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 is provided by QNX.
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)
Read more about this topic: IOS XR
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