Cisco IOS XR

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Line card running IOS XR.

IOS XR is a train of Cisco Systems' widely deployed Internetworking Operating System (IOS), used on their high-end Network Converging System (NCS), carrier-grade routers such as the CRS series, 12000 series, and ASR9000 series.

Architecture[edit]

According to Cisco's product literature, IOS XR shares very little infrastructure with the other IOS trains, and is instead built upon a "preemptive, memory protected, multitasking, microkernel-based operating system".[1] The microkernel was formerly provided by QNX[2]; versions 6.0 onwards use the Wind River Linux distribution.[3]

IOS XR aims to provide the following advantages over the earlier IOS trains:

  • Improved high availability (largely through support for hardware redundancy and fault containment methods such as protected memory spaces for individual processes and process restartability)
  • Better scalability for large hardware configurations (through a distributed software infrastructure and a two-stage forwarding architecture)
  • A package based software distribution model (allowing optional features such as multicast routing and MPLS to be installed and removed while the router is in service)
  • The ability to install package upgrades and patches (potentially while the router remains in service)
  • A web-based GUI for system management (making use of a generic, XML management interface)

History[edit]

IOS XR was announced along with the CRS-1 in May 2004.[4] The first generally available version was 2.0. The most recent release is version 6.0[5] which was released on 23 December 2015.

Other significant releases include the following.

  • 3.2 – first generally available version for the 12000 router series
  • 3.9 – first generally available version for the ASR9000 series
  • 5.0 (20 September 2013) – first generally available version for the NCS6000 series, which is based upon a Linux kernel[6]
  • 6.1.1 - Introduces support for the 64-bit Linux-based IOS XR operating system on ASR9000 series [7]

Differences between IOS and IOS XR[edit]

Example BGP configuration for both IOS and IOS XR. More examples can be found in the Cisco document Converting Cisco IOS Configurations to Cisco IOS XR Configurations.[8]

! Cisco IOS
!
router bgp 109
  no synchronization
  bgp log-neighbor-changes
  neighbor 203.0.113.1 remote-as 109
  neighbor 203.0.113.1 update-source Loopback0
  no auto-summary
!
! Cisco IOS XR
!
router bgp 109
  neighbor 203.0.113.1
    remote-as 109
    update-source Loopback0
  !
!


References[edit]

External links[edit]