1. CCE1030 Computer Networking
Lecture 20
Routing Information Protocol RIPv2
Usama Arusi
January 2019
CCE1030 Usama Arusi

2. Objectives limitations of RIPv1’s limitations.
Apply the basic Routing Information Protocol Version 2 (RIPv2) configuration commands and evaluate RIPv2 classless routing updates.
Analyze router output to see RIPv2 support for VLSM and CIDR
Identify RIPv2 verification commands and common RIPv2 issues
January 2019
CCE1030 Usama Arusi

3. Content RIPv1 vs RIPv2. RIPv1 Limitations. Configuring RIPv2.
RIPv2 & VLSM.
Verifying and Troubleshooting RIPv2.
January 2019
CCE1030 Usama Arusi

4. Difference between RIPv1 & RIPv2
A classful distance vector routing protocol
Does not support discontinuous subnets
Does not support VLSM
Does not send subnet mask in routing update
Routing updates are broadcast
RIPv2
A classless distance vector routing protocol that is an enhancement of RIPv1’s features
Next hop address is included in updates
Routing updates are multicast ( vs )
The use of authentication is an option
January 2019
CCE1030 Usama Arusi

5. Similarities between RIPv1 & RIPv2
Use of timers to prevent routing loops
Use of split horizon or split horizon with poison reverse
Use of triggered updates when there is a change in the topology for faster convergence.
Maximum hop count of 15 , with the hop count of 16 signifying an unreachable network.
January 2019
CCE1030 Usama Arusi

6. RIPv1 Limitations Lab Topology 3 router set up
Topology is discontiguous
There exists a static summary route
Static route information can be injected into routing table updates using redistribution.
Routers 1 & 3 contain VLSM networks
Remember that both the R1 and R3 routers have subnets that are part of the /16 major classful network (class B).
Also remember that R1 and R3 are connected to R2 using subnets of the /24 major classful network (class C).
This topology is discontiguous and will not converge because /16 is divided by the /24.
January 2019
CCE1030 Usama Arusi

7. RIPv1 Limitations Scenario Continued VLSM
-Recall this is sub netting the subnet
Private IP addresses are on LAN links
Public IP addresses are used on WAN links
Loopback interfaces
-These are virtual interfaces that can be pinged and added to routing table

8. RIPv1 Limitations Null Interfaces Static routes and null interfaces
This is a virtual interface that does not need to be created or configured
-Traffic sent to a null interface is discarded
-Null interfaces do not send or receive traffic
Static routes and null interfaces
null interfaces will serve as the exit interface for static route
-Example of configuring a static supernet route with a null interface
-R2(config)#ip route Null0

9. RIPv1 Limitations Route redistribution
- Redistribution involves taking the routes from one routing source and sending those routes to another routing source.
In our example topology, we want the RIP process on R2 to redistribute our static route ( /16) by importing the route into RIP and then sending it to R1 and R3 using the RIP process.
-Example : R2(config-router)#redistribute static

10. Verifying and Testing Connectivity
show ip interfaces brief
To test whether or not the topology has full connectivity, we first verify that both serial links on R2 are up using the show ip interface brief
Ping
Whenever R2 pings any of the subnets on R1 or R3, only about 50% of the ICMP are successful.
R1 is able to ping but is unsuccessful when attempting to ping the on R3
R3 is able to ping but is unsuccessful when attempting to ping the on R1.

11. RIPv1 Limitations RIPv1 – a classful routing protocol
Subnet mask are not sent in updates
Summarizes networks at major network boundaries
RIPv1 cannot support discontiguous networks, VLSM, or CIDR.
if network is discontiguous and RIPv1 configured convergence will not be reached
RIPv1 on both the R1 and R3 routers will summarize their subnets to the classful major network address of when sending routing updates to R2.
From the perspective of R2, both updates have an equal cost of 1 hop to reach network /16. As you will see, R2 installs both paths in the routing table.

12. RIPv1 Limitations Examining the routing tables
To examine the contents of routing updates use the debug ip rip command
R2 is receiving two equal cost routes with a metric of 1 hop. R2 is receiving one route on Serial 0/0/0 from R1 and the other route on Serial 0/0/1 from R3.
R2 has two equal cost routes to the /16 network.

