> Some of the terms related to Ethernet should be clarified, I believe. > The IEEE 802.3 standard does not recognize the terms 'jumbo' or > 'superjumbo'. These are as you point out of the standard. The max frame > size in the original Ethernet standard was 1518. This was slightly > increased about a decade ago to 1522 when IEEE 802.1 added four bytes > for VLAN ID. More recently the IEEE 802.3as extended the max size of the > Ethernet frame to 2048.
The 1518 would be (14 header + 1500 ULP + 4 trailing CRC). Focusing only on the ULP, can we say that 1500 bytes is the nominal MTU of today's Internet, and therefore all attached devices SHOULD configure a minMRU of 1500? Then, can we also say that applications that send packets larger than 1500 bytes (with DF=1) are RECOMMENDED to use RFC4821? Finally, could we also say that tunnel decapsulators SHOULD configure a minMRU of 2048 to account for encapsulations that might extend a 1500 byte ULP out to the IEEE 802.as maximum frame size? Asked another way, can all of this be addressed in a brief BCP that captures something like the above? Thanks - Fred [EMAIL PROTECTED] > Also, there is no such thing as a 'extra large > Ethernet header'. The header of an Ethernet frame is of fixed size. It > is the payload in the Ethernet frame that may be of variable length. > > Dan > > > > > > > -----Original Message----- > > From: Matt Mathis [mailto:[EMAIL PROTECTED] > > Sent: Wednesday, August 01, 2007 5:35 PM > > To: Internet Area > > Subject: Re: [Int-area] What is a jumbogram, was: Larger MTUs > > > > Jumbo just means larger than standard. Given that there are > > so many standards to choose from... well you get the idea. > > > > To add to the confusion, to IEEE 802.3, jumbo means 1536 (I > > think I got the number right). This is for extra large > > Ethernet headers with a 1500 byte payload. They use > > "superjumbo" to refer to 9kB, etc. > > > > It is really important that we do not standardize 9k or any > > other fixed MTU as the new Internet cell size. The intent of > > 4821 was to permit the Internet to support diverse MTUs at > > all scales. With a couple of additional clicks on Moore's > > Law 9k is likely to be deemed too small, but we really don't > > want to have to do any part of this over again. > > > > BTW for some background on the wider problem check out > > http://www.psc.edu/~mathis/MTU > > > > THanks, > > --MM-- > > ------------------------------------------- > > Matt Mathis http://www.psc.edu/~mathis > > Work:412.268.3319 Home/Cell:412.654.7529 > > ------------------------------------------- > > Evil is defined by mortals who think they know "The Truth" > > and use force to apply it to others. > > > > > > > > _______________________________________________ > > Int-area mailing list > > [email protected] > > https://www1.ietf.org/mailman/listinfo/int-area > > > > > _______________________________________________ > Int-area mailing list > [email protected] > https://www1.ietf.org/mailman/listinfo/int-area > _______________________________________________ Int-area mailing list [email protected] https://www1.ietf.org/mailman/listinfo/int-area
