1. Chapter 7 RIP version 2

2. RIPv1 Limitations RIPv1: Topology Limitations
RIPv1: Discontiguous Networks
RIPv1: No VLSM Support
RIPv1: No CIDR Support

3. RIPv1: Distance Vector, Classess Routing Protocol
RIP Version 2 (RIPv2) is defined in RFC 1723.
RIPv2 is the first classless routing protocol discussed in this book.
RIPv2 has lost popularity when compared to other routing protocols such as EIGRP, OSPF and IS-IS.
RIPv2, it is ideal for explaining the differences between a classful routing protocol (RIPv1) and a classless routing protocol (RIPv2).

4. RIPv1 and RIPv2
RIPv2 is actually an enhancement of RIPv1’s features and extensions rather than an entirely new protocol.
Next-hop addresses included in the routing updates
Use of multicast addresses in sending updates
Authentication option available
Both versions of RIP share the following features and limitations:
Use of hold-down and other timers to help prevent routing loops
Use of split horizon and split horizon with poison reverse to also help prevent routing loops
Use of triggered updates when there is a change in the topology for faster convergence
Maximum hop count of 15 hops, with the hop count of 16 signifying an unreachable network

5. RIPv1 Limitations
/16
/16
In a discontiguous network, a classful major network address, such as /16, is separated by one or more other major networks.
/16 is divided by the networks:
/30
/30
Classful routing protocols do not include enough routing information to route properly for discontiguous networks.

6. Summary Route
R2(config)# ip route null0
R2(config-router)#redistribute static
/16
/16
R2: static summary route to the /16 network.
Redistribution - Inject static route(s) into routing protocol updates.

7. VLSM 172.30.0.0/16 172.30.0.0/16 R1 and R3 contain VLSM networks.
Both R1 and R3 are configured with /24 subnets of the /16 network.
R3: /24 subnetted again, using the first 4 bits for subnets and the last 4 for hosts.
/28 and /28

8. VLSM
R3: /24 subnetted again, using the first 4 bits for subnets and the last 4 for hosts.
/28 and /28

9. Loopback Interfaces 172.30.0.0/16 172.30.0.0/16 Loopback interface
Software-only interface
Used to emulate an interface.
Can be assigned an IP address.
Specific purposes with some routing protocols such as OSPF (later)
A loopback interface can be:
pinged
subnet advertised in routing updates.
Ideal for simulating multiple networks attached to the same router.

10. RIPv1 Topology Limitations
R1(config)# router rip
R1(config-router)# network
R1(config-router)# network
R2(config)# ip route null0
R2(config)# router rip
R2(config-router)# redistribute static
R2(config-router)# network
R2(config-router)# network
R3(config)# router rip
R3(config-router)# network
R3(config-router)# network
RIPv1 configuration for all three routers

11. Static Routes and Null Interfaces
R2(config)# ip route Null0
CIDR allows route aggregation.
A single high-level route entry with a subnet mask less than the classful mask can be used to represent many lowerlevel routes.
This results in fewer entries in the routing table.
The static route on R2 is using a /16 mask to summarize all 256 networks ranging from /24 to /24.
For Lab purposes:
The static summary route /16 does not actually exist.
To simulate this static route, we will use a null interface as the exit interface.
You do not need to enter commands to create or configure the null interface.
It is always up but does not forward or receive traffic.
Traffic sent to the null interface is discarded.

12. Route Redistribution
R2(config)# ip route null0
R2(config)# router rip
R2(config-router)# redistribute static
Is static route being sent via RIPv1 with other RIPv1 routes?
Redistribution involves taking the routes from one routing source and sending those routes to another routing source.
Routes can only be redistributed into a dynamic routing protocol.
Dynamic routing protocol to a different dynamic routing protocol.
Static routes to a dynamic routing protocol.
Directly connected networks to a dynamic routing protocol.
Want R2 to redistribute our static route ( /16) by importing the route into RIPv1 and then sending it to R1 and R3 using the RIPv1 process.

13. Verifying and Testing Connectivity
R2# ping
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
!U!.!
Success rate is 60 percent (3/5), round-trip min/avg/max = 28/29/32 ms
R2# ping
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
Success rate is 60 percent (3/5), round-trip min/avg/max = 28/28/28 ms
R2#
Whenever R2 pings any of the subnets on R1 or R3, only about 50 percent of the pings are successful.

