[AusNOG] So who's read an RFC or Internet Draft?

[Geoff Huston]

> "Addresses
> 
>    Addresses are variable length strings of 4 bit chunks prefixed by a
>    length.  As address chunks are processed they are removed from their
>    position at the head of the address chunk string and placed at the
>    end of the string.  This chunk by chunk circular shifting of the
>    address allows each node in the hop by hop processing of a message
>    to examine the part of the address it consumes with out knowing how
>    much address preceeds or follows that part."
> 
> It is also interesting as there were no source address in the
> "internet protocol message”!



Yes, at one point IP played with the concept of variable length addresses,
which also appeared later in the OSI NSAP address structure, as I recall.

There is a story here I was told by Jon about the involvement of a gentleman from
Digital in the who was adamant that Digital’s equipment could not process
variable length addresses at wire speed and he pushed hard for fixed
boundaries in the packet. The compromise was 32 bits fixed size addresses.

(The same argument resurfaced in the IPv6 chained extensions header structure.
What goes around come around!)

At the _IP layer_ who needs source? I’ve forgotten who pushed for the
source to be added to the IP packet, if I ever knew, but in IPv4 the model
was that the IP information state was forward, and nothing was meant to head
backward, so the source address was unnecessary.

(You could argue that IPv6 PTB treatment is a basic violation of this 
‘forward flow’ principle, and you could well be correct!)

> So Internet addressing evolved a lot before we ended up with the IPv4
> addressing we have today. It is worth remembering that Vint Cerf, Bob
> Kahn and many others (excepting Jon Postel (RFC2468) and a few others)
> are still around, and having had the above experiences, I think the
> rest of us can be fairly confident that IPv6's 128 bit address size is
> going to be adequate.
> 


really?

http://www.potaroo.net/presentations/2005-04-19-v6.pdf


Geoff