Implementing Routing Policy on Cisco IOS XR Software

Information About Implementing Routing Policy

Table 4

Restricted BGP Operations by Attach Point

 

 

 

 

 

 

 

 

 

 

import

export

aggregation

redistribution

 

 

 

 

 

prepend as-path

eBGP only

eBGP only

n/a

n/a

 

 

 

 

 

set med igp-cost

forbidden

eBGP only

forbidden

forbidden

 

 

 

 

 

 

set weight

 

n/a

forbidden

n/a

n/a

 

 

 

 

 

 

suppress

 

forbidden

forbidden

n/a

forbidden

 

 

 

 

 

 

OSPF Policy Attach Points

This section describes each of the OSPF policy attach points and provides a summary of the OSPF attributes and operators.

Default Originate

The default originate attach point allows the user to conditionally inject the default route 0.0.0.0/0 into the OSPF link-state database, which is done by evaluating the attached policy. If any routes in the local RIB pass the policy, then the default route is inserted into the link-state database.

The following example shows how to generate a default route if any of the routes that match 10.0.0.0/8 ge 8 le 25 are present in the RIB:

route-policy ospf-originate

if rib-has-route in (10.0.0.0/8 ge 8 le 25) then pass

endif

end-policy

router ospf 1

default-information originate policy ospf-originate

.

.

.

Redistribute

The redistribute attach point within OSPF injects routes from other routing protocol sources into the OSPF link-state database, which is done by selecting the route types it wants to import from each protocol. It then sets the OSPF parameters of cost and metric type. The policy can control how the routes are injected into OSPF by using the set level command.

The following example shows how to redistribute routes from IS-IS instance instance_10 into OSPF instance 1 using the policy OSPF-redist. The policy sets the metric type to type-2 for all redistributed routes. IS-IS routes with a tag of 10 have their cost set to 100, and IS-IS routes with a tag of 20 have their OSPF cost set to 200. Any IS-IS routes not carrying a tag of either 10 or 20 are not be redistributed into the OSPF link-state database.

Cisco IOS XR Routing Configuration Guide

RC-231

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Cisco Systems IOS XR Ospf Policy Attach Points, Import Export Aggregation Redistribution Prepend as-path, Set med igp-cost

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.