Date: Tue, 10 Aug 2004 12:06:01 +0100 From: Doug Rabson <dfr@nlsystems.com> To: Alexander Nedotsukov <bland@FreeBSD.org> Cc: freebsd-firewire@FreeBSD.org Subject: Re: max MTU for fwip device. Message-ID: <1092135961.13089.2.camel@builder02.qubesoft.com> In-Reply-To: <4118A46B.9030901@FreeBSD.org> References: <4116EA33.8040405@FreeBSD.org> <411843FD.4090201@FreeBSD.org><41189199.5020201@FreeBSD.org> <1092133653.13089.0.camel@builder02.qubesoft.com> <4118A46B.9030901@FreeBSD.org>
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On Tue, 2004-08-10 at 11:33, Alexander Nedotsukov wrote: > >>>Interesting. The specification for IPv6 on firewire is clearer: > >>> > >>> The default MTU size for IPv6 packets on an IEEE1394 network is 1500 > >>> octets. This size may be reduced by a Router Advertisement [DISC] > >>> containing an MTU option which specifies a smaller MTU, or by manual > >>> configuration of each node. If a Router Advertisement received on an > >>> IEEE1394 interface has an MTU option specifying an MTU larger than > >>> 1500, or larger than a manually configured value, that MTU option may > >>> be logged to system management but MUST be otherwise ignored. The > >>> mechanism to extend MTU size between particular two nodes is for > >>> further study. > >>> > >>> > >>> > >>> > >>Mmm. I still do not see any prohibition of MTU size > 1500. What I see > >>here is definition of automatic MTU adjustment. It's stated that ATM MTU > >>size may be only reduced by such mechanism. Am I right? > >>So manual configuration of interface for MTU size > 1500 violates nothing. > >> > >> > > > >Of course - I certainly don't want to stop people from configuring an > >MTU size > 1500. I just think that for the compiled in default, we > >should go with the spec for now. > > > > > > > I do not object default MTU either. But the problem is we have hardcoded > 1500 limit in SIOCSIFMTU ioctl handler ATM. Check sys/net/if_fwsubr.c ;-) Oops - I'll fix that when I get a chance. I've been side-tracked recently trying to finish off the TLS stuff.
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