This parameter value determines the maximum size of
a Routing message. It therefore determines the maximum
size message that can be forwarded. This size includes
protocol overhead down to and including the End
Communication layer, plus a constant value of 6. (This
value of 6 is included to provide compatibility with
the parameter definition in Phase III, which included
the Routing overhead.) It does not include Routing or
Data link overhead (except for the constant value of
6). There is one buffer size for all circuits.
NOTE: The BUFFER SIZE defines the maximum size messages
that the Routing layer can forward. The SEGMENT BUFFER
SIZE (defined below) defines the maximum size messages
that the End Communication layer can transmit or
receive. The SEGMENT BUFFER SIZE is always less than
or equal to the BUFFER SIZE. Normally the two
parameters will be equal. They may be different to
allow the network manager to alter buffer sizes
on all nodes without interruption of service. They both
include an extra 6 bytes for compatibility with Phase
III.