OSI/AS and OSI/TS Supplement (Includes RFC-1006 Support)

Introduction to the Tandem TCP/IP Subsystem
Introduction to RFC-1006
107751 Tandem Computers Incorporated 1–11
Figure 1-8. Subnetworks
100
HOST4
98.0.1.6
37.0.4.1
Network NETA
Internet Address
= 98.0.0.0
Network NETB
Internet Address
= 37.0.0.0
HOST7
37.0.3.9
HOST8
37.0.3.2
37.2.0.1
HOST6
37.0.8.1
37.1.0.1
HOST2
98.0.3.1
Subnet NETD
Internet Address
= 37.2.0.0
HOST12
37.2.8.1
HOST11
37.2.2.9
HOST1
98.0.2.9
Gateway
Gateway
HOST9
37.1.0.8
HOST10
37.1.3.5
Subnet NETC
Internet Address
= 37.1.0.0
Gateway
HOST3
98.0.7.4
Tandem TCP/IP Internet Concepts
Usually a host has only one Internet address on each network it is attached to.
Because of the multiprocessing nature of the Tandem NonStop system and the fact
that more than one TCP/IP process can exist on a system, a Tandem system can
appear to the outside world as more than one logical host on a network. Multiple
TCP/IP processes in a system on the same network must be represented by multiple
Internet addresses; this way, they will appear to the network as multiple hosts.
Ports and Sockets
Ports provide a multiplexing capability by allowing multiple applications to
communicate concurrently with the same TCP/IP process. In this sense, a port
number is similar to a service access point (SAP) in OSI.
As mentioned earlier, the TCP/IP subsystem components interface with the TCP/IP
process through the sockets interface (see Figure 1-6). A socket identifies an endpoint
communications process.