Introduction to Classless Routing VLSM RIP Version 2

Introduction to Classless Routing Variable Length Subnet Masks

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

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

Problem 1b FSF Ltd plans 3 additional branch offices (10 hosts per LAN) Head Office (25 hosts) Design a new subnet mask

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

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

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

Solution 2 – Part 2 11010100.00010111.00011000.00000000 (Network) 11111111.11111111.11111100.00000000 (Mask) 128 64 32 16 8 4 2 1 24 128 64 32 16 8 4 2 1 25 128 64 32 16 8 4 2 1 26 128 64 32 16 8 4 2 1 27

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?

Solution 3 (example) List the addresses On interfaces On each site Still available Head Office Logistics Customer Services Factory Internet 212.23.24.0 /22 212.23.27.0 /30 212.23.27.8 /30 212.23.27.4 /30 212.23.24.0 /23 212.23.26.0 /24 212.23.27.64 /26 212.23.27.128 /25

Requirements for classless routing Classless routing protocol e.g. EIGRP, OSPF, RIP v2 Contiguous network addresses to allow route aggregation

Introduction to Classless Routing RIP Version 2

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

RIP v2 enhancements Sends subnet information in updates – supports CIDR & VLSM Supports authentication Updates multicast to 224.0.0.9

IOS RIP v2 Command Enable RIP v2 Router(config)#router rip Router(config-router)#version 2 Router(config-router)#network 10.0.0.0

Verifying Routing Protocols Check the configuration of routing protocols Router#show ip protocols Router#show running-config Viewing RIP updates Router#debug ip rip

Configuring Routes Static Routes Default Route 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

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

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