TCP/IP Configuration and Management Manual

TCP/IP Configuration and Management Manual—427132-004
F-1
F
NonStop Systems Used as Internet
Gateways
Although networks in the Internet are normally connected to each other by
industry-standard routers, these networks can be connected by devices called
gateways. A gateway is a special-purpose, dedicated computer that attaches to two or
more networks and routes packets from one to the other. Gateways route packets to
other gateways until the packets can be delivered to the final destination directly
across one physical network. An HP NonStop system can function as a gateway.
Figure F-1
shows the relationship between hosts and gateways in the Internet. (A
gateway is often a host as well, but not all hosts are gateways.) The Internet addresses
shown for the networks and hosts are represented externally as a.b.c.d, where a, b, c,
and d are the values of the four octets (
a being the most significant octet).
In this figure two networks, NETA and NETB, are connected by means of a gateway,
HOST4. The three machines labelled HOST1, HOST2, and HOST3 belong to NETA.
The seven machines labelled HOST6, HOST7, HOST8, HOST9, HOST10, HOST11,
and HOST12 belong to NETB. The gateway, HOST4, belongs to both networks, NETA
and NETB.
Figure F-1. Hosts and a Gateway in an Internet
018VST .VSD
HOST4
98.0.1.6
37.0.4.1
Network NETA
Internet
Address
= 98.0.0.0
HOST3
98.0.7.4
Network NETB
Internet
Address
= 37.0.0.0
HOST7
37.0.3.9
HOST8
37.0.3.2
HOST6
37.0.8.1
HOST2
98.0.3.1
HOST11
37.2.2.9
HOST10
37.1.3.5
HOST9
37.1.0.8
HOST12
37.2.8.1
HOST1
98.0.2.9
Gateway