Steven A. Ridder wrote: > > Thanks! I was just curious. What about L2 headers in Frame > Relay > Fragmentation (frf.12)?
They probably stay the same? The FR header doesn't have much in it, but what it does have should be in each fragment, I would think. But I'm not sure on that one. That's one we can't just look up in an RFC... Gotta run. You could repost this as a new message so others notice it!? :-) Priscilla > > > ""Priscilla Oppenheimer"" wrote in > message > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > Steven A. Ridder wrote: > > > > > > Does anyone know if a packet is fragmented, that the > specific > > > values in a > > > field are replicated across all headers of the fragmented > > > packets, or just > > > the first one? > > > > > > Meaning, if I have a packet that has IP Prec 5, and a router > > > along the way > > > has to fragment the packet, would it be so kind as to put IP > > > Prec on all the > > > headers? > > > > Yes, it should. Per RFC 791, a router (or gateway as the RFC > calls it) > > copies the contents of the header fields from the original > datagram into > the > > new headers of all the fragments. Of course, the following > fields may > > change, however: > > > > (1) options field > > (2) more fragments flag > > (3) fragment offset > > (4) internet header length field > > (5) total length field > > (6) header checksum > > > > Also, with the options field, options may or may not be > copied into each > > fragment. There's a bit that the sender can set saying > whether they must > be > > or not. But in general, all bits and bytes are copied into > each fragment > IP > > header. > > > > Prscilla > > > > > > > > Steve > > > > > > > > > ""Priscilla Oppenheimer"" wrote in > > > message > > > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > > > > Mossburg, Geoff (MAN-Corporate) wrote: > > > > > > > > > > Thanks for clearing that up; > > > > > > > > No problem. > > > > > > > > > I don't mind being told I'm > > > > > mistaken. I > > > > > recently decided that the only way I'm really going to > learn > > > > > from this group > > > > > is to take a chance on confirming what I THINK I know, > and > > > > > asking questions > > > > > about what I DON'T know. :) A lesson in humility, to be > > > sure. > > > > > > > > I know what you mean. I like to pretend to be an uber > goddess > > > of all > > > things > > > > tech, but to learn, I have to admit to lots of > cluelessness > > > in some areas. > > > > It can be a bit painful, but definitely worth it! :-) > > > > > > > > Priscilla > > > > > > > > > GM > > > > > > > > > > -----Original Message----- > > > > > From: Priscilla Oppenheimer > [mailto:[EMAIL PROTECTED]] > > > > > Sent: Wednesday, January 08, 2003 5:35 PM > > > > > To: [EMAIL PROTECTED] > > > > > Subject: RE: fragmentation question [7:60643] > > > > > > > > > > > > > > > Mossburg, Geoff (MAN-Corporate) wrote: > > > > > > > > > > > > Someone correct me if I'm wrong: > > > > > > > > > > OK, you're wrong. :-) Look it up or use a protocol > analzyer. > > > > > > > > > > > All the "fragments" have the TCP/UDP/IP headers, or > else > > > they > > > > > > can't be > > > > > > routed to their destination. > > > > > > > > > > Routing to their destination just requires the IP > header, > > > which > > > > > is in each > > > > > fragment. The TCP or UDP headers are not in the > fragments, > > > past > > > > > the first > > > > > one. The IP layer at the end device puts it all back > > > together > > > > > and hands the > > > > > packet to the TCP or UDP layer. TCP or UDP get the full > > > packet > > > > > and can > > > > > "route" it to the correct process, based on the > destination > > > > > port number. > > > > > > > > > > > "Fragmentation" is just a way of breaking up the data > > > payload > > > > > > into smaller > > > > > > > > > > Data payload from IP's point of view. > > > > > > > > > > > packets, but it puts individual headers on each > packet. > > > > > > MTU is the total size of each packet, including the > > > header. > > > > > > > > > > The term isn't always used that way, though. > > > > > > > > > > > GM > > > > > > > > > > > > -----Original Message----- > > > > > > From: Paul Dong So [mailto:[EMAIL PROTECTED]] > > > > > > Sent: Wednesday, January 08, 2003 4:19 PM > > > > > > To: [EMAIL PROTECTED] > > > > > > Subject: fragmentation question [7:60643] > > > > > > > > > > > > > > > > > > Hi All, > > > > > > > > > > > > Please shed a light on this as I am confused. > > > > > > > > > > > > Fragmentation for UDP/TCP: > > > > > > * Only the first fragment contains the UDP or TCP > > > header, not > > > > > > the > > > > > > sequencial fragments? > > > > > > > > > > > > Fragementation for IP packets > > > > > > * every fragmented packet will contains ip header? > > > > > > > > > > > > MTU 1500 bytes, doesn't it mean the data payload can > not > > > > > exceed > > > > > > 1500 > > > > > > bytes or the whole packet size(payload+header) can not > > > exceed > > > > > > 1500 > > > > > > bytes? > > > > > > > > > > > > Thanks in advance > > > > > > > > > > > > Paul > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=60979&t=60643 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
