3Com SuperStack 4 Configuration Manual page 111

Before RIP completely deletes an unreachable route from the routing table, it
advertises the route by sending four update packets with a route metric of 16, to
let all the neighbors know 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 of that 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 117 Configuring Zero Field Check of the Interface Packets
Operation
Configure zero field check on the RIP-1 packet
Disable zero field check on the RIP-1 packet
Specifying the Operating State of the Interface
In the Interface View, you can specify whether RIP update packets are sent and
received on the interface. In addition, you can specify whether an interface sends
or receives RIP update packets.
Perform the following configuration in Interface View:
Table 118 Specifying the Operating State of the Interface
Operation
Enable the interface to run RIP
Disable the interface from running RIP
Enable the interface to receive RIP update packets
Disable the interface from receiving RIP update packets undo rip input
Enable the interface to send RIP update packets
Disable the interface from sending RIP update packets undo rip output
The command and the
undo rip work
not the same functions. The
forward the route of the interface applying this command. The
command prevents other interfaces from forwarding the route of the interface
applying this command, and it appears that this interface has been removed.
In addition, the
rip work
and
input rip output
By default, all interfaces except loopback interfaces both receive and transmit RIP
update packets.
undo network
command allows other interfaces to
undo rip work
command is functionally equivalent to both the
commands.
Command
checkzero
undo checkzero
Command
rip work
undo rip work
rip input
rip output
command have similar but
undo network
RIP 123
rip