Cisco Systems OL-31454-01 manual Default Routes, Default Network, Gateway of Last Resort

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Chapter 4 Configuring the Router

Performing the Initial Configuration on the Router

Default Routes

A router might not be able to determine the routes to all other networks. To provide complete routing capability, the common practice is to use some routers as smart routers and give the remaining routers default routes to the smart router. (Smart routers have routing table information for the entire internetwork.) These default routes can be passed along dynamically, or can be configured into the individual routers.

Most dynamic interior routing protocols include a mechanism for causing a smart router to generate dynamic default information that is then passed along to other routers.

Default Network

If a router has an interface that is directly connected to the specified default network, the dynamic routing protocols running on the router generates or sources a default route. In the case of RIP, the router advertises the pseudonetwork 0.0.0.0. In the case of IGRP, the network itself is advertised and flagged as an exterior route.

A router that is generating the default for a network also may need a default of its own. One way a router can generate its own default is to specify a static route to the network 0.0.0.0 through the appropriate device.

Gateway of Last Resort

When default information is being passed along through a dynamic routing protocol, no further configuration is required. The system periodically scans its routing table to choose the optimal default network as its default route. In the case of RIP, there is only one choice, network 0.0.0.0. In the case of IGRP, there might be several networks that can be candidates for the system default. The Cisco IOS software uses both administrative distance and metric information to determine the default route (gateway of last resort). The selected default route appears in the gateway of last resort display of the show ip route EXEC command.

If dynamic default information is not being passed to the software, candidates for the default route are specified with the ip default-networkglobal configuration command. In this usage, the ip default-networkcommand takes an unconnected network as an argument. If this network appears in the routing table from any source (dynamic or static), it is flagged as a candidate default route and is a possible choice as the default route.

If the router has no interface on the default network, but does have a route to it, it considers this network as a candidate default path. The route candidates are examined and the best one is chosen, based on administrative distance and metric. The gateway to the best default path becomes the gateway of last resort.

SUMMARY STEPS

1.enable

2.configure terminal

3.ip routing

4.ip route dest-prefix mask next-hop-ip-address [admin-distance] [permanent]

5.ip default-network network-numberor

ip route dest-prefix mask next-hop-ip-address

 

 

Cisco 2010 Connected Grid Router Hardware Installation Guide

 

 

 

 

 

 

OL-31454-01

 

 

4-15

 

 

 

 

 

