1. Anilkumar Dantu CCIE (22536)
IOS XR Introduction
Anilkumar Dantu CCIE (22536)
HTTS, Cisco Systems

2. IOS XR Introduction - Agenda
Carrier Grade NOS Features Expectation and OS Concepts
Welcome to XR OS
XR OS packaging
XR OS installation
Configuration in XR OS
Troubleshooting in XR

3. Carrier Grade NOS Feature Expectations
Scalability
High Availability
Security
Flexibility
It is not that IOS does not meet these expectations. Only extent to which it can meet these expectations in future was getting challenged due to its OS structure.

4. OS terminologies
Operating system, Kernel , CPU , memory , I/O , Applications , processes etc OS OS
Monolithic Kernel
Micro kernel

5. Distributed subsystems/processes Memory-protected microkernel
Welcome to XR OS
Core OS Capabilities(QNX Based Micro Kernel)
- Protected process memory space
- Preemptive Scheduling
- Plane separation & fault
isolation
Distributed subsystems/processes
Microkernel
Scheduling
IPC mech.
Memory mgmt.
H/W abstraction
BGP
RIP
IS-IS
OSPF
Routing Policy
PIM
IGMP
RIB
L2 Drivers
ACL
FIB
QoS
LPTS
Host Services
PFI
Interfaces
Data plane
CLI
SNMP
XML
Netflow
Alarm
Perf. Mgmt.
SSH
Management plane
Control plane
Control Plane
Routing policy
L2 drivers
Host services
Perf. mgmt.
System services
Memory-protected microkernel

6. Welcome to XR OS contd… More than 200+ Processes.
Checkpoint support for process
Restart and process level Redundancy

7. IOS Vs XR OS IOS XR Kernel Monolithic Micro kernel Memory Shared
Protected
Scheduling of process
Priority based- Non-preemptive
Priority based- preemptive
Process stop/restart No
Yes
Modular architecture
Services running mode
Kernel mode
Application/user space mode

8. XR OS packaging
Inline with its software architecture XR OS Software is available as a modular package. On CCO we can download XR OS in form of Tar file eg : XR12000-iosxr tar
Once file is untarred – we see Cisco IOS XR Bootable Files, PIEs, and SMUs

9. XR OS packaging contd… Cisco IOS XR Bootable Files, PIEs, and SMUs
Files ending with .vm extension are bootable files. VM file contains – operating system kernel , Base image , admin plane functions , routing & forwarding bundles. VM files is used to boot router during fresh installation or as last resort recovery. Installation of the .vm image file results in the installation of a number of individual packages.
PIE (Package installation envelope) : Upgrade packages,
Optional additional packages
SMU (software Maintainence units) : These are fixes
Or patches for Bugs. Eg- c CSCto40258.pie
MPLS
MCAST
MGBL
SEC
Mandatory
Optional
OS-MBI
Base
Admin
Forwarding
Line card
Routing

10. XR OS Installation
In XR TURBO-BOOT refers to booting of Router from ROMON mode.
TURBO-BOOT is required during IOS to XR conversion or recovery of router from ROMON mode.
TURBO_BOOT steps:
- First step is to verify existing ROMON settings by querying it using “set” command
-you can use “unset Variable” command to clear existing settings
-Second step is to set the TURBOBOOT variable in ROMON to a non-volatile storage where .vm file is stored.
- Last step is rommonB7> boot disk0:c12k-mini.vm-4.1.0

11. XR OS Installation contd…
- With TURBOBOOT variable in ROMON set to “on” and boot command starts the TURBOBOOT process. Here XR OS is loaded into memory & after verification of disk space ,OS is copied to the disk.
Once OS is copied to disk , boot variable is set to disk0: product_osmbi_4.1.0/product-rp.vm & config register is set to 0x102. After that node is reloaded to boot from disk0: the new boot variable. This completes the TURBOBOOT process.
Once installation of XR OS is complete and we can verify the details using commands
show install active summary
show version
Installation/booting with .vm file give only basic routing & forwarding capability. For additional capability you need to install specific PIE files.
Install add disk0:package_name.pie activate

12. XR Hardware Requirements
From XR OS installation procedure we have seen flash disk (disk0: , disk1:) is used extensively for loading XR image , config files (running configs , roll back configs) , PIEs , SMUs etc. So pulling out flash disk from running node will make node unresponsive/reload.
Make sure RP cards has appropriate disk space available , RP & LC hardware are compatible with XR as OS, and also verify the RP, LC has minimum firmware (romon, fpd) level to boot up in XR.
Many of the XR supporting nodes RP cards will have a harddisk (40GB or more) used basically for archiving of logs, dump files , additional sw packages.

13. XR Configuration & files
- In XR there is no differentiation as startup-config & running config as in IOS.
- In XR configuration is divided into Admin plane , share plane & local plane. Hence the configuration file structure is also developed to support it.
Here running configuration is stored in binary format (known as primary persistent configuration) as compared to ASCII format of startup/running config in IOS. Configuration file stored in binary format helps in faster loading during bootup. And added features of commit reference points, rollback is made possible.

14. XR Configuration (Two stage commit)

15. Troubleshooting in XR RP & LC states. Logs & storing of wrapped logs,
Show tech files
Traces captures
Process crash traceback decodes