On Thu, Aug 16, 2007 at 07:18:47AM +0930, Mark Smith wrote:
> I'm don't think I'm going down it. You seemed to be questioning why
> subnets were fixed length, I provided most likelyreasons why, including
> evidence that the original design of IPv4, pre-classes, also followed
> this model. I think that shows that when there is the opportunity to
> have fixed length node addressing it is very desirable, and has been
> chosen by many protocol designers (DECNET Phase IV has it too, IIRC)
Historical remark: To a certain degree.
Area addresses have a fixed size (6 bits), and node addresses within an
area also have a fixed size (10 bits). But Areas are not bound to a
LAN. All host addressing on a link is done via sort of neighbour
discovery (using hello packets). Areas are used for (I think) IS-IS- or
OSPF-like two-level routing, but could consist of any number of LANs
and point to point links.
(Ethernet LAN addresses were created by concatenating the full DECnet
address (16 bits) and DEC's prefix AA-00-04-00-.)
-is
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