[tcpm] About the urgent pointer...

[David Borman <david.borman at windriver.com>]

Hello,

One of the items on the TCPM agenda for IETF 74 is the TCP Urgent  
pointer.  I want this to be a very focused discussion around one  
question:  Should the urgent pointer point to the last byte of urgent  
data, or the first byte of non-urgent data?

RFC 793 has one place (p. 17) where it says that it is the first byte  
of non-urgent data, and at least two places (p. 41 and p. 56) where it  
says that it is the last byte of urgent data.  Though RFC 961 and RFC  
1122 resolve this ambiguity and are clear that the urgent pointer is  
defined to point to the last byte of urgent data, as draft-gont-tcpm- 
urgent-data-01 points out most systems actually implement it as the  
first byte of non-urgent data.  This goes back to the original BSD  
code from CSRG.

So, the question is *not* what do the RFCs say, because they are  
clear.  The question is, what do we do about the mismatch between what  
the RFCs say, and what is generally implemented?

			-David Borman