13. RIPv1 Limitations R4 is added to the topology connected to R3
Because RIPv1 does not send the subnet mask in routing updates, it cannot support VLSM.
R3 router is configured with VLSM subnets, all of which are members of the class B network /16:
/24 (FastEthernet 0/0)
/24 (Loopback 0)
/28 (Loopback 1)
/28 (Loopback 2)
As we saw with the /16 updates to R2 by R3,
RIPv1 either summarizes the subnets to the classful boundary
or uses the subnet mask of the outgoing interface to determine which subnets to advertise.
R4 is added to the topology connected to R3

14. RIPv1 Limitations R4 is added to the topology connected to R3
Why is RIPv1 on R3 not including the other subnets, /28 and /28, in updates to R4?
Those subnets do not have the same subnet mask as FastEthernet 0/0.
R3 will only include those routes in its routing table with the same mask as the exit interface.
Since the interface is with a /24 mask, it will only include subnets with a /24 mask. The only one that meets this condition is
The other subnets, /28 and /28, are not included because the /28 masks do not match the /24 mask of the outgoing interface.
R4 is added to the topology connected to R3

15. RIPv1 Limitations No CIDR Support
R2(config)#ip route Null0
the static route is included in R2's routing table, but R2 will not include the static route in its update
R1 is not receiving this /16 route in its RIP updates from R2,
Reason: Classful routing protocols do not support CIDR routes that are summarized with a smaller mask than the classful subnet mask
If the static route were configured with a /24 mask or greater, this route would be included in the RIP updates.

16. Configuring RIPv2 Comparing RIPv1 & RIPv2 Message Formats
RIPv2 Message format is similar to RIPv1 but has 2 extensions
1st extension is the subnet mask field
allows a 32 bit mask to be included in the RIP route entry.
the receiving router no longer depends upon the subnet mask of the inbound interface or the classful mask when determining the subnet mask for a route
2nd extension is the addition of next hop address
The Next Hop address is used to identify a better next-hop address - if one exists - than the address of the sending router.
If the field is set to all zeros ( ), the address of the sending router is the best next-hop address.

17. Configuring RIPv2 RIPv1 RIPv2 Enabling and Verifying RIPv2
Configuring RIP on a Cisco router
By default it is running RIPv1
Even though the router only sends RIPv1 messages, it can interpret both RIPv1 and RIPv2 messages.
A RIPv1 router will just ignore the RIPv2 fields in the route entry.
RIPv1
RIPv2

18. Configuring RIPv2 Configuring RIPv2 on a Cisco router
-Requires using the version 2 command
-RIPv2 ignores RIPv1 updates
To verify RIPv2 is configured use the
show ip protocols command

19. Configuring RIPv2 Auto-Summary & RIPv2
RIPv2 will automatically summarize routes at major network boundaries and can also summarize routes with a subnet mask that is smaller than the classful subnet mask

20. Configuring RIPv2 Disabling Auto-Summary in RIPv2
To disable automatic summarization issue the no auto-summary command

21. Configuring RIPv2 Verifying RIPv2 Updates
When using RIPv2 with automatic summarization turned off
Each subnet and mask has its own specific entry, along with the exit interface and next-hop address to reach that subnet.
To verify information being sent by RIPv2 use the
debug ip rip command

22. VLSM & CIDR RIPv2 and VLSM Networks using a VLSM IP addressing scheme
Use classless routing protocols (i.e. RIPv2) to disseminate network addresses and their subnet masks

23. VLSM & CIDR CIDR uses Supernetting
Supernetting is a bunch of contiguous classful networks that is addressed as a single network.

24. VLSM & CIDR
To verify that supernets are being sent and received use the following commands
-Show ip route
-Debug ip rip

25. Verifying & Troubleshooting RIPv2
Basic Troubleshooting steps
-Check the status of all links
-Check cabling
-Check IP address & subnet mask configuration
-Remove any unneeded configuration commands
Commands used to verify proper operation of RIPv2
Show ip interfaces brief
Show ip protocols
Debug ip rip
Show ip route

26. Verifying & Troubleshooting RIPv2
Common RIPv2 Issues
When trouble shooting RIPv2 examine the following issues:
Version
Check to make sure you are using version 2
Network statements
Network statements may be incorrectly typed or missing
Automatic summarization
If summarized routes are not needed then disable automatic summarization

27. Summary RIPv1 Yes No RIPv2 Routing Protocol Distance Vector Classless
Uses
Hold-Down
Timers
Use of
Split Horizon or
Split Horizon w/
Poison Reverse
Max
Hop count
= 15
Auto
Summary
Support
CIDR
Supports
VLSM
Uses Authen-tication
RIPv1
Yes No
RIPv2