Re: Review comments on draft-ietf-shim6-proto-03.txt

[Erik Nordmark <erik.nordmark@sun.com>]

Geoff Huston wrote:
> In response to your query (and Erik can correct me if I'm wrong) It is 
> my understanding in the specification that whenever the ULID pair is 
> used as the locator pair then the SHIM6 extension header (the context 
> value) is omitted from the packet. This allies to the initial contact 
> pahse, and also in any subsequent time when the SHIM selects the ULID 
> pair as the current locator pair.

Correct. But folks have also suggested that we should allow the shim6 
extension header all the time i.e., even if the receiver doesn't have to 
rewrite the locators. I don't see any harm in allowing this for folks 
that want their packets to be bigger...

> i.e. it is my understanding that the packet header is simply an implicit 
> "please perform an address substitution" instruction to the other end, 
> and the locator pair plus the context value identifies the particular 
> substitution to a ULID pair that the remote end should perform. If the 
> locators are the ULID then no substitution is necessary, and no 
> extension header is necessary.
>
> At least thats the way I interpret the specification, and I was 
> wondering if this should be explicitly stated in the spec.

If we allow the above, it is really "please lookup the context state and 
check if you need to replace the locators", but since replacing the 
locator pair with the identical locator pair can be still viewed as a 
replacement, that's just a detail.

Any ideas where such text would best belong in the specification?

   Erik