All things related to multicast

["Charles R. Anderson" <>]

On Mon, May 19, 2003 at 12:19:14PM -0700, Tom Pusateri wrote:
pusateri> That's the checksum in the PIM header of the register message,
pusateri> not the dummy ip header following the PIM header.
pusateri> You're confusing the headers.

No, I'm not.

Yes, the PIM header must be correct (to several definitions of
"correct", the older one which says the checksum is taken over the
entire packet, and the newer one which says the checksum is taken over
the first 8 bytes, i.e. just the PIM header.)

As I recently discovered during interop testing, the Encapsulated IP
packet's IP Header Checksum must also be correct.  The Juniper drops
Null-Registers (and probably regular Registers) and increments the "Bad
Checksum" counter under "show pim statistics" if it receives one with a
bad checksum here.

-- 
Charles R. Anderson
Network Engineer
Computing and Communications Center
Worcester Polytechnic Institute