Section 19: RIP – The Routing Information Protocol

  ICND1 CCENT

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59% Complete

RIP Commands Review

Initial Configuration

  • Enable RIP
(config)# router rip
  • Set RIP Version
(config-router)# version 2
  • Disable auto-summary mask (automatically sets the classful subnet mask)
(config-router)# no auto-summary
    • Instead, it is best to manually summerise
      • This is set on the interface that advertises the network, NOT the interface connected to the network!
r02(config)#int f0/0
(config-if)#ip summary-address rip 10.1.0.0 255.255.0.0
  • Set the advertised classful network
    • (config-router)# network <IP.ADD.RE.SS>
      • network 10.0.0.0
      • network 172.16.0.0
      • network 192.168.1.0
  • Set a passive interface (Read, but do not send routing information)
    • (config-router)# passive-interface <interface_id>
      • passive-interface loopback 0
      • passive-interface fastethernet 1/0
      • passive-interface f0/2
  • Set all interfaces as passive by default
    • (config-router)# passive-interfaces default
  • Over-ride default passive-interfaces
    • (config-router)# no passive-interface <interface_id>
  • Over-ride default timers
    • (config-router)#timers basic <Update> <Invalid> <Hold Down> <Flush>
      • timers basic 30 180 180 240
  • Advertise the default route
    • (config-router)# default-information originate
  • Setting a summary-route – This must be set for the interface that advertises the route and not on the interface that connects to that route!
    • (config-if)# ip summary-address <IP.ADD.RE.SS> <NET.WORK.MA.SK>

Debug Commands

  • Watch RIP in real time
    • debug ip rip
  • Show RIP database
    • # show ip rip database
  • Show all RIP settings
    • # show ip protocols
  • Show all enabled routing protocols
    • # show ip protocols
  • Show RIP timers
    • # show ip protocols | include seconds
  • Show learned routes
    • # show ip route

 

119. RIP Introduction

https://www.udemy.com/cisco-icnd1/learn/lecture/8631702#content

 

120. RIP – The Routing Information Protocol

https://www.udemy.com/cisco-icnd1/learn/lecture/8631706#content

RIP Characteristics

  • RIP is a Distance Vector Protocol
  • It uses hop count as its metric
  • The maximum hop count is 15
  • It will perform Equal Cost Multi Path, for up to 4 paths by default

RIPv1 vs v2 vs ng (Next Generation)

  • RIPv1 is legacy and is typically not used at all anymore, although it is still supported.
  • RIPv1 does not send subnet mask information with routing updates, so Variable Length Subnet Masking (VLSM) is not supported.  RIPv2 does support VLSM.
  • RIPv1 updates are sent every 30 seconds as Broadcast traffic.  RIPv2 uses Multicast address 224.0.0.9
  • RIPng (Next Generation) supports IPv6
    • RIPng and RIPv1 are NOT covered on the CCNA exam.

RIPv2 Configuration

configure terminal
router rip
version 2
network 10.0.0.0
  • The ‘network’ command should be a classful network.  No subnet mask is specified.

Auto-Summary

  • RIP will automatically summarize routes to the classful boundary by default.
  • For example:
    • 192.168.10.1/30 will be advertised as 192.168.10.0/24
    • 172.16.10.1/30 will be advertised as 172.16.0.0/16
  • This is almost never desirable.
  • To disable auto-summary use ‘no auto-summary’
router rip
no auto-summary

Manual Summerization

  • Manual summerization gives you control of exactly ho you summarize.
  • The individual summarized routes are not advertised – only their summary route
  • Notice the summary address is advertised on the interface that the route is sent OUT of.. not the interface connected to that route!
      • This suggests that if you have multiple interfaces, each interface NOT connected to the summary route will need to have this configured?
      • Since RIP is generally only used on very small networks, this is probably not much of an issue.

R2(config)#interface f1/0
R2(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0

How to identify if RIP is enabled

Show IP Protocols

show ip protocols

Check running-config

show run | section rip

Check the routing table

show ip route

Check the RIP database

  • This is useful to see if RIP routes were ever learned, even if they are not used in the routing table.
show ip rip database

60% Complete!

