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RE: fragmentation question [7:60643] posted 01/09/2003
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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:nobody@xxxxxxxxxxxxxx]
> Sent: Wednesday, January 08, 2003 5:35 PM
> To: cisco@xxxxxxxxxxxxxx
> 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:pauldongso@xxxxxxxxxxx]
> > Sent: Wednesday, January 08, 2003 4:19 PM
> > To: cisco@xxxxxxxxxxxxxx
> > 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:
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