Re: Class A Logical Host Addressing


Andy Malis (malis@MACARTHUR.BBN.COM)
Mon, 19 Sep 88 12:21:41 -0400


Barry,

As I believe Mike St. Johns mentioned a in an earlier message,
the PSN's logical addressing capabilities are not currently in
use by the DDN due to required changes to AHIP (1822) host
software. A possible future PSN development will be to make
logical addressing transparent for AHIP hosts as well as X.25
hosts.

To answer your second question, the criterion used by the PSNs to
choose between multiple available physical mappings for a logical
address is configurable by the network administration on a per-
logical-address basis. Three alternative criteria are available:
ordered list, closest (via delay-based network routing), and load
leveling (successive Call Requests are distributed through the
list of currently available physical mappings in a round-robin
manner).

In the previous paragraph, "available" means the destination host
port is up and the logical-address-to-physical-port mapping has
been enabled, either explicitly by the host or automatically by
the network when the host last restarted. Automatic enabling is
itself configurable by the network administration on a per-host-
port basis.

Regards,
Andy Malis
BBNCC PSN Development



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