Description

This article describes the issue of RIP packets being ignored by Junos, if they are not from UDP port 520.

Symptoms

Customers may claim that Juniper EX failed to establish RIP connections from the source UDP port, if it is not equal to 520; but Cisco runs normally to the same RIP traffic.

Solution


According to the RFC1058 Routing Information Protocol, it provides the following information in section 3.4.2:

3.4.2. Response
Because processing of a response may update the host's routing table, the response must be checked carefully for validity. The response
must be ignored if it is not from port 520.

Juniper complied with the RFC1058 strictly, if a Junos device received RIP packets with the source port other than 520, it will drop the packets and create a log similar to the following message in Syslog:


24 Mar 23 11:04:18.061468 Ignoring RIP packet with source port not 520, source port is 4369