Chapter 3 Configuring Additional Router Features

Configuration Limiting

Maximum Routes Redistributed into OSPF

In the following example, the maximum redistributed-prefixescommand is used to set the maximum routes redistributed into OSPF:

RP/0/RP1/CPU0:router# configure RP/0/RP1/CPU0:router(config)# router ospf 100 RP/0/RP1/CPU0:router(config-router)# maximum redistributed-prefixes 12000 RP/0/RP1/CPU0:router(config-router)# end

Uncommitted changes found, commit them? [yes]: y

RP/0/RP1/CPU0:Mar 30 16:26:52 : config[65740]: %LIBTARCFG-6-COMMIT : Configurati

on committed by user 'lab'. Use 'show configuration commit changes 1000000541' to view the changes.

RP/0/RP1/CPU0:Mar 30 16:26:52 : config[65740]: %SYS-5-CONFIG_I : Configured from console by lab

RP/0/RP1/CPU0:router#

Number of Parallel Links (max-paths)

In the following example, the maximum paths command is used to set the maximum number of parallel routes:

RP/0/RP1/CPU0:router# configure RP/0/RP1/CPU0:router(config)# router ospf 100 RP/0/RP1/CPU0:router(config-router)# maximum paths 10 RP/0/RP1/CPU0:router(config-router)# end Uncommitted changes found, commit them? [yes]: y

RP/0/RP1/CPU0:Mar 30 18:05:13 : config[65740]: %LIBTARCFG-6-COMMIT : Configurati

on committed by user 'lab'. Use 'show configuration commit changes 1000000542' to view the changes.

RP/0/RP1/CPU0:Mar 30 18:05:13 : config[65740]: %SYS-5-CONFIG_I : Configured from console by lab

RP/0/RP1/CPU0:router#

BGP Configuration Limits

The maximum number of BGP neighbors (peers) that can be configured is 1024. This number cannot be changed through configuration. Any attempt to configure additional neighbors beyond the limit fails.

To prevent neighbors (peers) from flooding BGP with advertisements, a limit is placed on the number of prefixes that can be accepted from a peer for each supported address family.

You can override the default limits for an address family with the maximum-prefixcommand. Table 3-7summarizes the maximum configuration limits for BGP.

Table 3-7

BGP Configuration Limits and Commands

 

 

 

 

 

 

 

 

 

 

Default

Absolute

 

 

 

 

Maximum

Maximum

Configuration Command

Show Current Settings Command

Feature Limit Description

Limit

Limit

(Router Configuration Mode)

(EXEC Mode)

 

 

 

 

 

Maximum number of neighbors

1024

1024

None. This limit cannot be

None

(peers).

 

 

 

changed or exceeded.

 

 

 

 

 

 

IPv4 unicast maximum prefixes

524,288

4,294,967,

maximum-prefix n

show bgp neighbor IP_address

that can be received from a

 

295

 

 

neighbor

 

 

 

 

 

 

 

 

 

 

 

Cisco IOS XR Getting Started Guide

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Cisco Systems IOS XR BGP Configuration Limits, Default Absolute Maximum Configuration Command, Feature Limit Description

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.