Checking the validity of RIP Update packets improves network security. Validity check includes zero field check for RIP-1 packets and source address check for RIP Update packets.
Zero field check
In RIP-1 packets, the values of some fields must be zero. These fields are zero fields. After zero field check is enabled, a switch checks the zero fields in RIP-1 packets and discards the packets in which the zero field values are not 0.
Source address check
Source address check for RIP Update packets verifies the source IP address of received RIP Update packets. Specifically, a switch checks whether the IP address of the interface that sends the packet is in the same network segment as that of the interface that receives the packet. If the IP addresses are not in the same network segment, the switch will not process the RIP packet.