North American Network Operators Group

Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical

Re: PMTU-D: remember, your load balancer is broken

  • From: Paul Vixie
  • Date: Sat Jun 17 15:04:28 2000

[email protected] writes:

> Has this changed?  Has "fragmentation" become a Great Evil, ... ?

Yes.  http://research.compaq.com/wrl/techreports/abstracts/87.3.html says:

                              Research Report 87/3, December 1987 

                              87.3 -- Fragmentation Considered Harmful 

                              Christopher A. Kent, Jeffrey C. Mogul 

                                 PostScript Version 
                                 gzipped PostScript Version 
                                 Adobe Acrobat PDF Version 

                              Internetworks can be built from many
                              different kinds of networks, with varying
                              limits on maximum packet size. Throughput is
                              usually maximized when the largest possible
                              packet is sent; unfortunately, some routes
                              can carry only very small packets. The IP
                              protocol allows a gateway to fragment a
                              packet if it is too large to be transmitted.
                              Fragmentation is at best a necessary evil; it
                              can lead to poor performance or complete
                              communication failure. There are a variety of
                              ways to reduce the likelihood of
                              fragmentation; some can be incorporated into
                              existing IP implementations without changes
                              in protocol specifications. Others require
                              new protocols, or modifications to existing
                              protocols.

                              [email protected]
                              Copyright  2000 Compaq Computer Corporation 

I was there, I saw the research that went into this, I know the guys who
did the work, and I agree completely with the conclusions thus presented.