HP-UX LAN Administrator's Guide (Feburary 2007)

DRAFT COPY Network Addressing
Configuring Gateways on Variable-Length Subnets
Chapter 7 129
Configuring Gateways on Variable-Length Subnets
Besides using the appropriate subnet masks, each gateway needs to be configured so that it
can properly route messages among the several subnet works. Following are descriptions of
two types of routing: explicit routing and dynamic routing. When using explicit routing, you
must specify the IP address of each gateway to which you are directly connected. When using
dynamic routing, you need to specify only the IP address of one gateway, and the system
learns the IP address of other gateways from the specified gateway.
Explicit Routing
There are many ways to set up routing. For example, you might add the following entries to
the netconf file on Host A in Figure 7-14:
ROUTE_DESTINATION[0]=”net 192.6.12.192”
ROUTE_MASK[0]=”255.255.255.224”
ROUTE_GATEWAY[0]=”192.6.12.130”
ROUTE_COUNT[0]=”1”
ROUTE_DESTINATION[1]=”net 192.6.12.33”
ROUTE_MASK[1]=”255.255.255.240“
ROUTE_GATEWAY[1]=”192.6.12.131”
ROUTE_COUNT[1]=”1”
ROUTE_DESTINATION[2]=”net default”
ROUTE_MASK[2]=””
ROUTE_GATEWAY[2]=”192.6.12.132”
ROUTE_COUNT[2]=”1”
The 1 in each ROUTE_COUNT entry specifies an indirect route. For example, messages for
the system on the 192.6.12.32 subnetwork will first be sent to Host B (192.6.12.131), and from
there they will be forwarded to the destination system.
Dynamic Routing
Alternatively, and perhaps the easiest way to manage growth on the 192.6.12 network, you
might add the following entries to each netconf file.
Hosts A, B and C:
ROUTE_DESTINATION[0]=”default”
ROUTE_GATEWAY[0]=”192.6.12.132”
ROUTE_COUNT[0]=”1”
Host D (Site gateway):