TCP/IP (Parallel Library) Configuration and Management Manual

Configuring Parallel Library TCP/IP for Complex and
Heavy-Use Environments
HP NonStop TCP/IP (Parallel Library) Configuration and Management Manual—522271-006
3-27
Example for Two Gateways — Standard Listening
Model
LOOPBACK
When the monitors are started, a subnet named LOOP0 is added automatically. This
subnet provides loopback capability without requiring the use of the TCP/IP network.
When this LOOP0 subnet is created, it has an address of 0.0.0.0 in dotted decimal
form. You must change this address; use the command:
ALTER SUBNET LOOP0, IPADDRESS 127.1
The address 127.1 (or 127.0.0.1) is the standard for loopback operation.
Routes
A route is added to direct traffic destined for the 128 subnet through Gateway 1.
Another route is added to direct all other traffic through Gateway 2. The ROUTE
objects must be added to all monitors. (See ADD ROUTE Command for TCPMAN on
page 5-18.)
Subnet Mask
The subnet mask causes the first three octets to be used for determining the correct
network.
Gateway
In this example, there are potentially two destination networks to which HOST could
communicate and thus, two routes, one for each destination network. Notice that in this
case, the gateway address is the same for each route. As shown in Figure 3-11, HOST
must route a datagram destined to the other network through GTWY1, which has the
IP address of 150.50.130.1. This method is especially useful when you have multiple
gateways to multiple networks. When all the routing is through a single gateway,
however, there is a simpler way to set up your routing.
Default routing establishes a single route as the default route. This action is particularly
useful when you know that most of your TCP/IP traffic is going through a single
gateway. The second route added in Example 3-8 implements default routing. The use
of 0.0.0.0 to designate the destination network IP address is what indicates that this is
a default route. You can add more routes for those networks which cannot be reached
by using the default route.