14. Verifying and Testing ConnectivityX
R1# ping
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5),round-trip min/avg/max = 28/28/28 ms
R1# ping
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R1#
R1 is able to ping but is unsuccessful when attempting to ping the interface on R3.

15. Verifying and Testing ConnectivityX
R3# ping
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5),round-trip min/avg/max = 28/28/28 ms
R3# ping
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
R3#
R3 is able to ping but is unsuccessful when attempting to ping the interface on R1.
As you can see, there is an obvious problem when trying to communicate with the discontiguous subnets.

16. RIPv1: Discontiguous Networks
RIPv1 on both Routers R1 and R3 will summarize their subnets to the classful major network address of when sending routing updates to R2.

17. Examining the Routing Tables
R2# show ip route
R /16 [120/1] via , 00:00:09, Serial0/0/0
[120/1] via , 00:00:11, Serial0/0/1
/30 is subnetted, 2 subnets
C is directly connected, Serial0/0/1
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
C is directly connected, FastEthernet0/0
S /16 is directly connected, Null0
R2 has two equal-cost routes to the /16 network.
R1 and R3 are sending R2 a RIPv1 update for the network with a metric of 1 hop.
R2’s routing table only contains the major classful network address of and adds the Class B subnet mask of /16.

18. debug ip rip
R2# debug ip rip
RIP: received v1 update from on Serial0/0/0
in 1 hops
RIP: received v1 update from on Serial0/0/1
RIP: sending v1 update to via Serial0/0/0 ( )
RIP: build update entries
network metric 1
subnet metric 1
RIP: sending v1 update to via Serial0/0/1 ( )
subnet metric 1
R2 is receiving two equal-cost routes with a metric of 1 hop:
one route on Serial 0/0/0 from R1 and
the other route on Serial 0/0/1 from R3.
Also notice that the subnet mask is not included with the network address in the update.

19. show ip route R1 has its own 172.30.0.0 routes: 172.30.2.0/24
R1# show ip route
/24 is subnetted, 2 subnets
C is directly connected, Loopback0
C is directly connected, FastEthernet0/0
/30 is subnetted, 2 subnets
R [120/1] via , 00:00:16,Serial0/0/0
C is directly connected, Serial0/0/0
R /8 [120/1] via , 00:00:16, Serial0/0/0
R1#
R1 has its own routes:
/24
/24.
R1 does not send R2 those subnets.
R1 and R3 are boundary routers only sending the summarized
Result, R2 only knows about the /16 classful network and is unaware of any subnets.

20. How Classful Routing Protocols Determine Subnet Masks
Apply classful default mask of /16
Apply classful default mask of /16

21. How Classful Routing Protocols Determine Subnet Masks
Apply classful default mask of /8
Apply classful default mask of /8

22. How Classful Routing Protocols Determine Subnet Masks
VLSM issues: will discuss next

23. RIPv1: No VLSM Support
Because RIPv1 does not send the subnet mask in routing updates, it cannot support VLSM.
The R3 router is configured with the following 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)

24. RIPv1: No CIDR Support
R2(config)# ip route null0
R2(config)# router rip
R2(config-router)# redistribute static
R2(config-router)# network
R2(config-router)# network
R2(config-router)# end
R2# show ip route
R /16 [120/1] via , 00:00:09, Serial0/0/0
[120/1] via , 00:00:11, Serial0/0/1
/30 is subnetted, 2 subnets
C is directly connected, Serial0/0/1
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
C is directly connected, FastEthernet0/0
S /16 is directly connected, Null0
We see the static route, let’s see if it is be sent in RIPv1 updates with the other RIPv1 routes…

25. R1 Routing Table
R1# show ip route
/24 is subnetted, 2 subnets
C is directly connected, FastEthernet0/1
C is directly connected, FastEthernet0/0
/30 is subnetted, 2 subnets
R [120/1] via , 00:00:16,Serial0/0/0
C is directly connected, Serial0/0/0
R /8 [120/1] via , 00:00:16, Serial0/0/0
Notice that R1 is not receiving this /16 route in its RIP updates from R2

26. debug ip rip
R2# debug ip rip
RIP: received v1 update from on Serial0/0/0
in 1 hops
RIP: received v1 update from on Serial0/0/1
RIP: sending v1 update to via Serial0/0/0 ( )
RIP: build update entries
network metric 1
subnet metric 1
RIP: sending v1 update to via Serial0/0/1 ( )
subnet metric 1
R2 is not including the /16 route in its RIPv1 updates to either R1 or R3.

