Download rip_igrp_notes

Summer Youth Program:
Internal Protocols:
RIP & IGRP
CNSA Department
SYP
2007
What is Routing?
To route a router need to know:
– Remote Networks
– Neighbor Routers
– All Possible routes to remote network
– The absolute best route to all remote networks
– Maintain and verify the routing information
D
CNSA Department
C
SYP
B
A
2007
Basic Path Selection
What interface will the router send out a packet if it
has destination address of 10.10.10.18?
CNSA Department
SYP
2007
Basic IP Routing
>ping 172.16.1.2
172.16.2.0
172.16.1.0
172.16.3.1 172.16.3.2
e0
e0
172.16.2.2
Host A
172.16.2.1
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A
B
s0
s0
B
172.16.1.1
SYP
172.16.1.2
Host B
2007
Routing/PDU Example:
Host A Web browses to the HTTP
Server….
1. The destination address of a frame will be the _______________________
2. The destination IP address of a packet will be the IP address
of the ________________________________
3. The destination port number in a segment header will have a value of __
CNSA Department
SYP
2007
Routing/PDU Example:
Host A Web browses to the HTTP
Server….
1. The destination address of a frame will be the Ethernet 0 on Lab A
2. The destination IP address of a packet will be the IP address
of the NIC of the HTTP server
3. The destination port number in a segment header will have a value of 80
CNSA Department
SYP
2007
Static Routes
Stub Network
172.16.1.0
172.16.2.0
SO
AA
SO
172.16.3.1
172.16.3.2
B
B
Routes must be unidirectional
CNSA Department
SYP
2007
Static Route Configuration
ip route remote network
[mask]
{address|interface}
[distance]
[permanent]
Router(config)#ip route remote_network mask next_hop
CNSA Department
SYP
2007
Static Route Example
Stub Network
172.16.2.0
172.16.1.0
SO
SO
A
172.16.3.1
172.16.3.2
B
B
ip route 172.16.1.0 255.255.255.0 172.16.3.2
or
ip route 172.16.1.0 255.255.255.0 s0
CNSA Department
SYP
2007
Default Routes
Stub Network
172.16.1.0
172.16.2.0
SO
SO
A
172.16.3.1
172.16.3.2
B
B
ip route 0.0.0.0 0.0.0.0 172.16.3.1
ip classless
CNSA Department
SYP
2007
Routing vs. Routed
• Routing protocols are used between routers to:
– Determine the path of a packet through a network
– Maintain routing tables
– Examples?
• Routed protocols are:
– Assigned to an interface
– Once the path is determined by the Routing protocol, determines
method of delivery
– Examples?
CNSA Department
SYP
2007
Routing Protocols
IGPs: RIP, IGRP
EGPs: BGP
Autonomous System 1
Autonomous System 2
• An autonomous system is a collection of networks under a
common administrative domain.
• IGPs operate within an autonomous system.
• EGPs connect different autonomous systems.
CNSA Department
SYP
2007
Classful Routing Overview
Classful routing protocols do not
include the subnet mask with the
route advertisement.
– Within the same network, consistency of the subnet
masks is assumed.
– Summary routes are exchanged between foreign
networks.
– Examples of classful routing protocols:
• RIP Version 1 (RIPv1)
• IGRP
CNSA Department
SYP
2007
Classless Routing Overview
Classless routing protocols include the
subnet mask with the route
advertisement.
– Classless routing protocols support variable-length subnet
masking (VLSM).
– Summary routes can be manually controlled within the
network.
– Examples of classless routing protocols:
• RIP Version 2 (RIPv2)
• EIGRP
• OSPF
• IS-IS
CNSA Department
SYP
2007
Administrative Distance
Router B
Router A
RIP
Administrative
Distance=120
IGRP
Administrative
Distance=100
Router C
Router D
Default Administrative Distance
Directly Connected: 0
Static Route: 1
RIP: 120
IGRP: 100
EIGRP: 90
OSPF: 110
CNSA Department
SYP
2007
Distance Vector
Distance—How far
Vector—In which direction
D
Routing
Table
C
B
A
Routing
Table
Routing
Table
Routing
Table
Distance vector algorithms do not allow a router to
know the exact topology of an internetwork.
All routers just broadcast their entire routing table out
all active interfaces on periodic time intervals
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2007
Discovering Routes
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2007
Routing Tables Populated
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2007
Routing Loops
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2007
Router Loops
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2007
RIP Overview
64kbps
T1
T1
T1
–
–
–
–
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Hop count metric selects the path, 16 is unreachable
Full route table broadcast every 30 seconds
Load balance maximum of 6 equal cost paths (default = 4)
RIPv2 supports VLSM and Discontiguous networks
SYP
2007
RIP Routing Configuration
Router(config)#router rip
Router(config-router)#network network-number*
10.3.5.0
192.168.10.0
172.16.10.0
router RIP
router RIP
network 172.16.0.0
network 10.0.0.0
network 172.16.0.0
network 192.168.10.0
*Network is a classful network address.
Every device on network uses the same subnet mask
CNSA Department
SYP
2007
RIP Version 2
• Allows the use of variable length subnet masks
(VLSM) by sending subnet mask information
with each route update
• Distance Vector – same AD, and timers.
• Easy configuration, just add the command
“version 2” under the router rip configuration
router rip
network 10.0.0.0
version 2
CNSA Department
SYP
2007
Discontiguous Addressing
• Two networks of the same classful networks are
separated by a different network address
192.168.10.0/24
192.168.10.0/24
10.1.1.0/24
– RIPv1 and IGRP do not advertise subnet masks, and therefore
cannot support discontiguous subnets.
– OSPF, EIGRP, and RIPv2 can advertise subnet masks, and
therefore can support discontiguous subnets.
CNSA Department
SYP
2007
Passive Interface
Maybe you don’t want to send RIP updates
out your router interface connected to the
Internet. Use the passive-interface
command:
Router(config)#router rip
Router(config-router)#passive-interface serial0
Internet
X
S0
Updates
Gateway
This allows a router to receive route updates on an interface,
but not send updates via that interface
CNSA Department
SYP
2007
Verifying RIP
Router#show ip protocols
Router#show protocols
Router#show ip route
Router#debug ip rip
Router#undebug all (un all)
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SYP
2007
IGRP
• Interior Gateway Routing Protocol - Cisco Proprietary
• Uses bandwidth and delay of the line by default to select best path
Router A
Router B
Autonomous
System
Router C
Router D
Requires Autonomous System number for activation
CNSA Department
SYP
2007
IGRP vs. RIP
• The important IGRP characteristics are as
follows:
–
–
–
–
More scalability than RIP
Fast response to network changes
Sophisticated metric
Multiple-path support
CNSA Department
SYP
2007
Configuring IGRP
Router(config)#router igrp autonomous-system
Router(config-router)#network network-number*
10.3.5.0
172.16.10.0
router IGRP 10
network 172.16.0.0
network 10.0.0.0
192.168.10.0
router IGRP 10
network 172.16.0.0
network 192.168.10.0
*Network is a classful network address.
Every device on network uses the same subnet mask
CNSA Department
SYP
2007
Verifying IGRP
Router# show ip route
Router# show ip protocols
Router# debug ip igrp transaction
Router# debug ip igrp events
Router# undebug all (un all)
CNSA Department
SYP
2007