ca ex s2 m07 ripv2

CCNA – Semester 2

Chapter 7: RIPv2

CCNA Exploration version 4.0

2

Overview

3

RIPv1 Limitations

4

Lab Topology

• This topology is discontiguous and will not converge because 172.30.0.0/16 is divided by the 209.165.200.0/24.

• R2 router has a static summary route to the 192.168.0.0/16 network. For now, understand that this summary route will cause problems with RIPv1 because 192.168.0.0/16 is not a major classful address and includes all of the /24 versions of 192.168.0.0/16

5

VLSM

• Notice that the R1 and R3 routers contain VLSM networks and

are sharing address space from the 172.30.0.0/16 major classful

network.

6

Lab Topology: Private Address

7

Lab Topology: Loopback interface

• A loopback interface is a software-only interface that is used

to emulate a physical interface.

• Like other interfaces, it can be assigned an IP address.

• Loopback interfaces are also used by other routing protocols,

such as OSPF, for different purposes.

8

RIPv1 Topology Limitations

9


• Static Routes and Null Interfaces

10


• Verifying and Testing Connectivity

11


• Verifying and Testing Connectivity

12


• Use the Packet Tracer Activity to practice your router configuration skills,

including RIPv1 configurations. 7.1.2.3

13

RIPv1: Discontiguous Networks

• RIPv1 is a classful routing protocol.

• It does not include the subnet masks in its routing updates.

• Therefore, RIPv1 cannot support discontiguous networks, VLSM, or Classless Inter-Domain Routing (CIDR) supernets.

14


• Because the subnet mask is not included in the update, RIPv1 and other classful routing protocols must summarize networks at major network boundaries.

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18

RIPv1: No VLSM Support

• Because RIPv1 does not send the subnet mask in routing updates, it cannot support VLSM.

• RIPv1 either summarizes the subnets to the classful boundary or uses the subnet mask of the outgoing interface to determine which subnets to advertise.

19

RIPv1: No CIDR support

• 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.

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21


• Use the Packet Tracer Activity in Simulation mode to see that updates are not sent across classful network boundaries with RIPv1. In RealTime mode, verify non-convergence with the show ip route, ping, and debug ip rip. 7.1.5.2

22

Configuring RIPv2

23

Enabling and Verifying RIPv2

• 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 (0.0.0.0), the address of the sending router

is the best next-hop address.

24

Enabling and Verifying RIPv2

25

Auto-summary and RIPv2

• By default, RIPv2 automatically summarizes networks at major

network boundaries, just like RIPv1.

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• Remember, the 192.168.0.0/16 route could not be distributed with

RIPv1 because the subnet mask was less than the classful mask.

• Because the mask is not included in RIPv1 updates, there was no way

for the RIPv1 router to determine what that mask should be. Therefore,

the update was never sent.

29

Disabling Auto-summay in RIPv2

30

Verifying RIPv2 Updates

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32


• Use the Packet Tracer Activity to configure RIPv2, disable

automatic summarization, and verify your configurations. 7.2.4.2

33

Compatibility with RIP v1

NewYork

interface fastethernet0/0

ip address 192.168.50.129 255.255.255.192

ip rip send version 1

ip rip receive version 1


ip address 172.25.150.193 255.255.255.240

ip rip send version 1 2


ip address 172.25.150.225 225.255.255.240

router rip

version 2

network 172.25.0.0

network 192.168.50.0

• Interface FastEthernet0/0 is configured to send and receive RIP v1 updates.

• FastEthernet0/1 is configured to send both version 1 and 2 updates.

• FastEthernet0/2 has no special configuration and therefore sends and receives version 2 by default.

RIPv2

34

Adding a default Routes to RIPv2

e0

ISP

SantaCruz2SantaCruz1

192.168.4.20/30

172.30.1.0/24

Internet

s0

s0 s0

s1

172.30.100.0/24

e0

192.168.4.24/30

.21

.22

.25

.26

10.0.0.0/8

e0.1

.1.1

Lo0Lo0

172.30.110.0/24172.30.2.0/24

.1.1

.1

static route to

207.0.0.0/8

207.0.0.0/16

207.1.0.0/16

207.2.0.0/16

207.3.0.0/16

etc.

`172.30.200.16/28

172.30.200.32/28

Lo1

Lo2

ISP

router rip

redistribute static

network 10.0.0.0

network 192.168.4.0

version 2

no auto-summary

default-information originate

ip route 207.0.0.0 255.0.0.0 null0

ip route 0.0.0.0 0.0.0.0 10.0.0.2

etherenet0

35

VLSM and CIDR

36

RIPv2 and VLSM

37

RIPv2 and CIDR

• One of the goals of Classless Inter-Domain Routing (CIDR) as

stated by RFC 1519 is "to provide a mechanism for the

aggregation of routing information." This goal includes the

concept of supernetting.

• A supernet is a block of contiguous classful networks that is

addressed as a single network.