121. RIP Advanced Topics

https://www.udemy.com/cisco-icnd1/learn/lecture/8631708#content

Passive Interfaces

  • Passive Interfaces work differently in RIP than other protocols.
  • With other routing protocols, a passive interface will not send out or listen for routing updates
    • The network configured on the interface will be advertised to other peer routers running the routing protocol.
  • In RIP, a passive interface does not send out updates, but it does listen to incoming updates from other RIP speaking neighbors.
  • The router can receive updates on the passive interface and use them in the routing table.

Passive Interface Configuration

R1(config)#router rip
R1(config-router)#passive-interface loopback 0
R1(config-router)#passive-interface f2/0
  • This will receive information on both Loopback 0 and f2/0
  • It will not send any information out either of these interfaces.

Setting Passive Interfaces as default

  • If most routes are passive (you don’t want to send out routing information as a rule of thumb), you can set the default to be passive and manually configure the interfaces you do want to send out on.
R1(config)#router rip
R1(config-router)#passive-interface default
R1(config-router)#no passive-interface f0/0
R1(config-router)#no passive-interface f1/0
R1(config-router)#no passive-interface f3/0

Default Route Injection

  • Used to configure a default static route going out to the Internet.
  • It would be time consuming and hard to manage manually if a change was made.
  • Configure it on the outbound router, then inject it into RIP to share with the other routers.
  • The other routers will then share that route with each other automatically (no extra configuration necessary.)
R4(config)#ip route 0.0.0.0 0.0.0.0 203.0.113.2
R4(config)#router rip
R4(config-router)#default-information originate
R1#show ip route
...
R     0.0.0.0./0 [120/2] via 10.0.3.2, 00:00:21, FastEthernet3/0
...

RIP Default Timers

  • Update: The router sends updates every 30 seconds
  • Invalid: After no updates for 180 seconds, the route becomes invalid.
    • You would have lost 6 updates (by default) before marking a route as invalid.
  • Hold Down: The hold down timer is used to stabilize the network.
    • It starts when the invalid timer expires.
    • When a route enters hold down, it can’t be installed even if there is a new router with a better metric.
      • In case you have a network connection that is going up and down.
    • 180 seconds by default.
  • Flush: 240 seconds from the last update the route is flushed.
  • Each of these times can be manually set to achieve faster convergence times.
    • This can introduce instability if the timers are set too low.
  • All routers in the network should have the same timer settings.
  • The Update timer must be lower than the other timers.
R2(config)#router rip
R2(config-router)#timers basic 10 90 90 120

timers basic <update> <Invalid> <Hold Down> <Flush>

122. RIP Lab Demo

https://www.udemy.com/cisco-icnd1/learn/lecture/8631712#content

Initial configuration

  • No RIP or static routes configured.
  • Configure each router with the following:
configure terminal
router rip
version 2
no auto-summary
network 10.0.0.0

Configure Summarization

  • Both R2 and R5 are split between 10.0.0.0/16 and 10.1.0.0/16 so we can summarize those routes.
R2#configure terminal
R2(config)#int f0/0
R2(config-if)#ip summary-address rip 10.1.0.0 255.255.0.0
R2(config-if)#int f1/0
R2(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0

R5#configure terminal
R5(config)#int f3/0
R5(config-if)#ip summary-address rip 10.1.0.0 255.255.0.0
R5(config-if)#int f2/0
R52(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0

Inject the default route to all routers

R4#configure terminal
R4(config)#router rip
R4(config-router)#ip route 0.0.0.0 0.0.0.0 203.0.113.2
R4(config)#default-information originate

Advertise the Internet Gateway IP and disable RIP advertisement on R4-F3/0

R4#configure terminal
R4(config)#router rip
R4(config-router)#network 203.0.113.2
R4(config-router)#passive-interface f3/0

 

You are here!