27. RIPv1: No CIDR Support The static route 192.168.0.0 has a /16 mask.
R2(config)# ip route null0
R2(config)# router rip
R2(config-router)# redistribute static
The static route has a /16 mask.
This is fewer bits than the classful Class C mask of /24.
RIPv1 and other classful routing protocols cannot support CIDR routes that are summarized routes with a smaller subnet mask than the classful mask of the route.
RIPv1 ignores these supernets in the routing table and does not include them in updates to other routers.
This is because the receiving router would only be able to apply the larger /24 classful mask to the update and not the shorter /16 mask.
Note:
If the static route were configured with a /24 mask or greater, this route would be included in the RIP updates.
The receiving routers would apply the classful /24 mask to this update.

28. Configuring RIPv2 Enabling and Verifying RIPv2 Auto-Summary and RIPv2
Disabling Auto-Summary in RIPv2
Verifying RIPv2 Updates

29. Configuring RIPv2
Configuring RIPv2 is similar to configuring RIPv1, with the addition of a single RIP command, version 2.
Although RIPv2 uses the same basic configuration commands as RIPv1, the results of using RIPv2 are different, allowing both CIDR and VLSM to be used in the network.

30. Enabling and Verifying RIPv2
R2# show ip protocols
<output omitted>
Default version control: send version 1, receive any version
Interface Send Recv Triggered RIP Key-chain
Serial0/0/
Serial0/0/
Automatic network summarization is in effect
<output omitted >
Default RIPv1: When configuring RIP
Router only sends RIPv1 messages, it can process both RIPv1 and RIPv2 messages.
Ignore the RIPv2 fields in the route entry.
RIPv2 will ignore RIPv1 updates.

31. Enabling and Verifying RIPv2
R1(config)# router rip
R1(config-router)# version 2
R2(config)# router rip
R2(config-router)# version 2
R3(config)# router rip
R3(config-router)# version 2
version 2 command is used to modify RIP to use Version 2.
This command should be configured on all routers in the routing domain.

32. Enabling and Verifying RIPv2
R2# show ip protocols
Routing Protocol is “rip”
Sending updates every 30 seconds, next due in 1 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is
Incoming update filter list for all interfaces is
Redistributing: static, rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
Serial0/0/
Serial0/0/
Automatic network summarization is in effect
<output omitted for brevity>

33. Restoring RIP to Version 1
R1(config)# router rip
R1(config-router)# version 1
!or
R1(config-router)# no version
Default behavior of RIPv1 can be restored by using either the (slightly different behaviors in sending and receiving):
version 1 command
no version command
If done, should be configured on all routers.

34. Auto-Summary and RIPv2
R2# show ip route
R /16 [120/1] via , 00:00:28, Serial0/0/0
[120/1] via , 00:00:18, Serial0/0/1
/30 is subnetted, 2 subnets
C is directly connected, Serial0/0/1
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
C is directly connected, FastEthernet0/0
S /16 is directly connected, Null0
You still see the summarized /16 route with the same two equal-cost paths.

35. Auto-Summary and RIPv2
R1# show ip route
/24 is subnetted, 2 subnets
C is directly connected, Loopback0
C is directly connected, FastEthernet0/0
/30 is subnetted, 2 subnets
R [120/1] via , 00:00:04,Serial0/0/0
C is directly connected, Serial0/0/0
R /8 [120/1] via , 00:00:04, Serial0/0/0
R /16 [120/1] via , 00:00:04, Serial0/0/0
Routers R1 and R3 still do not include the subnets of the other router.
The only difference so far between RIPv1 and RIPV2 is that R1 and R3 each have a route to /16.
This route was the (CIDR) static route configured on R2 and redistributed by RIP.
What’s happening?

36. Auto-Summary and RIPv2
R1# debug ip rip
RIP: sending v2 update to via Serial0/0/0 ( )
RIP: build update entries
/16 via , metric 1, tag 0
<output omitted for brevity>
RIP: received v2 update from on Serial0/0/0
/8 via in 1 hops
/16 via in 1 hops
/30 via in 1 hops
Notice that RIPv2 is sending both the network address and subnet mask.
Notice that the route sent is the summarized classful network address, /16
not the individual /24 and /24 subnets.

37. Auto-Summary and RIPv2
R1# show ip protocols
Routing Protocol is “rip”
<output omitted>
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
FastEthernet0/
FastEthernet0/
Serial0/1/
Automatic network summarization is in effect
By default, RIPv2 automatically summarizes networks at major network boundaries, just like RIPv1.
Both R1 and R3 routers are still summarizing their subnets to the Class B address of when sending updates out their interfaces on the and networks, respectively.

