ccna chapter 6 by jetarvind kumar madhukar
TRANSCRIPT
Release 16/07/2009 Jetking Infotrain Ltd.
Chapter Objectives
Explain Protocols Explain Routing Metrics Discuss Routing Mechanisms Explain Routing Algorithms Set up routing
Release 16/07/2009 Jetking Infotrain Ltd.
Recall
The router configuration files are located in: RAM NVRAM TFTP Server
Protocol that gives the information about locally attached and remote devices in the network is termed as Cisco Discovery Protocol (CDP)
CDP global parameters include: CDP timer CDP holdtime
Release 16/07/2009 Jetking Infotrain Ltd.
Goals of Routing
Routing process ensures that appropriate packets are routed from the source to the destination
Goals of routing include: Stability Provides with a robust network Dynamic update of the network paths Information is safe while transmitting
Release 16/07/2009 Jetking Infotrain Ltd.
Routing Metrics
Routing metrics are values that allow the routers decide the best route for the data packet
Different routing metrics include: Hops Bandwidth Load Cost Reliability
Release 16/07/2009 Jetking Infotrain Ltd.
Dynamic Routing
The phenomena in which the routing protocols are assigned the job of finding the path to route the packets and update the routing tables
Two types of dynamic routing protocols include: Interior routing protocols Exterior routing protocols
Release 16/07/2009 Jetking Infotrain Ltd.
Administrative Distance
An integer assigned to every routing protocol, which determines the reliability of the routing protocol is termed as administrative distance (AD)
The integer is in the range of 0 to 255 Lower the AD, more reliable is the routing
information provided by the routing protocol
Release 16/07/2009 Jetking Infotrain Ltd.
AD of Routing Protocols
Routed Source Default AD
Connected Interface 0
Static Route 1
Enhanced Interior Gateway Routing Protocol (EIGRP)
90
Interior Gateway Routing Protocol (IGRP) 100
Open Shortest Path First (OSPF) 110
Routing Information Protocol (RIP) 120
External EIGRP 170
Unknown 255 (This route will never be used)
Release 16/07/2009 Jetking Infotrain Ltd.
Interior Routing Protocols
The protocols used to route the packets inside an autonomous system, are termed as Interior Routing protocols
Interior routing protocols include: Routing Information Protocol (RIP) Open Shortest Path First (OSPF) Interior Gateway Routing Protocol (IGRP) Enhanced Interior Gateway Routing Protocol
(EIGRP) Intermediate System to Intermediate System (IS – IS)
Release 16/07/2009 Jetking Infotrain Ltd.
Exterior Routing Protocols
The routing protocols that communicate between the two or more Autonomous Systems (AS) are termed as Exterior routing protocols
Exterior Routing Protocols include: Exterior Gateway Protocols (EGP) Border Gateway Protocol (BGP)
Release 16/07/2009 Jetking Infotrain Ltd.
Routing Tables The routing tables then decide the best path to the
route the packet, which also includes the next hop address
Information contained in the routing table include: Destination Next hop address Outgoing interface Routing Protocols
Release 16/07/2009 Jetking Infotrain Ltd.
Static Routing
The phenomena of adding routes manually to the routing table, is termed as static routing
This is feasible in small networks, but not in large networks
Release 16/07/2009 Jetking Infotrain Ltd.
Routing Information Protocol (RIP)
RIP allows routers to exchange their routing tables at a predefined interval
Characteristics of RIP include: Uses hop count metric Supports 15 hop-count limit Supports six equal-cost paths
Release 16/07/2009 Jetking Infotrain Ltd.
Distance Vector concept
The routers connected to the neighboring networks update the list of networks and the hop counts in the routing table
The connected routers update the routing table with the network information
The routers connected to the distant networks construct a new routing table
The network information of the connected routers combined with the new routing table entries is passed to all the neighboring routing tables
Release 16/07/2009 Jetking Infotrain Ltd.
RIP Timers
RIP timers are used to keep a track of the various routes connected
The different RIP timers include: Route update timer Route invalid timer Holddown timer Route Flush timer
Release 16/07/2009 Jetking Infotrain Ltd.
Enhancements in RIPv2
RIPv2 was created to overcome the drawbacks of RIPv1
RIPv2 enhancements include: Multicasting Triggered updates Classless protocol Authentication
Release 16/07/2009 Jetking Infotrain Ltd.
Case Study
The Hyderabad branch of the Blue Diamond Steel Company has 10 routers connected in the network. Initially, the network administrator had configured the network to use static routes to route the packets containing the data and to communicate between the networks. Now the company has decided employ more than 100 employees for their operations in Software Management, Human Resource, Detailing, Business Development and Sales. This requires the company to add five more networks to the existing ones.
Release 16/07/2009 Jetking Infotrain Ltd.
Problem
The network administrator has to manually add routes to all the networks connected and then
send the packets
Release 16/07/2009 Jetking Infotrain Ltd.
Solution
The network administrator decided to use RIP, which is a dynamic routing protocol. It can add the routes to the network automatically and uses hop count as its metric to route the packets and can be used to
connect small networks
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - I
Routing occurs at the network layer of the OSI model
Protocols are a set of rules that define data transfer The routing protocols can be classified based on
their routing abilities as: Interior Routing Protocols Exterior Routing Protocols
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - II
Interior Routing protocols can be classified as: Routing Information Protocol (RIP) Open Shortest Path First (OSPF) Interior Gateway Routing Protocol (IGRP) Enhanced Intermediate System to Intermediate
System (EIGRP) Intermediate System to Intermediate System
Exterior Routing protocols can be classified as: Exterior Gateway Protocol (EGP) Border Gateway Protocol (BGP)
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - III
Routing metrics are cost values that enable routers decide the best route for the data packet
When a router forwards a data packet to a network segment, it is counted as a single hop
Bandwidth measures the amount of data that can travel over the network segment in a fixed amount of time
Delay specifies the amount of time that a router takes to process and transfer a data packet to the next device on the network
The delay is represented with a µ symbol
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - IV
Load refers to the amount of traffic on a particular link relative to the total capacity of the link
The load value 255 indicates 100% traffic congestion Direct interfaces consist of routes that are local to the
router Routed protocols consist of protocols that define
routing and addressing Routing protocols are a set of rules that are
implemented on a router to determine the best path to route the packets
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - V
Routing protocols can be classified into Interior Routing Protocols and Exterior Routing Protocols
Every router has a routing table based on which the data packets are forwarded to the destinations
Static routes are the routes that the administrator manually enters in the routing table
Static routes are used in temporary connections such as dial-up networks
The router automatically collects and stores dynamic routes in the routing table
Release 16/07/2009 Jetking Infotrain Ltd.
Summary - VI
Enhancements in RIPv2 include: Supports multicast updates against broadcast
updates Uses triggered updates to share its routing
information with the neighbors, when a change occurs
Supports Variable-Length Subnet Masking (VSLM)
Allows you to select the routers you want to participate in RIPv2