Date: Tue, 21 Apr 1998 18:52:06 -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.3.91.980421184639.15079B-100000@heathers2.stdio.com> In-Reply-To: <199804212242.PAA00550@grumpy.ccnvhi.com>
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On Tue, 21 Apr 1998, Paul Norton wrote: > Larry S. Lile writes: > > 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: > > 1492 is the MTU for Ethernet II(??), I believe, but I'd have to go > back and reference Stevens to be sure. Are you in a bridged environment? > > > #define ISO88025_TYPE_LEN 2 /* Assumed */ > > #define ISO88025_CRC_LEN 4 /* Assumed */ > > You'll never see the TR MAC CRC. It is stripped from the frame before > the driver gets it. So we should dump it. > > #define ISO88025_HDR_LEN (ISO88025_ADDR_LEN*2+ISO88025_LEN) /* +RIF? */ > > #define ISO88025_MIN_LEN x /* No clue */ > > 802.5 can have a zero-length payload. So ISO88025_MIN_LEN = ISO88025_HDR_LEN How much space for the source routes? > > #define ISO88025_MAX_LEN 1518 /* Assumed same as ethernet */ > > 17,960 for total frame size at 16 Mbps. #define ISO88025_MAX_LEN 17960 > > #define ISO88025_IS_VALID_LEN(foo) \ > > ((foo) >= ISO88025_MIN_LEN && (foo) <= ISO88025_MAX_LEN) > > This should be determined by the driver after initialization. If the > adapter has 8K shared-RAM configured, you'll only be able to support > about a 3K MTU. If they have 64K configured the MTU can go to 17K. At > any rate you will only be able to determine this after the driver/adapter > has initialized. This would still be valid because we are really looking at absolute maximums and minimums. Each driver could reject packets based on its current configured MTU. Larry lile@stdio.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-tokenring" in the body of the message
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