Cisco IOS XR


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

Architecture

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". The microkernel was formerly provided by QNX; versions 6.0 onwards use the Wind River Linux distribution.
IOS XR aims to provide the following advantages over the earlier IOS trains:
IOS XR was announced along with the CRS-1 in May 2004. The first generally available version was 2.0. The most recent release is version 6.5.3 which was released in March 2019.
Other significant releases include the following.
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.

! 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
!