CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Introduction to Classless Routing
VLSM
RIP Version 2
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Introduction to Classless Routing
Variable Length Subnet Masks
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Classful Routing
•
•
•
•
IP Version 4 provides Classes A, B, C
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
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
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
Chapter 1 – Introduction to Classless Routing
Head
Office
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Problem 1b
• FSF Ltd plans
• 3 additional branch offices
(10 hosts per LAN)
• Head Office (25 hosts)
• Design a new subnet mask
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
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
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
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
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Solution 2 – Part 1
• ISP allocates 212.23.24.0 to 212.23.27.255
• Routing table entry for PHS is
– 212.23.24.0 /22 OR
– 212.23.24.0 255.255.252.0
• 22 bit mask in binary:
– 11111111.11111111.11111100.00000000
• This mask groups 4 class C networks into 1
network & routing table entry
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Solution 2 – Part 2
– 11010100.00010111.00011000.00000000 (Network)
– 11111111.11111111.11111100.00000000 (Mask)
128
64
32
16
8
4
2
1
0
0
0
1
1
0
0
0
128
64
32
16
8
4
2
1
0
0
0
1
1
0
0
1
128
64
32
16
8
4
2
1
0
0
0
1
1
0
1
0
128
64
32
16
8
4
2
1
0
0
0
1
1
0
1
1
Chapter 1 – Introduction to Classless Routing
24
25
26
27
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
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
Logistics Centre – 80 hosts
Factory - 50 hosts
Customer support Centre – 220 hosts
Question:
What is the appropriate VLSM mask solution for PHS Ltd?
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Solution 3 (example)
List the addresses
Internet
212.23.24.0 /23
212.23.24.0 /22
1.
2.
3.
Head Office
212.23.27.0 /30
212.23.27.8 /30
212.23.27.4 /30
Customer
Services
212.23.26.0 /24
Factory
212.23.27.64 /26
Chapter 1 – Introduction to Classless Routing
Logistics
212.23.27.128 /25
On interfaces
On each site
Still available
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Requirements for classless routing
• Classless routing protocol e.g. EIGRP, OSPF,
RIP v2
• Contiguous network addresses to allow route
aggregation
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Introduction to Classless Routing
RIP Version 2
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
RIP Version 1 Review
•
•
•
•
•
•
•
•
•
Supported by most routers
Distance Vector routing protocol
Metric – hop count
15 hop maximum count
Periodic routing updates (30 seconds)
Routing updates broadcast to 255.255.255.255
Uses holddown timers
Does not send subnet information in updates
Does not support authentication
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
RIP v2 enhancements
• Sends subnet information in updates – supports
CIDR & VLSM
• Supports authentication
• Updates multicast to 224.0.0.9
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
IOS RIP v2 Command
•
Enable RIP v2
Router(config)#router rip
Router(config-router)#version 2
Router(config-router)#network 10.0.0.0
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Verifying Routing Protocols
• Check the configuration of routing protocols
Router#show ip protocols
Router#show running-config
• Viewing RIP updates
Router#debug ip rip
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Configuring Routes
• Static Routes
Router(config)#ip route 192.168.2.0
255.255.255.0 192.168.1.1
ip route destination network gateway
Default Route
Router#ip route 0.0.0.0 0.0.0.0 192.168.1.1
• Defines the default gateway for all routes
• Keeps routing tables small
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
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
Chapter 1 – Introduction to Classless Routing
CISCO NETWORKING ACADEMY PROGRAM
CCNA3: Switching Basics and Intermediate Routing v3.0
Labs
•
•
•
•
•
1.1.4 Calculating VLSM Subnets
1.2.3 Review of Basic Router Configuration with RIP
1.2.4 Converting RIP v1 to RIP v2
1.2.5 Verifying RIP v2 Configuration
1.2.6 Troubleshooting RIP v2 using Debug
Chapter 1 – Introduction to Classless Routing