Cisco Systems 1900 Series manual Specifying a Default Route or Gateway of Last Resort

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Chapter 5 Configuring the Router

Performing the Initial Configuration on the Router

Specifying a Default Route or Gateway of Last Resort

This section describes how to specify a default route with IP routing enabled. For alternative methods of specifying a default route, see the Configuring a Gateway of Last Resort Using IP Commands tech note.

The Cisco IOS software uses the gateway (router) of last resort if it does not have a better route for a packet and if the destination is not a connected network. This section describes how to select a network as a default route (a candidate route for computing the gateway of last resort). The way in which routing protocols propagate the default route information varies for each protocol.

Configuring IP Routing and IP Protocols

For comprehensive configuration information about IP routing and IP routing protocols, see Cisco IOS IP Routing Protocols Configuration Guide, Release 12.4T.

•IP Routing, page 5-14

•Default Routes, page 5-14

•Default Network, page 5-14

IP Routing

You can configure integrated routing and bridging (IRB) so the router can route and bridge simultaneously. The router will act as an IP host on the network whether routing is enabled or not. To read more about IRB see the following URL on Cisco.com,

http://www.cisco.com/en/US/tech/tk389/tk815/tk855/tsd_technology_support_sub-protocol_home.html

IP routing is automatically enabled in the Cisco IOS software. When IP routing is configured, the system will use a configured or learned route to forward packets, including a configured default route.

Note This task section does not apply when IP routing is disabled. To specify a default route when IP routing is disabled, refer to the Configuring a Gateway of Last Resort Using IP Commands tech note.

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 will generate or source a default route. In the case of RIP, the router will advertise 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.

 

