Cisco Systems IOS XR manual Changing the BGP Default Local Preference Value, RC-35

Page 51

Implementing BGP on Cisco IOS XR Software

How to Implement BGP on Cisco IOS XR Software

 

Command or Action

Purpose

Step 4

 

 

neighbor ip-address

Places the router in neighbor configuration mode for BGP

 

 

routing and configures the neighbor IP address

 

Example:

172.168.40.24 as a BGP peer.

 

 

 

RP/0/RP0/CPU0:router(config-bgp)# neighbor

 

 

172.168.40.24

 

Step 5

 

 

timers keepalive hold-time

(Optional) Sets the keepalive timer to 60 seconds and the

 

 

hold-time timer to 220 seconds for BGP neighbor

 

Example:

172.168.40.24.

 

 

 

RP/0/RP0/CPU0:router(config-bgp-nbr)# timers 60

 

 

220

 

Step 6

 

 

end

Saves configuration changes.

 

or

When you issue the end command, the system prompts

 

 

 

commit

you to commit changes:

 

 

Uncommitted changes found, commit them before

 

Example:

exiting(yes/no/cancel)?

 

RP/0/RP0/CPU0:router(config-bgp-nbr)# end

[cancel]:

 

 

 

or

Entering yes saves configuration changes to the

 

RP/0/RP0/CPU0:router(config-bgp-nbr)# commit

 

running configuration file, exits the configuration

 

 

session, and returns the router to EXEC mode.

 

 

Entering no exits the configuration session and

 

 

returns the router to EXEC mode without

 

 

committing the configuration changes.

 

 

Entering cancel leaves the router in the current

 

 

configuration session without exiting or

 

 

committing the configuration changes.

 

 

Use the commit command to save the configuration

 

 

changes to the running configuration file and remain

 

 

within the configuration session.

 

 

 

Changing the BGP Default Local Preference Value

Perform this task to set the default local preference value for BGP paths.

