Subject: [Int-area] new IPv4 ID update draft - 01

From: Joe Touch <[email-masked]>
Date: Fri, 22 Oct 2010 15:30:59 -0700

Hi, all,

An update to this doc has been posted, and should be announced on this 
list shortly.

Here is a summary of the changes:

- completely revised the text to focus on the key changes

	- removed the part about 'expected reordering interval';
	left as "one MSL"

	- removed "DF=1 as a SHOULD" in general
		revised to state sources should either
		send atomic packets OR rate limit non-atomic ones

	- simplified the requirements

	- reorganized to separate requirements changes,
	requirements not changed, and datagram use

The current requirements are, in brief summary:

Core:
1- ID not to be used except for reassembly
2- source MAY set ID arbitrarily for atomic datagrams
3- receiver MUST ignore ID on atomic datagrams

Corollary:
4- ID MUST NOT be reused for retransmission of non-atomic datagrams
5- overlapping fragments MUST be ignored
6- ID of unprotected (non IPsec AH or equivalent) atomic datagrams
	MAY change in transit (others MUST NOT)

Unchanged (stated because not in 2119 language in orig docs):
7- IDs of nonatomic datagrams MUST NOT repeat
	within one MSL for a given src/dst/protocol
8- DF=1 MUST NOT be fragmented
9- DF=1 MUST NOT be cleared (i.e., set to DF=0)

Recommended use:
10- non-atomic datagram sources MUST rate limit (to ensure #7)
11- upper-layer protocols SHOULD verify the integrity of datagrams
	(might want to limited this to non-atomic datagrams?)
12- sources of non-atomic datagrams using strong integrity checks
	MAY reuse the ID within one MSL
13- NATs MUST follow all these rules as if they were IP sources

Joe