RIP Configuration – Lab

https://www.udemy.com/cisco-icnd1/learn/lecture/8631720#content

19-1 RIP Configuration Lab Exercise

19-1 RIP Configuration Answer Key

1. Enable RIPv2 on every router. Ensure all networks except 203.0.113.0/24
are advertised. Do not perform any summarization.

configure terminal
router rip
version 2
no auto-summary
network 10.0.0.0

 

2. Verify all networks are in the router’s routing tables.

R5#show ip route
Gateway of last resort is not set
10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
R 10.0.0.0/24 [120/1] via 10.0.3.1, 00:00:02, FastEthernet3/0
R 10.0.1.0/24 [120/1] via 10.0.3.1, 00:00:02, FastEthernet3/0
R 10.0.2.0/24 [120/1] via 10.0.3.1, 00:00:02, FastEthernet3/0
C 10.0.3.0/24 is directly connected, FastEthernet3/0
L 10.0.3.2/32 is directly connected, FastEthernet3/0
R 10.1.0.0/24 [120/2] via 10.1.3.1, 00:00:00, FastEthernet2/0
              [120/2] via 10.0.3.1, 00:00:02, FastEthernet3/0
R 10.1.1.0/24 [120/1] via 10.1.3.1, 00:00:00, FastEthernet2/0
R 10.1.2.0/24 [120/1] via 10.1.3.1, 00:00:00, FastEthernet2/0
C 10.1.3.0/24 is directly connected, FastEthernet2/0

 

3. Enable summarization using a /16 mask on the routers which are at the
boundary of the 10.0.0.0/16 and 10.1.0.0/16 networks.

R5#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R5(config)#int f2/0
R5(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0
R5(config-if)#int f3/0
R5(config-if)#ip summary-address rip 10.1.0.0 255.255.0.0
R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#int f0/0
R2(config-if)#ip summary-address rip 10.1.0.0 255.255.0.0
R2(config-if)#int f1/0
R2(config-if)#ip summary-address rip 10.0.0.0 255.255.0.0

 

4. What change do you expect to see on R1’s routing table? Verify this (give
the routing table a couple of minutes to converge).

  • R1 will show balanced routes only to 10.1.0.0
  • Individual 10.1.x.0 routes will be removed.
R1#show ip route
Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 9 subnets, 3 masks
C 10.0.0.0/24 is directly connected, FastEthernet0/0
L 10.0.0.1/32 is directly connected, FastEthernet0/0
C 10.0.1.0/24 is directly connected, FastEthernet1/0
L 10.0.1.1/32 is directly connected, FastEthernet1/0
C 10.0.2.0/24 is directly connected, FastEthernet2/0
L 10.0.2.1/32 is directly connected, FastEthernet2/0
C 10.0.3.0/24 is directly connected, FastEthernet3/0
L 10.0.3.1/32 is directly connected, FastEthernet3/0
R 10.1.0.0/16 [120/1] via 10.0.3.2, 00:00:06, FastEthernet3/0
              [120/1] via 10.0.0.2, 00:00:01, FastEthernet0/0

 

5. Will R4’s routes to the 10.0.x.x networks mirror R1’s routes to the 10.1.x.x
networks? Verify this.

  • No. There is an administrative distance (hop count) of 2 to get to 10.0.0.0 via R4 F0/0, so the traffic will only route through F2/0.
R4# show ip route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 8 subnets, 3 masks
R 10.0.0.0/16 [120/1] via 10.1.3.2, 00:00:04, FastEthernet2/0
R 10.1.0.0/24 [120/1] via 10.1.1.2, 00:00:05, FastEthernet0/0
C 10.1.1.0/24 is directly connected, FastEthernet0/0
L 10.1.1.1/32 is directly connected, FastEthernet0/0
C 10.1.2.0/24 is directly connected, FastEthernet1/0
L 10.1.2.1/32 is directly connected, FastEthernet1/0
C 10.1.3.0/24 is directly connected, FastEthernet2/0
L 10.1.3.1/32 is directly connected, FastEthernet2/0
203.0.113.0/24 is variably subnetted, 2 subnets, 2 masks
C 203.0.113.0/24 is directly connected, FastEthernet3/0
L 203.0.113.1/32 is directly connected, FastEthernet3/0

