Installing and Administering Internet Services

Chapter 8 331

Conﬁguring gated

Conﬁguring the RIP Protocol

RIP uses hopcount to determine the shortest path to a destination.

Hopcount is the number of routers a packet must pass through to reach

its destination. If a path is directly connected, it has the lowest hopcount

of 1. If the path passes through a single router, the hopcount increases to

2. Hopcount can increase to a maximum value of 16, which is RIP’s

“inﬁnity metric,” an indication that a network or node cannot be reached.

If gated encounters an unreachable node, it goes into “Holddown Mode.”

Holddown Mode stops a node from propagating routing information until

the other nodes it is communicating with stabilize their routing

information.

Hosts with only one LAN interface may use the RIP protocol with gated

to passively listen to routing information when there is more than one

router on the LAN. If there is only one router on the LAN (leaving only

one path off the local LAN), you may prefer to conﬁgure a static route to

that router in /etc/rc.config.d/net, or issue the route command

manually, instead of running gated.

In certain cases you may not want trafﬁc to take a certain path, because

it incurs an unacceptable cost or security risk. In these cases, gated

allows you to assign a metric to each interface. This allows you to select

or bypass a path, regardless of its length or speed.

Conﬁguration Options

The -e and -a options help increase the RIP convergent time on HP-UX.

These command options can be set in /etc/gated.conf ﬁle under the

RIP protocol statement.

The -e option refers to route_expiry_time (Reviewers, exactly what is

this? Please deﬁne this term.). It speciﬁes the expiration time RIP

protocol will use for route aging. The minimum value is 1 second and the

maximum value is 180 seconds. The default is 180 seconds.

Using the -a option, you can speciﬁy the route_update_time. This is

the number of seconds the RIP protocol will take to send RIP updates to

its neighbors (Who are its neighbors? Other systems on the network?).

The minimum value is 1 second and the maximum value is 30 seconds.

The default is 30 seconds.