Computation of the Internet Checksum via Incremental Update
RFC 1624

7.  Acknowledgments

   The contribution of the following individuals to the work that led to
   this document is acknowledged:

          Manu Kaycee - Ascom Timeplex, Incorporated
          Paul Koning - Digital Equipment Corporation
          Tracy Mallory - 3Com Corporation
          Krishna Narayanaswamy - Digital Equipment Corporation
          Atul Pandya - Digital Equipment Corporation

   The failure condition was uncovered as a result of IP testing on a
   product which implemented the RFC 1141 algorithm.  It was analyzed,
   and the updated algorithm devised.  This algorithm was also verified
   using simulation.  It was also shown that the failure condition
   disappears if the checksum verification is done as per RFC 1071.

8.  Security Considerations

   Security issues are not discussed in this memo.

9.  Conclusions

   It is recommended that either [Eqn. 3] or [Eqn. 4] be the
   implementation technique used for incremental update of the standard
   Internet checksum.

10.  Author's Address

   Anil Rijsinghani
   Digital Equipment Corporation
   550 King St
   Littleton, MA 01460

   Phone: (508) 486-6786
   EMail: anil@levers.enet.dec.com

Rijsinghani                                                     [Page 5]
RFC 1624             Incremental Internet Checksum              May 1994

11.  References

   [1] Postel, J., "Internet Protocol - DARPA Internet Program Protocol
       Specification", STD 5, RFC 791, DARPA, September 1981.

   [2] Braden, R., Borman, D., and C. Partridge, "Computing the Internet
       Checksum", RFC 1071, ISI, Cray Research, BBN Laboratories,
       September 1988.

   [3] Mallory, T., and A. Kullberg, "Incremental Updating of the
       Internet Checksum", RFC 1141, BBN Communications, January 1990.

   [4] Thornton, J., "Design of a Computer -- the Control
       Data 6600", Scott, Foresman and Company, 1970.

Rijsinghani                                                     [Page 6]