SUMMARY STEPS

1.configure

2.router bgp autonomous-system-number

3.bgp default local-preference value

4.end or commit

Cisco IOS XR Routing Configuration Guide

RC-35

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Contents Corporate Headquarters Cisco IOS XR Routing Configuration GuideCisco IOS XR Routing Configuration Guide N T E N T S RC-iv Enabling BGP RoutingStandards RC-80 MIBs MIBs RC-vii Cisco IOS XR for Ospf Version 2 Configuration ExampleRC-viii Output of show route backup Command Example RC-201RC-ix Recursive Static Routes RC-249RC-x Revision Date Change Summary Document Revision HistoryOrdering Documentation Obtaining DocumentationCisco.com Product Documentation DVDXiii Reporting Security Problems in Cisco ProductsDocumentation Feedback Cisco Product Security OverviewObtaining Technical Assistance Cisco Technical Support & Documentation WebsiteXiv Submitting a Service Request Definitions of Service Request SeverityObtaining Additional Publications and Information Xvi Implementing BGP on Cisco IOS XR Software ContentsRC-2 BGP Functional OverviewBGP Default Limits BGP Router IdentifierRC-3 RC-4 BGP ConfigurationConfiguration Modes BGP Validation of Local Next-Hop AddressesNeighbor Address Family Configuration Mode Router Configuration ModeGlobal Address Family Configuration Mode Neighbor Configuration ModeRC-6 Configuration TemplatesRC-7 Template Inheritance RulesRC-8 RC-9 RC-10 Template Inheritance Show bgp neighborsRC-11 RC-12 Show bgp af-groupRC-13 Show bgp session-groupRC-14 Show bgp neighbor-groupRC-15 No Default Address FamilyRC-16 Routing Policy EnforcementRC-17 Table Policy Update GroupsBGP Update Generation and Update Groups BGP Update GroupRC-19 Comparing Pairs of PathsRC-20 Order of ComparisonsMultiprotocol BGP Best Path Change SuppressionRC-21 Incongruent Unicast and Multicast Routes RC-22RC-23 Route DampeningRC-24 BGP Routing Domain ConfederationBGP Route Reflectors Minimizing FlappingThree Fully Meshed iBGP Speakers RC-25More Complex BGP Route Reflector Model RC-26How to Implement BGP on Cisco IOS XR Software Default Address Family for show CommandsRC-27 Enabling BGP Routing PrerequisitesRC-28 RC-29 Command or Action PurposeRestrictions ExampleRC-30 As a BGP peerRC-31 Configuring a Routing Domain Confederation for BGPRC-32 RC-33 Resetting eBGP Session Immediately Upon Link FailureAdjusting BGP Timers Logging Neighbor ChangesRC-34 RC-35 Changing the BGP Default Local Preference ValueRC-36 Configuring the MED Metric for BGPRC-37 RC-38 Configuring BGP WeightsRC-39 Tuning the BGP Best Path CalculationRC-40 Path the least desirable pathRC-41 Indicating BGP Backdoor RoutesRC-42 RC-43 Configuring Aggregate AddressesRC-44 Redistributing iBGP Routes into IGPRC-45 RC-46 Redistributing Prefixes into Multiprotocol BGPRC-47 To be redistributed into BGPRC-48 Configuring BGP Route DampeningRC-49 RC-50 RC-51 RC-52 Applying Policy When Updating the Routing TableRC-53 Setting BGP Administrative DistanceRC-54 RC-55 Configuring a BGP Neighbor GroupRC-56 RC-57 Bytes for the BGP bufferRC-58 Configuring a BGP NeighborRC-59 RC-60 Configuring a Route Reflector for BGPRC-61 RC-62 Configuring BGP Route Filtering by Route PolicyRC-63 RC-64 Disabling Next Hop Processing on BGP UpdatesRC-65 Configuring BGP Community and Extended-Community FilteringRC-66 RC-67 Configuring Software to Store Updates from a NeighborRC-68 RC-69 Disabling a BGP NeighborRC-70 Resetting Neighbors Using BGP Dynamic Inbound Soft Reset Resetting Neighbors Using BGP Outbound Soft ResetRC-71 RC-72 Resetting Neighbors Using BGP Hard ResetClearing Caches, Tables and Databases Displaying System and Network StatisticsRC-73 RC-74 Performance-statistics keyword displaysRC-75 Monitoring BGP Update GroupsRC-76 Enabling BGP ExampleRC-77 Displaying BGP Update Groups ExampleBGP Neighbor Configuration Example BGP Confederation ExampleRC-78 Where to Go Next BGP Route Reflector ExampleRC-79 MIBs Additional ReferencesRelated Documents StandardsRC-81 Technical AssistanceRFCs Description LinkRC-82 RC-83 Implementing IS-IS on Cisco IOS XR SoftwareRC-84 IS-IS Configuration Grouping IS-IS Functional OverviewRC-85 Limit LSP Flooding Multitopology ConfigurationIPv6 Routing and Configuring IPv6 Addressing IS-IS InterfacesSingle-Topology IPv6 Support Overload Bit Configuration During Multitopology OperationMesh Group Configuration Maximum LSP Lifetime and Refresh IntervalMultitopology IPv6 Support Nonstop ForwardingRC-88 RC-89 Multiprotocol Label Switching Traffic EngineeringMulti-Instance IS-IS Overload Bit on RouterRC-90 Default RoutesMulticast-Intact Feature Attached Bit on an IS-IS InstanceHow to Implement IS-IS on Cisco IOS XR Software Enabling IS-IS and Configuring Level 1 or Level 2 RoutingRC-91 RC-92 RC-93 Configuring Single Topology for IS-ISRC-94 Ipv4 address address mask orRC-95 Specifying the ipv6 address ipv6-prefix /prefix-lengthRC-96 See the Single-Topology IPv6 Support section onRC-97 Level-2-only adjacenciesRC-98 Configuring Multitopology for IS-ISRC-99 RC-100 RC-101 RC-102 Controlling LSP Flooding for IS-ISRC-103 Max-lsp-lifetime commandRC-104 LSP was not received and subsequently resendsRC-105 RC-106 Configuring Nonstop Forwarding for IS-ISRC-107 RC-108 Configuring Authentication for IS-ISRC-109 Configuring Mpls Traffic Engineering for IS-IS PrerequisiteRC-110 RC-111 RC-112 RC-113 Tuning Adjacencies for IS-IS on Point-to-Point InterfacesRC-114 To all interfacesRC-115 RC-116 Command or Action PurposeRC-117 Enabling Multicast-Intact for IS-IS Summary StepsRC-118 RC-119 Customizing Routes for IS-ISRC-120 RC-121 Instance 2 routes into its Level 1 areaRC-122 Configuring Single-Topology IS-IS for IPv6 ExampleRC-123 Configuring Multitopology IS-IS for IPv6 ExampleRC-124 RC-125 RC-126 RC-127 Implementing Ospf on Cisco IOS XR SoftwareRC-128 Information About Implementing Ospf on Cisco IOS XR SoftwareRC-129 Ospf Functional OverviewRC-130 RC-131 Comparison of Cisco IOS XR OSPFv3 and OSPFv2Importing Addresses into OSPFv3 Ospf Hierarchical CLI and CLI InheritanceOspf Routing Components Autonomous SystemsRC-132 Not-so-Stubby Area Nssa AreasBackbone Area Stub AreaAutonomous System Boundary Routers Asbr Ospf Process and Router IDRouters Area Border Routers ABRSupported Ospf