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Contents Cisco 2010 Connected Grid Router Hardware Installation Guide Page N T E N T S Attaching Rack-Mount Brackets to Cisco CGR 2010 Routers Configuring the Router Verifying the Initial Configuration Audience ObjectivesConvention Indication OrganizationConventions Chapter Title DescriptionBewaar Deze Instructies Avvertenza Importanti Istruzioni Sulla Sicurezza Warnung Wichtige SicherheitshinweiseAviso Instruções Importantes DE Segurança Spara Dessa Anvisningar GEM Disse Anvisninger Xiii Xiv Searching for Cisco Documents Obtaining Documentation and Submitting a Service RequestXvi A P T E R Chassis ViewsOverview of the Router Hardware Features Hardware FeaturesDo not Remove During Network Operation Locating Chassis Features and FunctionsAUX Grwic Installation OptionsSFP Ports Built-in Interface PortsGigabit Ethernet Ports Gigabit Ethernet PortsUSB Console Port Removable and Interchangeable Modules and CardsGrid Router WAN Interface Cards Hot Swap Internal RPS1 Dual DC2 Power SuppliesMemory Model DescriptionPSU 1 OK LED LED IndicatorsSlot, Port, and Interface Information Real-Time ClockSYS Color DescriptionUSB CON ACTPSU Console ENSlot SpecificationsGE 0/0 Link OL-31454-01 Preparing for Router Installation Safety Recommendations Preventing Electrostatic Discharge Damage Safety with ElectricityRack Requirements General Site RequirementsRouter Environmental Requirements Console Port Connections Power Guidelines and RequirementsNetwork Cabling Specifications Console and Auxiliary Port ConsiderationsAuxiliary Port Connections Preparing for Network ConnectionsUSB Serial Console Port Serial DTE or DCE Devices Configuring Serial ConnectionsEthernet Connections Serial ConnectionsDistance Limitations Signaling Standards SupportedDevice Type Gender Typical Devices 56000 102 16.4 1544000 T1 Asynchronous/Synchronous Serial Module Baud RatesCreating a Site Log Installation ChecklistTask Verified by Date Preparing for Router Installation Creating a Site Log OL-31454-01 Installing and Connecting the Router OL-31454-01 What you Need to Know CLI Console AccessSlot and Port Numbers Unpacking the Router Before You BeginRack-Mounting the Chassis Installing the Router in a RackCisco CGR 2010 router can only be mounted in a rack PSU OK PWR-150W-HV Attaching Rack-Mount Brackets to Cisco CGR 2010 RoutersMounting screws Mounting the Router in a RackConnecting AC Power Power-Supply ModulesModel Description Voltage Range Power-Input Terminal Designations Using Tie Wraps with the Strain Relief Mechanism Connecting AC PowerConnecting DC Power 10 Stripping the Input Power Source Wire Connecting DC Power 11 Using Tie Wraps with the Strain Relief Mechanism Protecting the Terminal Block from Exposure 12 CGR 2010 Power Terminal CoverReplacing Power Supplies and Redundant Power Supplies Shutting Off PowerReplacing the Cisco CGR 2010 Router Power Supply Port Type Cable Section Connecting to a Console Terminal or ModemSerial RJ-45 EIA RJ-45 Connecting to the Serial Port with Microsoft Windows Connect the OS X USB port to the router Connecting to the Console Port with Mac OSTo Disconnect the OS X USB Console from the Terminal Window Connecting to the Console Port with LinuxInstalling the Cisco Microsoft Windows 2000 USB Driver Installing the Cisco Microsoft Windows XP USB DriverInstalling the Cisco Microsoft Windows Vista USB Driver Uninstalling the Cisco Microsoft Windows USB DriverUsing the Add Remove Programs Utility Using the Setup.exe Program Uninstalling the Cisco Microsoft Windows Vista USB DriverAUX Connecting to the Auxiliary PortConnection Procedures and Precautions Connecting WAN and LAN InterfacesAuxiliary and Console Ports Ports and CablingPort or Connection Port Type, Color1 Cable Identify a Rollover Cable Pin Signal Input/OutputConsole Port Connection to a PC Signal Pin6shows the RJ-45 rolled console cable pinouts Port DTE Rollover Cable Console Port Signaling and Cabling with a DB-9 AdapterSignal RJ-45 Pin DB-9 Pin Console RJ-45 to RJ-458shows the pinout descriptions for the DB-25 connections Console Port Signaling and Cabling with a DB-25 AdapterRJ-45 to Console DB-25 Auxiliary Port Connection to a Modem Auxiliary Port Signaling and Cabling Using a DB-25 Adapter9provides the pinout description for the modem connection 10describes the alternative terminal and modem connections Alternative Terminal and Modem ConnectionsRJ-45 Cable Type Adapter CAB-HD4-232MT Cable Type Length Connector TypeCAB-HD4-232FC Port EIA-232 DCE Ft m Female DB-25Pinouts for the Synchronous/Asynchronous Cables Pin Signal Direction DescriptionRS-232 DB-25 Cable Pinouts Txce RS-232 DB-9 Cable PinoutsRXC LtstTransmit Data Pin Signal DescriptionSignal Ground RS-232 RJ-45 Cable PinoutsChecklist for Power Up Powering up the RouterThis section covers the following topics Cisco Setup Command Facility Power Up ProcedureVerifying the Power Supply Side LED Indications Performing the Initial Configuration on the RouterEnter a hostname for the router this example uses myrouter Using the Cisco Setup Command FacilityTo proceed using the setup command facility, enter yes Basic management setup configures only enough connectivitySummary of the available interfaces is displayed Following configuration command script is createdUser prompt is displayed Completing the ConfigurationUsing Cisco IOS CLI-Manual Configuration Using Cisco Configuration Professional ExpressFollowing tasks are either required or optional Configuring the Router HostnameType enable to enter privileged Exec mode Press Return to bring up the Router promptExample Configuring the Enable and Enable Secret PasswordsCommand or Action Purpose RestrictionsSecret command Optional Sets a local password to control access to variousBoot an older image of the Cisco IOS software or if you Boot older boot ROMs that do not recognize the enableConfiguring the Console Idle Privileged Exec Timeout Exec timeout Configuring Gigabit and FastEthernet Interfaces Displays the running configuration file Verify that you properly configured the idle privilegedDescription helps you remember what is attached to Configuration modeSoftware configuration guide Optional Adds a description to an interface configurationSample Output for the show ip interface brief Command Specifying a Default Route or Gateway of Last ResortConfiguring IP Routing and IP Protocols Configuring the GigabitEthernet Interface ExampleDefault Network Default RoutesGateway of Last Resort Gateway of last resort Enables IP routingEstablishes a static route Selects a network as a candidate route for computingSample Output for the show ip route Command Specifying a Default Route ExampleLine vty ? command Starts the line configuration command collection mode forVirtual terminal lines vty for remote console access Make sure that you configure all vty lines on yourWhat to Do Next Configuring the Auxiliary LineVerify that you properly configured the virtual terminal Lines for remote accessPrerequisites Verifying Network ConnectivityAuxiliary line To verify connectivity, ping the next hop router or Connected host for each configured interface toTo test the vty line password, perform this step from a Diagnoses initial network connectivityConfiguration Saving Your Router ConfigurationSaving Backup Copies of Configuration and System Image Saves the running configuration to the startupCopying from Flash Memory to a Tftp Server Example Copying the Startup Configuration to a Tftp Server ExampleNvram Verifying the Initial ConfigurationInstalling and Upgrading Internal Modules Installing and Upgrading Internal Modules Safety Warnings PSU OK Removing a Compact Flash Memory CardRemoving the Compact Flash Cover Compact Flash Memory Card Slot in Cisco CGR Installing a Compact Flash Memory CardLaser Safety Guidelines Installing SFP ModulesConnect the network cable to the SFP module Removing SFP ModulesDisconnecting SFP Latch Mechanisms Installing Single-Wide GRWICs Installing Grid Router WAN Interface CardsProper Installation of Multiple GRWICs Installing Double-Wide GRWICsRemoving the Slot Divider From the CGR 2010 Router 11 Installing the Switch Module in the CGR 2010 Router 12 The Double-Wide Grwic Installed in the CGR 2010 Router OL-31454-01
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