Transcript Configuring RIP

CONFIGURING RIP
Routing
• There are two parts to routing IP packets:
1. How to pass a packet from an input interface to the output
interface of a router (packet forwarding) ?
2. How to find and setup a route ?
• There are two approaches for calculating the routing tables:
– Static Routing
– Dynamic Routing: Routes are calculated by a routing protocol
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Components of a Routing Algorithm
• A procedure for sending and receiving reachability information
about network to other routers
• A procedure for calculating optimal routes
– Routes are calculated using a shortest path algorithm:
• Goal: Given a network were each link is assigned a
cost. Find the path with the least cost between two
networks with minimum cost.
• A procedures for reacting to and advertising topology changes
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Approaches to Shortest Path Routing
• There are two basic routing algorithms found on the Internet.
1. Distance Vector Routing
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Each node knows the distance (=cost) to its directly connected neighbors
A node sends periodically a list of routing updates to its neighbors.
If all nodes update their distances, the routing tables eventually converge
New nodes advertise themselves to their neighbors
2. Link State Routing
• Each node knows the distance to its neighbors
• The distance information (=link state) is broadcast to all nodes in the
network
• Each node calculates the routing tables independently
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Routing Algorithms in the Internet
Distance Vector
Link State
• Routing Information Protocol
(RIP)
• Intermediate System Intermediate System (IS-IS)
• Gateway-to-Gateway Protocol
(GGP)
• Open Shortest Path First
(OSPF)
• Exterior Gateway Protocol (EGP)
• Interior Gateway Routing Protocol
(IGRP)
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A network as a graph
• In the following, networks are represented as a network
graph:
– nodes are connected by networks
– network can be a link or a LAN
– network interface has cost
– networks are destinations
– Net(v,w) is an IP address of a network
c(v,w)
Net(v,w)
• For ease of notation,
v
we often replace the
clouds between nodes
by simple links.
w
Net
c(v,n)
Net(v,n)
n
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Distance Vector Algorithm: Routing Table
c(v,w): cost to transmit on the
interface to network Net(v,w)
Net(v,w): Network address of the network between v
and w The network can be a link, but could also be a
LAN
RoutingTable of node v
Dest
v
Net(v,w)
c(v,w)
Net(v,n)
c(v,n)
via
(next hop)
cost
w
Net
Net
n
D(v,Net)
n
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Distance Vector Algorithm: Messages
RoutingTable of node v
Dest
Net
via
(next hop)
n
cost
D(v,Net)
• Nodes send messages to their neighbors which contain
routing table entries
v
[Net , D(v,Net)]
n
• A message has the format: [Net , D(v,Net)] means“My cost to
go to Net is D (v,Net)”
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RIP -- What is it?
 RIP
is a routing protocol for exchanging
routing table information between
routers.
• Routing updates must be passed between
routers so that they can make the proper
choice on how to route a packet.
RIP Characteristics
 Distance
 Uses
vector routing protocol.
hop count as a path selection
metric.
 Three
types of timers.
 Multiple
stability features.
RIP message example
RIP timers
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Periodic timer: control advertising of regular update messages (25-35
sec)
Expiration timer: governs the validity of a route (180 sec)
– Every time an update (on a 30 sec average) is received the timer is reset
– If no update received within this timer the metric is set to 16
– The maximum number of hops allowed for RIP is 15, which limits the size
of networks that RIP can support. A hop count of 16 is considered an
infinite distance and the route is considered unreachable.
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Garbage timer: 120 sec
– A route can be advertised with a 16 metric for 120 sec before it get purged
• Allow neighbors to have knowledge of the invalidity of a route
Slow Convergence Problem
Solved by limiting number of hops to 15, 16 means
That the destination is unreachable
Create a topology as
shown in figure.
Cont…
• IP RIP comes in two different versions: 1 and 2. Version 1
is a distance vector protocol. Version 2 is a hybrid
protocol. The CCNA exam now primarily focuses on
version 2. There are no major differences between RIPv1
or RIPv2 so far configurations concern.
(1841Router0) Hostname R1
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Router>enable
Router#configure terminal
Router(config)#hostname R1
R1(config)#interface fastethernet 0/0
R1(config‐if)#ip address 10.0.0.1 255.0.0.0
R1(config‐if)#no shutdown
R1(config‐if)#exit
R1(config)#interface serial 0/0/0
R1(config‐if)#ip address 20.0.0.1 255.0.0.0
R1(config‐if)#clock rate 64000
R1(config‐if)#bandwidth 64
R1(config‐if)#no shutdown
R1(config‐if)#exit
R1(config)#router rip
R1(config‐router)#network 10.0.0.0
R1(config‐router)#network 20.0.0.0
R1(config‐router)#exit
(2620XMRouter1)
Hostname R2
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Router>enable
Router#configure terminal
Router(config)#hostname R2
R2(config)#interface serial 0/0
R2(config‐if)#ip address 20.0.0.2 255.0.0.0
R2(config‐if)#no shutdown
R2(config‐if)#exit
R2(config)#interface fastethernet 0/0
R2(config‐if)#ip address 30.0.0.1 255.0.0.0
R2(config‐if)#no shutdown
R2(config)#router rip
R2(config‐router)#network 20.0.0.0
R2(config‐router)#network 30.0.0.0
R2(config‐router)#exit
R2(config)#
(2620XMRouter2)
Hostname R3
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Router>enable
Router#configure terminal
Router(config)#hostname R3
R3(config)#interface fastethernet 0/0
R3(config‐if)#ip address 30.0.0.2 255.0.0.0
R3(config‐if)#no shutdown
R3(config‐if)#interface serial 0/0
R3(config‐if)#ip address 40.0.0.1 255.0.0.0
R3(config‐if)#clock rate 64000
R3(config‐if)#bandwidth 64
R3(config‐if)#no shutdown
R3(config‐if)#exit
R3(config)#router rip
R3(config‐router)#network 30.0.0.0
R3(config‐router)#network 40.0.0.0
R3(config‐router)#exit
R3(config)#
(2811Router3) Hostname R4
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Router>enable
Router#configure terminal
Router(config)#interface serial 0/0/0
Router(config‐if)#ip address 40.0.0.2 255.0.0.0
Router(config‐if)#no shutdown
Router(config‐if)#exit
Router(config)#interface fastethernet 0/0
Router(config‐if)#ip address 50.0.0.1 255.0.0.0
Router(config‐if)#no shutdown
Router(config‐if)#exit
R4(config)#router rip
R4(config‐router)#network 40.0.0.0
R4(config‐router)#network 50.0.0.0
R4(config‐router)#exit
R4(config)#
PC1
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PC>ipconfig
IP Address......................:
10.0.0.2
Subnet Mask.....................:
255.0.0.0
Default Gateway.................:
10.0.0.1
PC>ping 50.0.0.2
You can verify that RIP is running successfully via
show ip protocols command in privilege mode
• R1#show ip protocols
• R1#show ip route