Cisco Systems Networking AcademyS2 C 12

Routing Protocols

Setup Mode

• Initial Configuration– No valid startup-config

– System load ends with setup mode

– Use system configuration dialogue to setup• Result is minimal-feature router configuration

• Can configure later to add protocol and interface changes– Minimal contains inventory of interfaces, opportunity to enter

global parameters, opportunity to enter interface parameters, setup script, opportunity to accept configuration

» Whey you answer YES, it becomes running configuration

» Configure allows you to enter additional commands

Initial Setup

• Each interface must be configures with an IP address and a mask– Set static routes

• Point-to-point

• Stub networks

– Set Default routes• No router table entry for destination network

– Set Dynamic routes• Router learns paths by receiving period updates from other

routers

IP Route Command

• Requires– Network destination network– Mask subnet mask– Address IP address of next-hop router– Interface name of interface to use to get to

destination network– Distance Administrative distance – value

to help determine best path- low is good (trustworthiness 0-255)

Using IP Route Command

• IP route 172.11.1.0 255.255.255.0 172.11.2.1– Specifies static route to subnet

– Subnet mask in effect

– IP address of next-hop router in path to destination

• LAB– Configure a static route between neighboring routers

Default Network

• Router (config)# ip default-network 172.22.22.1– Configures default network

• Requires additional command– Redistribute static

• S0 all networks have knowledge of the candidate default network

Sample Commands

• Router (config)# router rip

• Router (config)# network 145.45.3.0

• Router (config)# network 191.23.21.0

• Router (config)# default-network 154.44.1.0

Autonomous System

• A routing protocol such as Cisco's IGRP requires that you specify this unique, assigned autonomous system number in your configuration.

• The Network Information Center (NIC) assigns a unique autonomous system to enterprises.

Autonomous Systems

• Interior Routing Protocols– Used within autonomous system

• RIP, IGRP, EIGRP, OSPF

• Exterior Routing Protocols– Used between autonomous systems

• BGP (Border Gateway Protocol)

• EGP (Exterior Gateway Protocol)

Global Configuration

• Select routing protocol (s)• Specify network (s)

– Router(config)# router rip• An option could be autonomous number

– Router(config-router)# 172.34.3.0• Specifies a directly connected router

• Interface Configuration– Verify address/subnet mask

RIP

• Specified in RFC 1058– Distance vector– Hop count is metric– Max is 15; over 15 will discard packet– Routing updates broadcast every 30 seconds

• In RIP all subnet masks must be the same. RIP does not share subnetting information in routing updates.

Show IP Protocol

• Displays values, about routing timers and network information, that are associated with the entire router– Shows protocol, how often updated, next

update due time, hold down, routing for all networks, gateways, distances and last update

– Administrative distance – default 120

Show IP Route

• Lets you examine the contents of the routing table

• Essential (for troubleshooting why the router may be dropping or incorrectly routing packets

• Contains entries for all known networks and subnetworks with a code that shows how information was learned

IGRP

• Distance-vector router protocol – Cisco

• Sends updates every 90 seconds– Handles indefinite, complex topologies– Flexible for different bandwidth & delay– Scalable for functioning in large networks– Composite metric

• Bandwidth, delay, load, reliability

• Speed is primary consideration

Enable IGRP

• Router (config) # router igrp autonomous-system

• Selects IGRP as routing protocol

• Router (config-router)# network network #• Identifies connected network

• Like RIP, all subnet masks must be the same – does not share subnetting information in routing updates

Sample Commands

• Router (config) # router igrp 109– Selects igrp as routing protocol for network 109

• Router (config-router)# network 1.0.0.0– Specifies directly connected networks

Show IP Protocol

• Router # show ip protocol– Identifies protocol– Show algorithm used to calculate metric– Shows update period and next due update– Shows hold down period– Shows networks routed– Shows routing information source

Show ip interface

Router > show ip interface

Displays status and global parameters associated with all IP interfaces

Cisco IOS enters route in routing table if interface can send and receive – marked up

Unusable interfaces are removed from table

Display from show ip interface

Internet Address and subnet mask & broadcast address

Access lists if any

Security level

Split horizon (enabled) or not

Other features enables or disabled

Show IP Route

• Examine contents of routing table

• Troubleshoot why packets are dropped or incorrectly routed

• Tables contains all known networks and subnets and metrics

• Shows how information was learned

• Shows if network is connected

Debug ip rip

• Powerful but bandwidth intensive• Allow real time examination of routing updates• Displays routing updates as they are sent and

received• Can decrease network performance and cause loss

or connectivity – use only during times of low network usage

• No debug ip rip• No debug all

Lab

• Use Cisco commands learned to date– Loops

• Hold-down timers, max hop count, counting to infinity, poison reserve and split horizon

– DCE connection– Interfaces

• Configure entire 5-router network

• Troubleshoot problems