38. Disabling Auto-summary in RIPv2
R2(config)# router rip
R2(config-router)# no auto-summary
R3(config)# router rip
R3(config-router)# no auto-summary
R1(config)# router rip
R1(config-router)# no auto-summary
R1# show ip protocols
<output omitted>
Automatic network summarization is not in effect
To modify the default RIPv2 behavior of automatic summarization, use the no auto-summary command

39. Verifying RIPv2 Updates
R2# show ip route
/16 is variably subnetted, 6 subnets, 2 masks
R /28 [120/1] via , 00:00:09, Serial0/0/1
R /28 [120/1] via , 00:00:09, Serial0/0/1
R /24 [120/1] via , 00:00:03, Serial0/0/0
R /24 [120/1] via , 00:00:03, Serial0/0/0
R /24 [120/1] via , 00:00:09, Serial0/0/1
R /24 [120/1] via , 00:00:09, Serial0/0/1
/30 is subnetted, 2 subnets
C is directly connected, Serial0/0/1
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
C is directly connected, FastEthernet0/0
S /16 is directly connected, Null0
The routing table for R2 now contains the individual subnets for /16.
Notice that a single summary route with two equal-cost paths no longer exists.
Each subnet and mask has its own specific entry, along with the exit interface and next-hop address to reach that subnet.

40. Verifying RIPv2 Updates
R1# show ip route
/16 is variably subnetted, 6 subnets, 2 masks
R /28 [120/2] via , 00:00:01, Serial0/0/0
R /28 [120/2] via , 00:00:01, Serial0/0/0
C /24 is directly connected, Loopback0
C /24 is directly connected, FastEthernet0/0
R /24 [120/2] via , 00:00:01, Serial0/0/0
R /24 [120/2] via , 00:00:01, Serial0/0/0
/30 is subnetted, 2 subnets
R [120/1] via , 00:00:02, Serial0/0/0
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
R [120/1] via , 00:00:02, Serial0/0/0
R /16 [120/1] via , 00:00:02, Serial0/0/0
Fully converged routing tables.

41. Verifying RIPv2 Updates
R3# show ip route
/16 is variably subnetted, 6 subnets, 2 masks
C /28 is directly connected, Loopback2
C /28 is directly connected, Loopback1
R /24 [120/2] via , 00:00:01, Serial0/0/1
R /24 [120/2] via , 00:00:01, Serial0/0/1
C /24 is directly connected, FastEthernet0/0
C /24 is directly connected, Loopback0
/30 is subnetted, 2 subnets
C is directly connected, Serial0/0/1
R [120/1] via , 00:00:02, Serial0/0/1
/16 is subnetted, 1 subnets
R [120/1] via , 00:00:02, Serial0/0/1
R /16 [120/1] via , 00:00:02, Serial0/0/1
Fully converged routing tables.

42. Verifying RIPv2 Updates
R2# debug ip rip
RIP: received v2 update from on Serial0/0/1
/24 via in 1 hops
/24 via in 1 hops
/28 via in 1 hops
/28 via in 1 hops
RIP: sending v2 update to via Serial0/0/0 ( )
RIP: build update entries
/16 via , metric 1, tag 0
/24 via , metric 2, tag 0
/24 via , metric 2, tag 0
/28 via , metric 2, tag 0
/28 via , metric 2, tag 0
/16 via , metric 1, tag 0
/30 via , metric 1, tag 0
Sending and receiving routing updates, which are individual routes with their subnet mask instead of a single summary route with the classful mask.

43. Verifying RIPv2 Updates
R2# debug ip rip
RIP: sending v2 update to via Serial0/0/0 ( )
Notice also that the updates are sent using the multicast address
RIPv1 sends updates as a broadcast
In general multicast updates:
Take up less bandwidth on the network.
Require less processing by devices that are not RIP enabled.

44. RIPv2 and VLSM RIPv2 and CIDR
VLSM and CIDR
RIPv2 and VLSM
RIPv2 and CIDR

45. RIPv2 and VLSM
Added R4 for purposes of this discussion
With RIPv2, R3 can now include all the subnets in its routing updates to R4
This is because RIPv2 can include the proper subnet mask with the network address in the update.

