Re: [Linux-decnet-user] Patch to 2.4.15-pre5 to fix local port alloc bug

[Paul K. <pk...@eq...>]

Excerpt of message (sent 18 November 2001) by Steven Whitehouse:
> ...
> Also, please note that this code 
> limits the maximum number of DECnet sockets (system wide) to 0xffff - 1. There 
> isn't really any need for this limit because if you take the local and remote 
> DECnet addresses into account during socket demultiplexing then you should be 
> able to have 0xffff - 1 connections to each remote node.

The global limit is typical of DECnet implementations.  The connection
identifying approach used in NSP (two identifiers, each picked by one
endpoint) was chosen specifically so each end could simply use that
identifier as an index into a vector of connection pointers.  (More
commonly, some of the bits are index and the rest are a serial number,
to distinguish old connections from new ones -- so NSP doesn't need
the TIME_WAIT state as TCP does.)  The result is (a) very easy
connection lookup for inbound traffic, (b) a global limit on
connections rather than a per remote host limit.  For the era when
DECnet (phase 2, actually) was designed, that was a fine tradeoff, and
it wasn't revisited either for phase 3 or phase 4.

     paul