Chapter 3 Configuring Additional Router Features

Configuration Limiting

A cease-notification message is sent to the neighbor and the peering with the neighbor is terminated when the number of prefixes received from the peer for a given address family exceeds the maximum limit (either set by default or configured by the user) for that address family.

However, if the warning-onlykeyword (for the maximum-prefixcommand) is configured, the Cisco IOS XR software sends only a log message, but continues peering with the sender. If the peer is terminated, the peer stays down until the clear bgp command is issued.

The same set of actions (sending cease notification followed by the termination of the peering) is taken for a neighbor with which peering has already been established if you decide to configure a maximum that is less than the number of prefixes that have already been received from the neighbor.

Examples

The following example shows how to set the maximum number of IPv4 unicast prefixes allowed from the neighbor at 10.1.1.1 to 100,000:

RP/0/RP1/CPU0:router# configure RP/0/RP1/CPU0:router(config)# router bgp 100 RP/0/RP1/CPU0:router(config-bgp)# neighbor 10.1.1.1 RP/0/RP1/CPU0:router(config-bgp-nbr)# remote-as 1 RP/0/RP1/CPU0:router(config-bgp-nbr)# address-family ipv4 unicast RP/0/RP1/CPU0:router(config-bgp-nbr-af)# maximum-prefix 100000 RP/0/RP1/CPU0:router(config-bgp-nbr-af)# commit

RP/0/RP1/CPU0:Mar 30 19:13:16 : config[65740]: %LIBTARCFG-6-COMMIT : Configurati

on committed by user 'lab'. Use 'show configuration commit changes 1000000544' to view the c

hanges.

RP/0/RP1/CPU0:Mar 30 19:13:17 : config[65740]: %SYS-5-CONFIG_I : Configured from console by lab

RP/0/RP1/CPU0:router(config-bgp-nbr-af)#

Routing Policy Language Line and Policy Limits

Two limits for Routing Policy Language (RPL) configurations exist:

1.Lines of configuration: The number of lines entered by the user, including the beginning and ending statements (that is “route-policy”). The lines of configuration for sets are also included.

2.Number of RPL policies: The number of policies that can be configured on the router. Policies are

counted only once: Multiple use of the same policy counts as a single policy toward the limit 1.

The limits for RPL lines and policies are summarized in Table 3-8. You can change the default values up to the absolute maximum, but you cannot change the value to a number less than the number of items that are currently configured.

Table 3-8

Maximum Lines of RPL: Configuration Limits and Commands

 

 

 

 

 

 

 

 

 

Default

Absolute

 

Show Current Settings

 

 

Maximum

Maximum

Configuration Command

Command

Limit Description

Limit

Limit

(Global Configuration Mode)

(EXEC Mode)

 

 

 

 

 

Maximum number of RPL lines

65,536

131,072

rpl maximum lines n

show rpl maximum lines

 

 

 

 

 

Maximum number of RPL policies

3500

5000

rpl maximum policies n

show rpl max policies

 

 

 

 

 

 

Cisco IOS XR Getting Started Guide

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Cisco Systems IOS XR manual Routing Policy Language Line and Policy Limits

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.