Cisco IOS XRConfig340 downloads

Cisco IOS XR Base Configuration

Foundational configuration for Cisco IOS XR routers (ASR 9000, NCS 5500, CRS). Covers hostname, AAA, SSH, management VRF, NTP, and syslog.

↓ example.txt

What is it?

IOS XR is Cisco's carrier-grade operating system designed for service provider core and edge routers such as the ASR 9000, NCS 5500, and CRS platforms. Unlike IOS/IOS-XE, IOS XR uses a distributed architecture where each process runs independently — this means the system can upgrade individual processes without a full reload. Configuration is transaction-based: changes are staged in a candidate configuration and only applied to the running configuration when you issue a 'commit'. This prevents partial configurations from taking effect and allows rollback if errors are detected. IOS XR also enforces user groups and task-based authorization for granular access control.

When to use

·Service provider core, edge, and peering routers (ASR 9000, NCS 5500, CRS, 8000 series)
·Any environment requiring carrier-grade high availability and in-service software upgrades (ISSU)
·Deployments needing MPLS, Segment Routing, or 400G+ scale interfaces
·Networks where transaction-based configuration management and rollback are required
·Multi-chassis and distributed routing deployments at scale

When NOT to use

·Enterprise branch or access routers — use IOS-XE (ISR 4000, Catalyst 8000) which is simpler
·Small networks where the learning curve and licensing cost of IOS XR is not justified
·Environments where engineers are exclusively IOS/IOS-XE trained and no retraining budget exists

How it compares

vs Cisco IOS-XEIOS-XE is the enterprise evolution of IOS, sharing familiar CLI. IOS XR is built from scratch for carrier scale, uses different CLI (no 'ip address', uses 'ipv4 address'), and requires 'commit' for all changes. IOS XR has better HA and scale.

vs Juniper JunosBoth use candidate/commit configuration models and run distributed architectures. Junos CLI differs (set/show/commit), but the operational model is similar. IOS XR is more common in North American service providers; Junos in EMEA and Tier-1 providers.

vs Cisco NX-OSNX-OS is a data center OS for Nexus switches, not IOS XR. NX-OS uses features ('feature ospf'), IOS XR does not. They share some CLI similarities but are architecturally different platforms with different use cases.

Prerequisites

→Physical or virtual access to the console port for initial configuration
→Basic understanding of IOS XR's commit-based configuration model (changes are staged)
→TACACS+ or RADIUS server reachable via management network for AAA
→Management network planned with a dedicated VRF for out-of-band access isolation
→NTP sources and syslog collectors identified as separate addresses, both reachable from the management VRF — a time source is not a log collector

Config Generator

Hostname *

Domain Name *

Timezone *

e.g. UTC, America/New_York, Europe/Madrid

Admin Password *

TACACS+ Key

TACACS+ Servers

NTP Servers

Syslog Servers

Where the router sends its logs. These are NOT the NTP servers — a syslog collector and a time source are different boxes, and pointing logging at the NTP servers leaves the device with no centralised logging while the config still commits cleanly.

Management VRF

Management IP *

Management Mask *

SSH/Logging Source Interface

Verification commands

show running-config

View the committed running configuration

ExpectedShows only committed changes. Pending changes are in 'show configuration' before commit.

show interfaces MgmtEth0/RP0/CPU0/0

Verify management interface is up/up with correct IP

ExpectedLine protocol is Up, correct IPv4 address shown

show ntp status

Verify NTP synchronization

ExpectedClock is synchronized, stratum should be <= 4

show aaa

Verify AAA configuration is loaded

ExpectedAuthentication and authorization methods visible

Debug commands

show configuration failed

Show why the last commit failed

WarningRun immediately after a failed commit to see validation errors

show configuration commit list

Show commit history for rollback reference

WarningUse 'rollback configuration last 1' to undo the most recent commit

Common mistakes & fixes

SymptomChanges not taking effect after editing config

CauseForgot to run 'commit' — IOS XR uses candidate configuration model

FixRun 'commit' in config mode, or 'commit confirmed 5' for a timed commit with auto-rollback

SymptomSSH not accessible after configuration

CauseSSH server not enabled or management VRF not specified

FixVerify 'ssh server v2' and 'ssh server vrf MGMT' are committed. Check management interface is up.

SymptomTACACS+ authentication failing

CauseTACACS+ key mismatch or server unreachable via management VRF

FixTest with 'test aaa group tacacs+ admin <password> new-code'. Verify route to TACACS server via MGMT VRF.

Further learning

Recommended books to go deeper on this topic.

CCNA 200-301 Official Cert Guide Library

Wendell Odom · Cisco Press · Best starting point for Cisco IOS fundamentals — CLI, interfaces, basic routing

Kindle ↗Hardcover ↗

CCNP Enterprise Core ENCOR 350-401 Official Cert Guide

Brad Edgeworth et al. · Cisco Press · For engineers ready to go deeper — routing, switching, security, automation