Cisco IOS-XE processes.

[Mitrixsen]

Hello, everyone.

I need some clarification when it comes to IOS XE. The device runs a Linux Kernel. On top of this Linux Kernel, the IOS runs as its own process - IOSd.

Now, within this process, do further processes such as routing and switching run or how is it? My resources says that the IOSd process runs features such as routing, switching, and network management. Then they say that key services such as packet forwarding, security, and network management are separate processes, so how exactly is it, please? What runs inside of what and what is its own process?

Thank you
David

[bigevilbeard]

@Mitrixsen your understanding is correct, IOSd is the brains for those features, the heavy lifting and grunt work (forwarding) and the secure access (management) are deliberately placed in separate, independent processes. I read somewhere that Cisco took the old, monolithic IOS, then wrapped it in a process IOSd, and then broke out the performance, critical and platform, and specific services into separate, more robust Linux processes.

Hope this helps!

[Mitrixsen]

Thank you!

I understand that IOSd is the core to all this. However, all the other processes related to forwarding, management, and so on, are they considered sub-processes of IOSd or how is it with them?

David

[bigevilbeard]

@Mitrixsen as i am to understand, no. the other processes related to packet forwarding, security, and system management are not considered sub-processes or child processes of IOSd. It does provides the intelligence/control plane to the separate processes, but it does not own them in the process hierarchy itself.

[M02@rt37]

They are not subprocesses of IOSd. IOSd is just one Linux process for the control plane, while all forwarding, security, and mgmt components run as separate, independent linux processes that communicate with IOSd via internal APIs.

[M02@rt37]

Hello David,

IOSd provide the control plane in a single monolithic process...while IOS-xe use multiple independent linux processes for forwarding and advanced services...

[M02@rt37]

This cisco live presentation: https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2024/pdf/BRKARC-2092.pdf describe exactly that separation of processes in Cisco IOS-XE.