Cisco Systems Understanding Cisco Route Policy and iBGP Modifications on IOS XR

Models: IOS XR

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Implementing BGP on Cisco IOS XR Software

Information About Implementing BGP on Cisco IOS XR Software

Routing Policy Enforcement

External BGP (eBGP) neighbors must have an inbound and outbound policy configured. If no policy is configured, no routes are accepted from the neighbor, nor are any routes advertised to it. This added security measure ensures that routes cannot accidentally be accepted or advertised in the case of a configuration omission error.

Note This enforcement affects only eBGP neighbors (neighbors in a different autonomous system than this router). For internal BGP (iBGP) neighbors (neighbors in the same autonomous system), all routes are accepted or advertised if there is no policy.

In the following example, for an eBGP neighbor, if all routes should be accepted and advertised with no modifications, a simple pass-all policy is configured:

RP/0/RP0/CPU0:router(config)# route-policypass-all

RP/0/RP0/CPU0:router(config-rpl)# pass

RP/0/RP0/CPU0:router(config-rpl)# end-policy

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

Use the route-policy (BGP) command in the neighbor address-family configuration mode to apply the pass-all policy to a neighbor. The following example shows how to allow all IPv4 unicast routes to be received from neighbor 192.168.40.42 and advertise all IPv4 unicast routes back to it:

RP/0/RP0/CPU0:router(config)# router bgp 1

RP/0/RP0/CPU0:router(config-bgp)# neighbor 192.168.40.24

RP/0/RP0/CPU0:router(config-bgp-nbr)# remote-as 2

RP/0/RP0/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast

RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policypass-all in

RP/0/RP0/CPU0:router(config-bgp-nbr-af)# route-policypass-all out

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

Use the show bgp summary command to display eBGP neighbors that do not have both an inbound and outbound policy for every active address family. In the following example, such eBGP neighbors are indicated in the output with an exclamation (!) mark:

RP/0/RP0/CPU0:router# show bgp all all summary

Address Family: IPv4 Unicast

============================

BGP router identifier 10.0.0.1, local AS number 1

BGP generic scan interval 60 secs

BGP main routing table version 41

BGP scan interval 60 secs

BGP is operating in STANDALONE mode.

Process

RecvTblVer

bRIB/RIB

SendTblVer

 

 

 

 

Speaker

 

41

41

 

41

 

 

 

 

Neighbor

Spk

AS MsgRcvd MsgSent

TblVer

InQ OutQ

Up/Down

St/PfxRcd

10.0.101.1

0

1

919

925

41

0

0

15:15:08

10

10.0.101.2

0

2

0

0

0

0

0

00:00:00

Idle

Address Family: IPv4 Multicast

==============================

BGP router identifier 10.0.0.1, local AS number 1

BGP generic scan interval 60 secs

BGP main routing table version 1

Cisco IOS XR Routing Configuration Guide

RC-16

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Cisco Systems IOS XR manual Routing Policy Enforcement, RC-16

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.