OSI/TS Configuration and Management Manual

OSI Transport Services
OSI/TS Configuration and Management Manual—424831-001
5-10
Address Sharing
Address sharing can be implemented at various levels, as discussed in the following
subsections. Note that address sharing is not the same as multiplexing, which is
discussed later in this section.
Address Sharing for X.25 Networks
There are several levels of address sharing possible for X.25 networks, as follows:
•
Port address
For networks using the 1980 addressing standard, the port address provides the first
level of address sharing in the X.25 subnetwork. For this option, several ports
(subaddresses) are defined under the same DTE network address to allow multiple
logical addresses on the same physical line.
•
NSAP address
For networks using the 1984 addressing standard, the NSAP address provides the
first level of address sharing. For this option, several NSAPs can share the same
X.25 DTE network address (the port number is ignored).
•
TSEL
In all X.25 networks, TSELs can share the same NSAPs so that two or more
transport logical addresses can share the same network address.
Figure 5-1. Address Sharing
501CDT .CDD
TSAP Addresses
NSAP Addresses (1984)
or
Ports (X.25 Subaddresses, 1980)
X.25 DTE Address
or
LAN Station Address