Date: Tue, 21 Apr 1998 18:15:18 -0400 (EDT) From: "Larry S. Lile" <lile@stdio.com> To: Paul Norton <pnorton@ccnvhi.com> Cc: tokenring@FreeBSD.ORG Subject: Re: Current work... Message-ID: <Pine.SUN.3.91.980421175810.15079A-100000@heathers2.stdio.com> In-Reply-To: <199804212055.NAA01835@grumpy.ccnvhi.com>
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On Tue, 21 Apr 1998, Paul Norton wrote:
> Matthew N. Dodd writes:
> > We need to set our min and max based on line speed and let the user adjust
> > to some value between if they desire. Min will probably be the same for
> > both.
>
> Max MTU is a function of ring speed and configured shared-RAM for the 16/4
> adapters. There's a draft IETF standard that recommends 1500 as
> default.
>
> > Also remember that all our data rides around in 802.2 packets so we have
> > those headers to deal with as well.
>
> Max IP MTU = Recv. buf size - 802.5 MAC header including max possible RIF
> - 802.2 header - SNAP header.
>
All the AIX boxen I admin run a MTU of 1492 on their token ring interfaces,
any clue at to the 8 byte diff? Were basically going to need a
/usr/src/sys/net/iso88025.h which would contain:
#define ISO88025_ADDR_LEN 6
#define ISO88025_TYPE_LEN 2 /* Assumed */
#define ISO88025_CRC_LEN 4 /* Assumed */
#define ISO88025_HDR_LEN (ISO88025_ADDR_LEN*2+ISO88025_LEN) /* +RIF? */
#define ISO88025_MIN_LEN x /* No clue */
#define ISO88025_MAX_LEN 1518 /* Assumed same as ethernet */
#define ISO88025_IS_VALID_LEN(foo) \
((foo) >= ISO88025_MIN_LEN && (foo) <= ISO88025_MAX_LEN)
/* This may be over-kill ? */
struct iso88025_header {
u_char iso88025_dhost[ISO88025_ADDR_LEN];
u_char iso88025_shost[ISO88025_ADDR_LEN];
u_short ether_type;
/* RIF? */
};
struct iso88025_addr {
u_char octet[ISO88025_ADDR_LEN];
};
Any ideas, suggestions or correct numbers to fill in? or should we
just kludge through the ether subsystem?
Larry
lile@stdio.com
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