Specifying the Operating State of the Interface

RIP 93

In fact, you may find that the timeout time of garbage-collection timer is not fixed. If period update timer is set to 30 seconds, garbage-collection timer might range from 90 to 120 seconds.

Before RIP completely deletes an unreachable route from the routing table, it advertises the route by sending four update packets with route metric of 16, to let all the neighbors knows that the route is unreachable. Routes do not always become unreachable when a new period starts so the actual value of the garbage-collection timer is 3 to 4 times the value of the period update timer.

You must consider network performance when adjusting RIP timers, and configure all the routes that are running RIP, so as to avoid unnecessary traffic or network oscillation.

Configuring RIP-1 Zero Field Check of the Interface Packet

According to the RFC1058, some fields in the RIP-1 packet must be 0. When an interface version is set to RIP-1, the zero field check must be performed on the packet. If the value in the zero field is not zero, processing is refused. There are no zero fields in RIP-2 packets so configuring a zero field check is invalid for RIP-2.

Perform the following configurations in RIP view.

Table 88 Configuring Zero Field Check of the Interface Packet

Operation	Command

Configure zero field check on the RIP-1 packet	checkzero
Disable zero field check on the RIP-1 packet	undo checkzero

By default, RIP-1 performs zero field check on the packet.