 

6. Verify that routing is working by checking that PC1 has connectivity to
PC3.

PC1> ping 10.1.2.10
10.1.2.10 icmp_seq=1 timeout
10.1.2.10 icmp_seq=2 timeout
84 bytes from 10.1.2.10 icmp_seq=3 ttl=61 time=166.632 ms
84 bytes from 10.1.2.10 icmp_seq=4 ttl=61 time=151.071 ms
84 bytes from 10.1.2.10 icmp_seq=5 ttl=61 time=130.323 ms

 

7. Ensure that all routers have a route to the 203.0.113.0/24 network.
Internal routes must not advertised to the Service Provider at 203.0.113.2.

Routers 1, 2, 3, 5

conf t
router rip
network 203.0.113.0

Router 4

conf t
router rip
passive-interface f3/0
network 203.0.113.0

 

8. Verify that all routers have a path to the 203.0.113.0/24 network.

R2#show ip route

Gateway of last resort is not set

10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
C 10.0.0.0/24 is directly connected, FastEthernet0/0
L 10.0.0.2/32 is directly connected, FastEthernet0/0
R 10.0.1.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
R 10.0.2.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
R 10.0.3.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
C 10.1.0.0/24 is directly connected, FastEthernet1/0
L 10.1.0.2/32 is directly connected, FastEthernet1/0
R 10.1.1.0/24 [120/1] via 10.1.0.1, 00:00:07, FastEthernet1/0
R 10.1.2.0/24 [120/2] via 10.1.0.1, 00:00:07, FastEthernet1/0
R 10.1.3.0/24 [120/2] via 10.1.0.1, 00:00:07, FastEthernet1/0
R 203.0.113.0/24 [120/2] via 10.1.0.1, 00:00:07, FastEthernet1/0

R2#ping 203.0.113.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 203.0.113.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 64/79/92 ms

 

9. Configure a default static route on R4 to the Internet via the service
provider at 203.0.113.2

R4#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R4(config)#ip route 0.0.0.0 0.0.0.0 203.0.113.2
R4(config)#router rip
R4(config-router)#default-information originate

 

10. Ensure that all other routers learn via RIP how to reach the Internet.

R2#show ip route

Gateway of last resort is 10.1.0.1 to network 0.0.0.0

R* 0.0.0.0/0 [120/2] via 10.1.0.1, 00:00:04, FastEthernet1/0
10.0.0.0/8 is variably subnetted, 10 subnets, 2 masks
C 10.0.0.0/24 is directly connected, FastEthernet0/0
L 10.0.0.2/32 is directly connected, FastEthernet0/0
R 10.0.1.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
R 10.0.2.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
R 10.0.3.0/24 [120/1] via 10.0.0.1, 00:00:05, FastEthernet0/0
C 10.1.0.0/24 is directly connected, FastEthernet1/0
L 10.1.0.2/32 is directly connected, FastEthernet1/0
R 10.1.1.0/24 [120/1] via 10.1.0.1, 00:00:04, FastEthernet1/0
R 10.1.2.0/24 [120/2] via 10.1.0.1, 00:00:04, FastEthernet1/0
R 10.1.3.0/24 [120/2] via 10.1.0.1, 00:00:04, FastEthernet1/0
R 203.0.113.0/24 [120/2] via 10.1.0.1, 00:00:04, FastEthernet1/0

 

11. Verify all routers have a route to the Internet.

R2#traceroute 1.1.1.1
Type escape sequence to abort.
Tracing the route to 1.1.1.1
VRF info: (vrf in name/id, vrf out name/id)
1 10.1.0.1 16 msec 24 msec 32 msec
2 10.1.1.1 88 msec 72 msec 52 msec
3 * * *

 

12. Set the RIP timers to half their current settings on all routers.

Routers 1, 2, 3, 4 and 5

conf t
router rip
timers basic 15 90 90 120

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