46. RIPv2 and VLSM R3# debug ip rip
RIP: sending v2 update to via FastEthernet0/0 ( )
RIP: build update entries
/16 via , metric 2, tag 0
/24 via , metric 3, tag 0
/24 via , metric 3, tag 0
/24 via , metric 1, tag 0
/28 via , metric 1, tag 0
/28 via , metric 1, tag 0
/16 via , metric 2, tag 0
/30 via , metric 2, tag 0
/30 via , metric 1, tag 0

47. Verifying and Troubleshooting RIPv2
Verification and Troubleshooting Commands
Common RIPv2 Issues
Authentication

48. show ip route Command
R1# show ip route
/16 is variably subnetted, 6 subnets, 2 masks
R /28 [120/2] via , 00:00:01, Serial0/0/0
R /28 [120/2] via , 00:00:01, Serial0/0/0
C /24 is directly connected, Loopback0
C /24 is directly connected, FastEthernet0/0
R /24 [120/2] via , 00:00:01, Serial0/0/0
R /24 [120/2] via , 00:00:01, Serial0/0/0
/30 is subnetted, 2 subnets
R [120/1] via , 00:00:02, Serial0/0/0
C is directly connected, Serial0/0/0
/16 is subnetted, 1 subnets
R [120/1] via , 00:00:02, Serial0/0/0
R /16 [120/1] via , 00:00:02, Serial0/0/0
First command to use to check for network convergence.
Important to look for the routes that you expect to be in the routing table as well as for those that should not be in the routing table.

49. show ip interface brief Command
R1# show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/ YES NVRAM up up
FastEthernet0/ YES NVRAM up up
Serial0/0/ YES NVRAM up up
Serial0/0/ unassigned YES NVRAM down down
If a network is missing from the routing table, it is often because an interface is down or incorrectly configured.
The show ip interface brief command quickly verifies the status of all interfaces.

50. show ip protocols Command
R1# show ip protocols
Routing Protocol is “rip”
Sending updates every 30 seconds, next due in 29 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
FastEthernet0/
FastEthernet0/
Serial0/0/
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update
:00:18
Distance: (default is 120)
The show ip protocols command verifies several critical items, including whether RIP is enabled, the version of RIP, the status of automatic summarization, and the networks that were included in the network statements.

51. debug ip rip Command R2# debug ip rip
RIP: received v2 update from on Serial0/0/1
/24 via in 1 hops
/24 via in 1 hops
/28 via in 1 hops
/28 via in 1 hops
RIP: sending v2 update to via Serial0/0/0 ( )
RIP: build update entries
/16 via , metric 1, tag 0
/24 via , metric 2, tag 0
/24 via , metric 2, tag 0
/28 via , metric 2, tag 0
/28 via , metric 2, tag 0
/16 via , metric 1, tag 0
/30 via , metric 1, tag 0
debug ip rip is an excellent command to use to examine the contents of the routing updates that are sent and received by a router.
There can be times when a route is received by a router but is not added to the routing table.
One reason for this could be that a static route is also configured for the same advertised network.

52. ping Command
R2# ping
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 28/28/28 ms
R2# ping
Sending 5, 100-byte ICMP Echos to , timeout is 2 seconds:
An easy way to verify round-trip connectivity is with the ping command

53. show running-config Command
R1# show running-config !
hostname R1
interface FastEthernet0/0
ip address
interface FastEthernet0/1
ip address
interface Serial0/0/0
ip address
clock rate 64000
router rip
version 2
network
network
no auto-summary
<some output omitted for brevity>

54. Common RIPv2 Issues Version:
Although RIPv1 and RIPv2 can be made compatible with additional commands beyond the scope of this course, RIPv1 does not support discontiguous subnets, VLSM, or CIDR supernet routes.
network statements:
Another source of problems might be incorrectly configured or missing network statements configured with the network command.
Remember, the network command does two things:
It enables the routing protocol to send and receive updates on any local interfaces that belong to that network.
It includes the configured network in its routing updates to its neighboring routers.
A missing or incorrect network statement will result in missed routing updates and routing updates not being sent or received on an interface.
Automatic summarization:
If there is a need or expectation for sending specific subnets and not just summarized routes, make sure that automatic summarization has been disabled with the no auto-summary command.

55. Authentication
It is good practice to authenticate routing information.
RIPv2, EIGRP, OSPF, IS-IS, and Border Gateway Protocol (BGP) can be configured to encrypt and authenticate routing information.
Hides the content of the routing information
Routers will only accept routing information from other routers that have been configured with the same password or authentication information.
Covered in CIS 83.