When RIP is configured on a router, by default, the software receives RIP
Version 1 (RIP v1) and RIP Version 2 (RIP v2) packets, but sends only RIP v1
packets. To send and receive only RIP v1 packets, the router must be configured
with the command version 1 under router
rip. To send and receive only RIP v2 packets, the router must be
configured with the command version 2 under router
rip. When the version command is used, by
default, updates from other routers sending other than the specified version
are ignored.
This example shows two routers running RIP between each
other.
Debugs
and Verification Figure
shows
the configuration of router R2. In this configuration, RIP is configured to
send and receive only Version 1 packets. The default RIP configuration, without
the version 1 command, will allow the router to receive
both Version 1 and 2 packets.
Figure
shows the output
of the debug ip rip command. This command reveals that
router R2 is receiving a RIP packet from router R1, which is configured to send
Version 2 updates.
Figure
shows the output
of the show ip protocols command, which indicates that the
Ethernet 0 interface is sending and receiving RIP v1 packets. This means that
if a Version 2 packet is received on Ethernet 0 of R2, it will be ignored
because the interface can send and receive only Version 1 packets.
Figure
shows the
configuration of router R1. This shows that the sender R1 is configured to only
send and receive Version 2 packets.
Figure
shows the output
of the show ip protocols command, which shows that sender
R1 is sending and receiving only Version 2 packets. This is because of the
version 2 command that is configured under router RIP.
Solution A solution is to configure all routers to run RIP v2.
However, there may be times when this is not possible, and some routers can
only run RIP v1. Therefore, another solution is to configure the appropriate
interfaces to send and receive the appropriate RIP v1 or RIP v2 packets.
If the receiver, R2, is configured to receive only RIP v1 packets, it will
ignore the RIP v2 updates. Router R1 must be configured on the sender side so
that it will send both Version 1 and Version 2 packets. When R2 receives the
Version 1 packet, it will install the routes in the routing table. R2 will
ignore RIP v2 packets because it is configured for RIP v1.
Figure
shows the new
configuration for R1. In this configuration the sender, the R1 Ethernet 0
interface, is configured to send and receive both RIP v1 and RIP v2 packets.
Figure
shows the output
of show ip protocols, which indicates that the Ethernet 0
interface is sending and receiving Version 1 and Version 2 packets. The
advantage to sending both Version 1 and Version 2 updates is that, if any
devices on this Ethernet segment are running Version 1 only or Version 2 only,
those devices will be capable of communicating with router R1 on this Ethernet
segment.
Figure
shows router R2 routing table after the configuration change.
Lab
Exercise: Troubleshooting Problems at the Physical, Data Link, and Network
Layers III
After completing this lab, the student will be able to follow
a logical troubleshooting process to define, isolate, and correct problems
outlined in a trouble ticket.