Cisco 1900 Series Hardware Installation

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Contents Americas Headquarters Text Part Number OL-19084-03Page OL-19084-03 Console and Auxiliary Port Considerations Chassis Airflow Diagram Configuring the Auxiliary Line Objectives AudienceOrganization ConventionsSection Title Description Convention IndicationBewaar Deze Instructies Avvertenza Importanti Istruzioni Sulla Sicurezza Warnung Wichtige SicherheitshinweiseAviso Instruções Importantes DE Segurança Guarde Estas Instrucciones GEM Disse Anvisninger Xiii Xiv Related Documentation Obtaining Documentation and Submitting a Service Request Searching within Cisco DocumentsSafety Warnings Overview of the RouterChassis Views Safety Warnings for Finland, Norway and SwedenSYS ACT PoE12 Cisco Antenna mounts1 LEDs2 SYS ACTWlan 4 or 5 GHzHardware Features Overview of the Router Hardware FeaturesProduct Serial Number Location CleiBuilt-In Interfaces Cisco Product Identification ToolProduct ID PID Compliance label CleiRemovable, Interchangeable, and Optional Modules Interface DescriptionUSB Such as security tokens and flash memoryMemory External Modules In chassis slots Internal ModulesSeries 1905 1921 DramColor Description Location LED IndicatorsSYS ISM/WLAN Wireless LAN Connectivity Chassis VentilationReal-Time Clock Chassis SecurityBaud Reset Button Interface NumberingSlot Number Slot Type Slot Numbering Range Onboard Ports 10/100/1000 EthernetDescription Specification Physical SpecificationsPower Description Specification PortsTransportation and Storage Environment AcousticTIA/EIA/IS-968 CNS Regulatory Compliance ITU-T G.823, G.824Safety Recommendations General GuidelinesSafety with Electricity General Site Requirements Preventing Electrostatic Discharge DamageSite Configuration Power Supply ConsiderationsSite Environment Installation Checklist Wireless LAN ConsiderationsInspecting the Router Task Verified byInstallation Checklist for Site Router Name Site LogTask Verified by Date Router quick start guide receivedCisco 1900 Series Hardware Installation OL-19084-02 OL-19084-02 About Console and Auxiliary Ports Console and Auxiliary Port ConsiderationsConsole Port Connections USB Serial Console EIA/TIA-232 PortUSB Console OS Compatibility Preparing to Connect to a Network Auxiliary Port ConnectionsEthernet Connections Serial ConnectionsConfiguring Serial Connections Signaling Standards SupportedAbout Serial Connections Serial DTE or DCE DevicesTransmission Speeds and Distance Limitations Asynchronous/Synchronous Serial Module Baud RatesDistance for EIA/TIA-232 EIA-530 Distance for USB Rate bps Feet MetersIsdn BRI Connections CSU/DSU ConnectionsLow-Capacitance Cable For more information on BRI WICs, refer to Cisco.comInternal services module ISM About ModulesInternal Modules Router’s internal components include the followingPlug-In Modules Setting Up the Chassis Chassis Airflow DiagramChassis Grounding Setting the Chassis on a DesktopWall-Mounting the Chassis 253711 Procedure Wall-Mounting Features on the Cisco 1941 RouterRack-Mounting the Chassis Attaching Rack-Mount Brackets to Cisco 1900 Series Routers253712 Installing the Chassis Ground Connection 9shows how to attach the brackets to the rack11 Chassis Ground Connection on the Cisco 1941 Router Connecting WAN and LAN Cables Safety MessagesOL-19084-02 Ports and Cabling Port Type, Color Connected to CableConnection Procedures and Precautions Connecting to a Console Terminal or ModemConnecting to the Console Port with Microsoft Windows 12 Connecting the Console Cable to the Router Connecting to the Console Port with Mac OS Connecting to the Console Port with LinuxOpen the Linux Terminal window Connect the Linux USB port to the routerInstalling the Cisco Microsoft Windows 2000 USB Driver Installing the Cisco Microsoft Windows XP USB DriverBefore You Begin Procedure Uninstalling the Cisco USB Driver Installing the Cisco Microsoft Windows Vista USB DriverUsing the Add Remove Programs Utility Before You BeginUninstalling the Cisco Microsoft Windows Vista USB Driver Using the Setup.exe ProgramConnecting to the Auxiliary Port 13 Connecting a Modem to the RouterConnecting Power Connecting to AC PowerConnecting to DC Power DC Wiring Requirements for Cisco 1900 Series RoutersWire Size Wire Terminal Lug Protection DC InputCisco 1900 Series Router Wiring Procedure for DC Input 14 DC Power Wire Connection 15 Installing the Plastic Safety Cover OL-19084-02 Powering up the Router Checklist Before Powering Up the Cisco RouterPowering Up the Cisco Router Related InformationPerforming the Initial Configuration on the Router Using the Cisco Setup Command Facility5-6 to configure the router Verifying the Front Panel LED IndicationsEnter a hostname for the router To proceed using the setup command facility, enter yesSystem displays a summary of the available interfaces System creates the following configuration command script System displays the user promptUsing Cisco Configuration Professional Express Using the Cisco CLI-Manual ConfigurationInitial CLI Configuration When the system message appears on the router, enter noType enable to enter privileged Exec mode Press Return to bring up the Router promptConfiguring the Router Hostname Command or Action PurposeVerify that the router prompt displays your new hostname ExampleConfiguring the Enable and Enable Secret Passwords Optional Returns to privileged Exec modeConfiguring the Console Idle Privileged Exec Timeout Command collection mode That the privileged Exec command interpreter waits untilExample shows how to specify no timeout. Setting Exec-timeout value to 0 will cause the router toFor IP Configuring Gigabit Ethernet InterfacesLearn which type of Ethernet interface is on your Configuring the GigabitEthernet Interface Sample Output for the show ip interface brief CommandSpecifying a Default Route or Gateway of Last Resort Configuring IP Routing and IP ProtocolsRouterconfig# ip routing Gateway of Last ResortSpecifying a Default Route Example Sample Output for the show ip route CommandStarts the line configuration command collection mode for Virtual terminal lines vty for remote console accessMake sure that you configure all vty lines on your Line vty ? commandConfiguring the Auxiliary Line ExampleVerifying Network Connectivity Auxiliary lineConnected host for each configured interface If you want to test the vty line password, perform thisDiagnoses initial network connectivity To verify connectivity, ping the next hop router orSaving Your Router Configuration Saving Backup Copies of Configuration and System ImageSaves the running configuration to the startup ConfigurationCopying the Startup Configuration to a Tftp Server Example Copying from Flash Memory to a Tftp Server ExampleVerifying the Initial Configuration NvramOL-19084-02 Activating a New Software Package or Feature Getting Software Licenses for the RouterRMA License Transfer 1shows the steps for software activationAdditional Information OL-19084-02
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