Date: Tue, 01 Jun 1999 12:51:45 -0700 From: bmah@CA.Sandia.GOV (Bruce A. Mah) To: slava <sl@zeus.dnt.md> Cc: "Bruce A. Mah" <bmah@california.sandia.gov>, freebsd-questions@FreeBSD.ORG Subject: Re: [off-topic] DF bit and IP Message-ID: <199906011951.MAA04824@stennis.ca.sandia.gov> In-Reply-To: Your message of "Tue, 01 Jun 1999 12:24:50 -0000." <Pine.BSF.4.05.9906011223050.13274-100000@zeus.dnt.md>
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--==_Exmh_1854237312P Content-Type: text/plain; charset=us-ascii If memory serves me right, slava wrote: > Why is MTU 576 so popular? Is it because any device will have no less? > Can anyone explain? 576 bytes (octets, whatever) is the default MTU for TCP stacks that do not perform path MTU discovery, whenever they try to send to a destination that is not on a directly attached subnet. It's also required that any Internet host be able to reassemble a packet at least 576 bytes in length. Some people incorrectly assume that this fact implies that 576 is the minimum MTU for any IP subnet, but it's not (it's something like 68 bytes). I remember a discussion at an IETF meeting over what the minimum MTU for IPv6 should be. After much thought, it was decided that the Ethernet MTU (1500/1536) would suffice for all but two cases that anyone could think of. (The two cases were IP-over-Appletalk and a satellite network that one of the ipng working group members had architected.) Bruce. --==_Exmh_1854237312P Content-Type: application/pgp-signature -----BEGIN PGP MESSAGE----- Version: 2.6.2 iQCVAwUBN1Q50KjOOi0j7CY9AQF+sQP/fN9Bfihrlkk6VPbf7cB0lXs0eSzA3l/f /W0OsbsO6Y8LsAHmY8+fFltNwBvmA1okCXJNg0ds8jVKredO+aNoLHgnGH8nX9Kj h7LFE8AXuq8nXI0zAXDTr85Atc0/VYHQufL8tkyfjS6uT8up/xg/sAiyC/O7IPzh TANyG4/dJm8= =C1PG -----END PGP MESSAGE----- --==_Exmh_1854237312P-- To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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