do hardware HDLC). I have no idea about the FCS... The way it's done right now is what i have inherited from Sergej when i started modifying sppp(4). Since it happens to work against a good number of peers, i never thought about it. We could dump the raw ISDN data and analyze it... -- cheers, J"org .-.-. --... ...-- -.. . DL8DTL http://www.sax.de/~joerg/ NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-isdn" in the body of the message
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