user manual
Table Of Contents
- Cisco IOS XR Routing Configuration Guide
- Contents
- Preface
- Document Revision History
- Obtaining Documentation
- Documentation Feedback
- Cisco Product Security Overview
- Obtaining Technical Assistance
- Obtaining Additional Publications and Information
- Implementing BGP on Cisco IOS XR Software
- Contents
- Prerequisites for Implementing BGP on CiscoIOSXR Software
- Information About Implementing BGP on CiscoIOSXR Software
- BGP Functional Overview
- BGP Router Identifier
- BGP Default Limits
- BGP Validation of Local Next-Hop Addresses
- BGP Configuration
- No Default Address Family
- Routing Policy Enforcement
- Table Policy
- Update Groups
- BGP Best Path Algorithm
- Multiprotocol BGP
- Route Dampening
- BGP Routing Domain Confederation
- BGP Route Reflectors
- Default Address Family for show Commands
- How to Implement BGP on CiscoIOSXR Software
- Enabling BGP Routing
- Configuring a Routing Domain Confederation for BGP
- Resetting eBGP Session Immediately Upon Link Failure
- Logging Neighbor Changes
- Adjusting BGP Timers
- Changing the BGP Default Local Preference Value
- Configuring the MED Metric for BGP
- Configuring BGP Weights
- Tuning the BGP Best Path Calculation
- Indicating BGP Backdoor Routes
- Configuring Aggregate Addresses
- Redistributing iBGP Routes into IGP
- Redistributing Prefixes into Multiprotocol BGP
- Configuring BGP Route Dampening
- Applying Policy When Updating the Routing Table
- Setting BGP Administrative Distance
- Configuring a BGP Neighbor Group
- Configuring a BGP Neighbor
- Configuring a Route Reflector for BGP
- Configuring BGP Route Filtering by Route Policy
- Disabling Next Hop Processing on BGP Updates
- Configuring BGP Community and Extended-Community Filtering
- Configuring Software to Store Updates from a Neighbor
- Disabling a BGP Neighbor
- Resetting Neighbors Using BGP Dynamic Inbound Soft Reset
- Resetting Neighbors Using BGP Outbound Soft Reset
- Resetting Neighbors Using BGP Hard Reset
- Clearing Caches, Tables and Databases
- Displaying System and Network Statistics
- Monitoring BGP Update Groups
- Configuration Examples for Implementing BGP on CiscoIOSXR Software
- Where to Go Next
- Additional References
- Implementing IS-IS on Cisco IOS XR Software
- Contents
- Prerequisites for Implementing IS-IS on CiscoIOSXR Software
- Restrictions for Implementing IS-IS on CiscoIOSXR Software
- Information About Implementing IS-IS on CiscoIOSXR Software
- IS-IS Functional Overview
- Key Features Supported in the CiscoIOSXR IS-IS Implementation
- IS-IS Configuration Grouping
- IS-IS Interfaces
- Multitopology Configuration
- IPv6 Routing and Configuring IPv6 Addressing
- Limit LSP Flooding
- Maximum LSP Lifetime and Refresh Interval
- Overload Bit Configuration During Multitopology Operation
- Single-Topology IPv6 Support
- Multitopology IPv6 Support
- Nonstop Forwarding
- Multi-Instance IS-IS
- Multiprotocol Label Switching Traffic Engineering
- Overload Bit on Router
- Default Routes
- Attached Bit on an IS-IS Instance
- Multicast-Intact Feature
- How to Implement IS-IS on CiscoIOSXR Software
- Enabling IS-IS and Configuring Level 1 or Level 2 Routing
- Configuring Single Topology for IS-IS
- Configuring Multitopology for IS-IS
- Controlling LSP Flooding for IS-IS
- Configuring Nonstop Forwarding for IS-IS
- Configuring Authentication for IS-IS
- Configuring MPLS Traffic Engineering for IS-IS
- Tuning Adjacencies for IS-IS on Point-to-Point Interfaces
- Setting SPF Interval for a Single-Topology IPv4 and IPv6 Configuration
- Enabling Multicast-Intact for IS-IS
- Customizing Routes for IS-IS
- Configuration Examples for Implementing IS-IS on CiscoIOSXR Software
- Where to Go Next
- Additional References
- Implementing OSPF on Cisco IOS XR Software
- Contents
- Prerequisites for Implementing OSPF on CiscoIOSXR Software
- Information About Implementing OSPF on CiscoIOSXR Software
- OSPF Functional Overview
- Key Features Supported in the CiscoIOSXR OSPF Implementation
- Comparison of CiscoIOSXR OSPFv3 and OSPFv2
- Importing Addresses into OSPFv3
- OSPF Hierarchical CLI and CLI Inheritance
- OSPF Routing Components
- OSPF Process and Router ID
- Supported OSPF Network Types
- Route Authentication Methods for OSPF Version 2
- Neighbors and Adjacency for OSPF
- Designated Router (DR) for OSPF
- Default Route for OSPF
- Link-State Advertisement Types for OSPF Version 2
- Link-State Advertisement Types for OSPFv3
- Virtual Link and Transit Area for OSPF
- Route Redistribution for OSPF
- OSPF Shortest Path First Throttling
- Nonstop Forwarding for OSPF Version 2
- Load Balancing in OSPF Version 2 and OSPFv3
- Graceful Restart for OSPFv3
- Multicast-Intact Feature
- How to Implement OSPF on CiscoIOSXR Software
- Enabling OSPF
- Configuring Stub and Not-so-Stubby Area Types
- Configuring Neighbors for Nonbroadcast Networks
- Configuring Authentication at Different Hierarchical Levels for OSPF Version 2
- Controlling the Frequency that the Same LSA Is Originated or Accepted for OSPF
- Creating a Virtual Link with MD5 Authentication to Area 0 for OSPF