38

RIPv2 and CIDR

39

Verifying and Troubleshooting RIPv2

40

Verification and Troubleshooting Commands

• There are several ways to verify and troubleshoot RIPv2. Many of the same commands used for RIPv2 can be used to verify and troubleshoot other routing protocols.

• It is always best to begin with the basics:

1. Make sure all of the links (interfaces) are up and operational.

2. Check the cabling.

3. Check to make sure you have the correct IP address and subnet mask on each interface.

4. Remove any unnecessary configuration commands that are no longer necessary or have been replaced by other commands.

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Router#show ip route

172.30.0.0/16 is variably subnetted, 6 subnets, 2 masks

C 172.30.200.32/28 is directly connected, Loopback2


R 172.30.2.0/24 [120/2] via 192.168.4.21, 00:00:21, Serial0

R 172.30.1.0/24 [120/2] via 192.168.4.21, 00:00:21, Serial0

C 172.30.100.0/24 is directly connected, Ethernet0


192.168.4.0/30 is subnetted, 2 subnets

R 192.168.4.24 [120/1] via 192.168.4.21, 00:00:21, Serial0

C 192.168.4.20 is directly connected, Serial0

R 10.0.0.0/8 [120/1] via 192.168.4.21, 00:00:21, Serial0

R 207.0.0.0/8 [120/1] via 192.168.4.21, 00:00:21, Serial0

Supernet, classless routing protcols

will route supernets (CIDR)

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Router#debug ip rip

RIP protocol debugging is on

Router#01:23:34: RIP: received v2 update from 192.168.4.22 on Serial1

01:23:34: 172.30.100.0/24 -> 0.0.0.0 in 1 hops

01:23:34: 172.30.110.0/24 -> 0.0.0.0 in 1 hops

Router#

01:23:38: RIP: received v2 update from 192.168.4.26 on Serial0

01:23:38: 172.30.2.0/24 -> 0.0.0.0 in 1 hops

01:23:38: 172.30.1.0/24 -> 0.0.0.0 in 1 hops

Router#

01:24:31: RIP: sending v2 update to 224.0.0.9 via Ethernet0 (10.0.0.1)

01:24:31: 172.30.2.0/24 -> 0.0.0.0, metric 2, tag 0

01:24:31: 172.30.1.0/24 -> 0.0.0.0, metric 2, tag 0

01:24:31: 172.30.100.0/24 -> 0.0.0.0, metric 2, tag 0

01:24:31: 172.30.110.0/24 -> 0.0.0.0, metric 2, tag 0

01:24:31: 192.168.4.24/30 -> 0.0.0.0, metric 1, tag 0

01:24:31: 192.168.4.20/30 -> 0.0.0.0, metric 1, tag 0

<text omitted>

Router(config)# line console 0

Router(config-line)# logging synchronous

multicast

Includes mask

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Router# show ip rip database

172.19.0.0/16 auto-summary

172.19.64.0/24 directly connected, Ethernet0

172.19.65.0/24

[1] via 172.19.70.36, 00:00:17, Serial1

[2] via 172.19.67.38, 00:00:25, Serial0

172.19.67.0/24 directly connected, Serial0



172.19.86.0/24[1] via 172.19.67.38, 00:00:25, Serial0

[1] via 172.19.70.36, 00:00:17, Serial1

• The show ip rip database command to check summary address entries

in the RIP database.

• These entries will appear in the database if there are only relevant child or

specific routes being summarized.

• When the last child route for a summary address becomes invalid, the

summary address is also removed from the routing table.

Router#show ip rip database

48

Common RIPv2 issues

• The network statement does two things:

– It enables the routing protocol to send and receive updates

on any local interfaces that belong to that network.

– It includes that network in its routing updates to its

neighboring routers.

49

Authentication

• Whatever the reason, it is good practice to authenticate routing information transmitted between routers.

• RIPv2, EIGRP, OSPF, IS-IS, and BGP can be configured to authenticate routing information.

• This practice ensures routers will only accept routing information from other routers that have been configured with the same password or authentication information.

• Note: Authentication does not encrypt the routing table.

50

Configuring authentication

Router(config)#key chain Romeo

Router(config-keychain)#key 1

Router(config-keychain-key)#key-string Juliet

• The password must be the same on both routers (Juliet), but the name of

the key (Romeo) can be different.

Router(config)#interface fastethernet 0/0

Router(config-if)#ip rip authentication key-chain Romeo

Router(config-if)#ip rip authentication mode md5

• If the command ip rip authentication mode md5 is not added, the interface

will use the default clear text authentication. Although clear text authentication

may be necessary to communicate with some RIP v2 implementations, for

security concerns use the more secure MD5 authentication whenever possible.

51

RIPv2 Configuration Labs

52

Summary

ca ex s2 m07 ripv2

Technology

ripv1 updates

ripv1 router

ripv1 limitations

ripv1 configurations

discontiguous networks

cidr support ripv1

ripv1 topology limitations8

ripv2 updates