Date: Wed, 12 Apr 2006 16:13:33 +0100 From: Brian Candler <B.Candler@pobox.com> To: fooler <fooler@skyinet.net> Cc: freebsd-net@freebsd.org, Julian Elischer <julian@elischer.org>, "M. Parsons" <mrparsons@gmail.com> Subject: Re: PPPoE question. Message-ID: <20060412151333.GA82148@uk.tiscali.com> In-Reply-To: <0f0e01c65e41$c127bd10$42764eca@ilo.skyinet.net> References: <ac8741ae0604110730g24852ba3w6c47906b9d76e911@mail.gmail.com> <443BDE05.8040204@elischer.org> <0cba01c65de0$f656f7f0$42764eca@ilo.skyinet.net> <20060412123254.GB81569@uk.tiscali.com> <0f0e01c65e41$c127bd10$42764eca@ilo.skyinet.net>
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On Wed, Apr 12, 2006 at 10:59:52PM +0800, fooler wrote: > >>set speed sync > > > >And how does that change the pppoe ethernet frames? > > nothing change and still the same... ethernet frames are at layer 2 while > synchronization (either asynchronous or synchronous) is at layer 1... > synchronous is much better than asynchronous for ethernet links... Then I think you have a misunderstanding. Ethernet frames are *always* synchronous. There are no 'start' and 'stop' bits in ethernet, only frame delimiters. The sync/async difference only has meaning for serial links (e.g. where layer 1 is RS232 / V24) PPP frames carried inside ethernet (i.e. pppoe) are therefore also carried using synchronous encoding, since ethernet is synchronous. Brian.
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