Network Types Route Authentication Methods for Ospf VersionPlain Text Authentication MD5 AuthenticationKey Rollover Authentication StrategiesNeighbors and Adjacency for Ospf Designated Router DR for OspfRC-137 Default Route for OspfLink-State Advertisement Types for Ospf Version Link-State Advertisement Types for OSPFv3RC-138 Virtual Link and Transit Area for OspfRoute Redistribution for Ospf Ospf Shortest Path First ThrottlingRC-139 RC-140 Nonstop Forwarding for Ospf VersionLoad Balancing in Ospf Version 2 and OSPFv3 Graceful Restart for OSPFv3RC-141 Helper Mode Modes of Graceful Restart OperationRC-142 RC-143 Graceful Restart Requirements and RestrictionsRC-144 How to Implement Ospf on Cisco IOS XR SoftwareRC-145 Enabling OspfRC-146 RC-147 Configuring Stub and Not-so-Stubby Area TypesRC-148 RC-149 Default-information-originate, and no-summaryRC-150 Configuring Neighbors for Nonbroadcast NetworksRC-151 RC-152 RC-153 RC-154 RC-155 RC-156 Message-digest-key key-idmd5 key clear key encrypted keyRC-157 RC-158 OspfRC-159 Default is 1 secondRC-160 RC-161 RC-162 Section on page RC-138RC-163 Summarizing Subnetwork LSAs on an Ospf ABR ExamplesRC-164 RC-165 RC-166 Redistributing Routes from One IGP into OspfRC-167 RC-168 Another routing domainRC-169 RC-170 Configuring Ospf Shortest Path First ThrottlingRC-171 RC-172 RC-173 Configuring Nonstop Forwarding for Ospf VersionRC-174 RC-175 Configuring Ospf Version 2 for Mpls Traffic EngineeringRC-176 Mpls traffic-eng area area-idRC-177 RP/0/RP0/CPU0router# show route ospf 1 RC-178RC-179 Sample Output for the show ospf mpls traffic-eng CommandRC-180 Verifying Ospf Configuration and OperationRC-181 Configuring OSPFv3 Graceful RestartConfiguring the Maximum Lifetime of a Graceful Restart Enabling Graceful RestartRC-182 RC-183 Configuring the Minimum Time Required Between RestartsRC-184 Configuring the Helper Level of the RouterDisplaying the State of the Graceful Restart Feature Displaying Information About Graceful RestartRC-185 RC-186 Enabling Multicast-Intact for OSPFv2RC-187 Cisco IOS XR for Ospf Version 2 Configuration Example Cisco IOS XR Software ConfigurationRC-188 RC-189 CLI Inheritance and Precedence for Ospf Version 2 ExampleRC-190 Mpls TE for Ospf Version 2 ExampleABR with Summarization for OSPFv3 Example ABR Stub Area for OSPFv3 ExampleRC-191 Virtual Link Configured Through Area 1 for OSPFv3 ExampleABR Totally Stub Area for OSPFv3 Example Route Redistribution for OSPFv3 ExampleRC-192 RC-193 MIBsRC-194 RC-195 Implementing and Monitoring RIB on Cisco IOS XR SoftwareRC-196 Information About RIB ConfigurationOverview of RIB RIB Data Structures in BGP and Other ProtocolsRC-197 RIB Administrative DistanceProtocol Administrative Distance Default RIB Support for IPv4 and IPv6RC-198 How to Deploy and Monitor RIBVerifying RIB Configuration Using the Routing Table Verifying Networking and Routing ProblemsRC-199 Configuration Examples for RIB Monitoring Output of show route Command ExampleRC-200 Output of show route local Command Example Output of show route backup Command ExampleOutput of show route best-local Command Example Output of show route connected Command ExampleOutput of show route longer-prefixes Command Example Output of show route next-hop Command ExampleRC-202 RC-203 Cisco IOS XR Multicast Command Reference, ReleaseRC-204 RC-205 Implementing Routing Policy on Cisco IOS XR SoftwareRouting Policy Language Overview Prerequisites for Implementing Routing PolicyInformation About Implementing Routing Policy Routing Policy LanguageRC-207 Routing Policy Language StructureNames SetsRC-208 As-path-setNamed Set Form Inline Set FormRC-209 Community-setExtcommunity-set Named FormPrefix-set Inline FormRC-210 RC-211 Routing Policy Language ComponentsRouting Policy Language Usage Pass policyRC-212 Ignore routes with specific AS numbers in the pathSet community based on MED Set local preference based on communityRC-213 Routing Policy Configuration BasicsPolicy Definitions Persistent RemarksRC-214 ParameterizationSemantics of Policy Application Boolean Operator PrecedenceRC-215 When Attributes Are Modified Multiple Modifications of the Same AttributeRC-216 Default Drop Disposition Control FlowRC-217 RC-218 Policy VerificationRange Checking Incomplete Policy and Set ReferencesVerification of Attribute Comparisons and Actions Policy StatementsRemark Attached Policy ModificationRC-220 DispositionRC-221 ActionRC-222 Boolean ConditionsAttach Points ApplyRC-223 BGP Policy Attach Points AggregationRC-224 Default Originate DampeningRC-225 Neighbor Export Neighbor ImportRC-226 Network RedistributeRC-227 RC-228 Show bgpTable Policy BGP Attributes and OperatorsRC-229 RC-230 Attribute Match SetSuppress Ospf Policy Attach PointsImport Export Aggregation Redistribution Prepend as-path Set med igp-costOSPFv3 Policy Attach Points Ospf Attributes and OperatorsRC-232 RC-233 OSPFv3 Attributes and OperatorsIS-IS Policy Attach Points IS-IS Attributes and OperatorsRC-234 RC-235 Editing Routing Policy Configuration ElementsAttached Policy Modification Nonattached Policy ModificationRC-236 Editing Routing Policy Configuration Elements Using the CLIHow to Implement Routing Policy Defining a Route PolicyRC-237 RC-238 Attaching a Routing Policy to a BGP NeighborRC-239 Enters address family configuration modeRC-240 Modifying a Routing Policy Using the Microemacs EditorRC-241 Routing Policy Definition ExampleRC-242 Simple Inbound Policy ExampleRC-243 Modular Inbound Policy ExampleRC-244 Routing Policy Language Commands on Cisco IOS XR SoftwareRC-245 RC-246 RC-247 SoftwareDefault Administrative Distance Static Route Functional OverviewRC-248 Directly Connected Routes Recursive Static RoutesRC-249 RC-250 Configuring a Static RouteFully Specified Static Routes Floating Static RoutesRC-251 Configuring a Floating Static RouteRC-252 RC-253 Changing the Maximum Number of Allowable Static RoutesRC-254 Configuring a Floating Static Route Example Configuration ExamplesConfiguring Traffic Discard Example Configuring a Fixed Default Route ExampleRC-256 RC-257 D ERC-258 RC-259 RC-260 RC-261 IS-IS RC-90RC-262 MD5RC-263 RFC 2328, Ospf VersionRC-264 RC-265 RC-266
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IOS XR specifications

