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Intro to Cisco Routers and
RIP & IGRP
Lecture 6
Hassan Shuja
04/18/2006
Page 1
Cisco Routers
• SOHO, Branch Office, Central Site
– Different size sites will have different requirements
– Review handout to determine proper router for each type of site
– Some of the determining factors in selecting a router are cost, availability,
throughput, and additional features
– Service Providers (ISP) have a different line of routers available to them
Page 2
Cisco Routers
• SOHO, Branch Office, Central Site
– Cisco has added the 800, 1800, 2800, and 3800 Integrated Service
routers
– http://cisco.com/en/US/products/hw/routers/products_category_buyers_guide.html
– Integrated routers allow one box to be the router, security device, VPN
Gateway, WAP, Switch, IP Telephony Call Manger, etc…
Page 3
RIP & IGRP
• Routing Information Protocol (RIP)
– RIP updates are sent every 30 seconds
– A router updates its routing table once it receives an update and increments
the path metric to the destination network by 1
– RIP only maintains the best path to the remote network which is based on
hop metric
– Could case unoptimal paths
– Routing updates are sent independently of the regularly scheduled updates
– RIP is very easy to configure
– RIP does not support VLSM
• RIP Metric
– RIP only uses the hop count metric
– Each hop has a value of 1
– The maximum number of hops allowed in a path are 15
– If a router receives an update that increases the metric for a network to be 16
then that network is considered to be unreachable
Page 4
RIP & IGRP
• RIP Configuration
– RIP only requires two commands to be enabled
Command
Configuration Mode
router rip
Global
network network -number Router subcommand
– Example:
130.85.5.1
10.1.2.3
199.20.3.1
Router(config)#router rip
Router(config-router)#network 199.20.3.0
Router(config-router)#network 10.0.0.0
Router(config-router)#network 130.85.0.0
Page 5
RIP & IGRP
• Interior Gateway Routing Protocol (IGRP)
– IGRP was developed by Cisco in the mid 80s
– The goal was to provide a robust routing protocol with an autonomous
system
– Autonomous system is collection of networks under a common administration
sharing a common routing strategy
– Can also be thought of as a routing domain
– IGRP uses a metric that factors delay, bandwidth, reliability, and load
– Network administrators can change these values and influence route
selection
– Bandwidth metric is set on the specific interface
– IGRP permits multipath routing
– IGRP does not support VLSM
Page 6
RIP & IGRP
• IGRP Configuration
– IGRP only requires two commands to be enabled
Command
Configuration Mode
router rip
Global
network network -number Router subcommand
– Example:
130.85.5.1
10.1.2.3
199.20.3.1
Router(config)#router igrp 5
Router(config-router)#network 199.20.3.0
Router(config-router)#network 10.0.0.0
Router(config-router)#network 130.85.0.0
Page 7
RIP & IGRP Testing
• Ping
– The ping command sends an ICMP echo request packet to the destination
address
– The destination responds back with an echo reply ICMP packet
– The Ping command sends the first packet and waits for the response
–
–
–
–
If a response is received a “!” is displayed
If no response is received a “.” is displayed
The default timeout is 2 seconds
Cisco IOS sends 5 packets by default
• Extended Ping
– Allows you to change the default ping packet settings
– Most importantly allows you to specific which interface to use as the source
when sending the ping packet
– It allows you to also change the following things
– Packet size, timeout, number of packets sent
Page 8