CCNA3 Chapter 1 Introduction to Classless RoutingCISCO NETWORKING ACADEMY PROGRAM
Introduction to Classless Routing
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Introduction to Classless Routing
Variable Length Subnet Masks
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Classful Routing
Limited Number of unique network addresses
Complex Routing tables
No subnet information sent in routing updates by classful routing protocols e.g. RIP v1, IGRP
CCNA3: Switching Basics and Intermediate Routing v3.0
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Problem 1a
FSF Ltd has been allocated a class C address
It has 3 branch offices with a requirement of 10 hosts per network connecting via point to point links to the Head Office with 25 hosts
Design a subnet mask for FSF
Head Office
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Problem 1b
Head Office (25 hosts)
CCNA3: Switching Basics and Intermediate Routing v3.0
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Problem 1b continued
Variable Length Subnet Mask
Use 27 bit mask for head office (5 host bits = 32 hosts)
Use 28 bit mask for branch offices (4 host bits = 16 hosts)
Use 30 bit mask for router to router links (2 host bits = 4 hosts)
Using 192.168.200.0 write out the addressing scheme for this network
CCNA3: Switching Basics and Intermediate Routing v3.0
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Problem 2
Most class A & B network addresses allocated
PHS Ltd with 800 hosts wants IP addresses for its network
4 different Class C network addresses needed
4 routing table entries for that network
CCNA3: Switching Basics and Intermediate Routing v3.0
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Solution 2 – Part 1
Routing table entry for PHS is
212.23.24.0 /22 OR
11111111.11111111.11111100.00000000
This mask groups 4 class C networks into 1 network & routing table entry
CCNA3: Switching Basics and Intermediate Routing v3.0
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Solution 2 – Part 2
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Problem 3
PHS Ltd has 4 class C address blocks allocated
It does not want to waste the addresses it has been given
The network administrator has the following requirements based on current use & future growth needs
Head Office - 500 hosts Factory - 50 hosts
Logistics Centre – 80 hosts Customer support Centre – 220 hosts
Question:
What is the appropriate VLSM mask solution for PHS Ltd?
CCNA3: Switching Basics and Intermediate Routing v3.0
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Solution 3 (example)
List the addresses
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Requirements for classless routing
Contiguous network addresses to allow route aggregation
CCNA3: Switching Basics and Intermediate Routing v3.0
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Introduction to Classless Routing
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RIP Version 1 Review
Supported by most routers
Distance Vector routing protocol
Uses holddown timers
Does not support authentication
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RIP v2 enhancements
Supports authentication
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IOS RIP v2 Command
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Verifying Routing Protocols
Router#show ip protocols
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Configuring Routes
Static Routes
ip route destination network gateway
Default Route
Defines the default gateway for all routes
Keeps routing tables small
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Default Network
1 router on a network must have a default route on the network e.g.
Router#ip route 0.0.0.0 0.0.0.0 192.168.1.1
Other routers can have a default network set
Router#ip default network 192.168.1.0
Traffic for destinations outside of the LAN will be sent to the router with the network address 192.168.1.0
CCNA3: Switching Basics and Intermediate Routing v3.0
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Labs
1.2.4 Converting RIP v1 to RIP v2
1.2.5 Verifying RIP v2 Configuration
1.2.6 Troubleshooting RIP v2 using Debug