Cisco Systems IOS XR is an advanced operating system designed specifically for high-performance routers and service provider networks. It serves as the backbone for many of Cisco's high-end routing platforms, enabling service providers to manage their networks with increased efficiency, flexibility, and scalability.

One of the main features of IOS XR is its modular architecture. This allows for the independent operation of various components within the OS, facilitating the deployment of new features and updates without affecting the overall stability of the system. This modularity ensures that service providers can implement rapid changes and enhancements while maintaining service continuity.

Another characteristic of IOS XR is its support for 64-bit architecture, which provides enhanced performance and the ability to manage larger amounts of data. This is particularly beneficial for service providers that deal with high traffic volumes and require robust data processing capabilities. The utilization of 64-bit technology also enables the operating system to utilize memory more efficiently, allowing for greater scalability.

IOS XR incorporates advanced technologies such as Distributed System Architecture (DSA) and Multiple Routing Instances (Merging Routes). DSA allows for the distribution of routing processes across multiple hardware resources, maximizing performance and redundancy. Multiple Routing Instances enable operators to create separate logical routing tables for different services, improving isolation and efficiency in managing network traffic.

The operating system also focuses heavily on security, featuring extensive encryption methods and access controls to safeguard network resources. IOS XR supports various authentication protocols, ensuring secure access to routers and switches. In addition, the OS includes comprehensive logging and monitoring capabilities, allowing network administrators to track activities and respond quickly to potential threats.

Another critical aspect of IOS XR is its adherence to the principles of service-oriented architecture (SOA). This approach permits the development of applications and services that can operate independently, fostering innovation and enabling service providers to tailor their offerings based on customer demands.

Ultimately, Cisco IOS XR is a powerful, reliable operating system that meets the complex needs of modern telecommunications networks. With its focus on modularity, performance, security, and scalability, it enables service providers to deliver high-quality, resilient services to their customers while efficiently managing network resources. As the industry continues to evolve, IOS XR remains a vital tool for those aiming to stay competitive in the ever-changing landscape of networking.