- Summarizing Subnetwork LSAs on an OSPF ABR
- Redistributing Routes from One IGP into OSPF
- Configuring OSPF Shortest Path First Throttling
- Configuring Nonstop Forwarding for OSPF Version 2
- Configuring OSPF Version 2 for MPLS Traffic Engineering
- Verifying OSPF Configuration and Operation
- Configuring OSPFv3 Graceful Restart
- Enabling Multicast-Intact for OSPFv2
- Configuration Examples for Implementing OSPF on CiscoIOSXR Software
- CiscoIOSXR for OSPF Version 2 Configuration: Example
- CLI Inheritance and Precedence for OSPF Version 2: Example
- MPLS TE for OSPF Version 2: Example
- ABR with Summarization for OSPFv3: Example
- ABR Stub Area for OSPFv3: Example
- ABR Totally Stub Area for OSPFv3: Example
- Route Redistribution for OSPFv3: Example
- Virtual Link Configured Through Area 1 for OSPFv3: Example
- Virtual Link Configured with MD5 Authentication for OSPF Version 2: Example
- Where to Go Next
- Additional References
- Implementing and Monitoring RIB on CiscoIOSXR Software
- Contents
- Prerequisites for Implementing RIB on CiscoIOSXR Software
- Information About RIB Configuration
- How to Deploy and Monitor RIB
- Configuration Examples for RIB Monitoring
- Output of show route Command: Example
- Output of show route backup Command: Example
- Output of show route best-local Command: Example
- Output of show route connected Command: Example
- Output of show route local Command: Example
- Output of show route longer-prefixes Command: Example
- Output of show route next-hop Command: Example
- Where to Go Next
- Additional References
- Implementing Routing Policy on Cisco IOS XR Software
- Implementing Static Routes on Cisco IOS XR Software
- Index
Implementing Static Routes on Cisco IOS XR Software
Information About Implementing Static Routes on Cisco IOS XR Software
RC-249
Cisco IOS XR Routing Configuration Guide
routes. For example, you could have routes installed by the Open Shortest Path First (OSPF) protocol
with an administrative distance of 120. To have a static route that would be overridden by an OSPF
dynamic route, specify an administrative distance greater than 120.
Directly Connected Routes
The routing table considers the static routes that point to an interface as “directly connected.” Directly
connected networks are advertised by IGP routing protocols if a corresponding interface command is
contained under the router configuration stanza of that protocol.
In directly attached static routes, only the output interface is specified. The destination is assumed to be
directly attached to this interface, so the packet destination is used as the next hop address. The following
example shows how to specify that all destinations with address prefix 2001:0DB8::/32 are directly
reachable through interface GigabitEthernet 0/5/0/0:
RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 gigabitethernet 0/5/0/0
Directly attached static routes are candidates for insertion in the routing table only if they refer to a valid
interface; that is, an interface that is both up and has IPv4 or IPv6 enabled on it.
Recursive Static Routes
In a recursive static route, only the next hop is specified. The output interface is derived from the next
hop. The following example shows how to specify that all destinations with address prefix
2001:0DB8::/32 are reachable through the host with address 2001:0DB8:3000::1:
RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1
A recursive static route is valid (that is, it is a candidate for insertion in the routing table) only when the
specified next hop resolves, either directly or indirectly, to a valid output interface, provided the route
does not self-recurse, and the recursion depth does not exceed the maximum IPv6 forwarding recursion
depth.
A route self-recurses if it is itself used to resolve its own next hop. If a static route becomes
self-recursive, RIB sends a notification to static routes to withdraw the recursive route.
The following example shows how to define a recursive IPv6 static route:
RP/0/RP0/CPU0:router(config)# route ipv6 unicast 2001:0DB8::/32 2001:0DB8:3000::1
This static route is not inserted into the IPv6 routing table because it is self-recursive. The next hop of
the static route, 2001:0DB8:3000:1, resolves through the BGP route 2001:0DB8:3000:0/16, which is
itself a recursive route (that is, it only specifies a next hop). The next hop of the BGP route,
2001:0DB8::0104, resolves through the static route. Therefore, the static route would be used to resolve
its own next hop.
It is not normally useful to manually configure a self-recursive static route, although it is not prohibited.
However, a recursive static route that has been inserted in the routing table may become self-recursive
as a result of some transient change in the network learned through a dynamic routing protocol. If this
occurs, the fact that the static route has become self-recursive will be detected and it will be removed
from the routing table, although not from the configuration. A subsequent network change may cause
the static route to no longer be self-recursive, in which case it will be re-inserted in the routing table.