Beyond Centralization: The Local Control Plane

We tend to place our focus on the centralized management and control plane, but they are distributed, existing in both a centralized component (the NSX Manager for the management plane, the multi-node controller cluster for the Centra Control Plane), and a distributed component in the Management Plane Agent (MPA) and Local Control Plane (LCP) agents installed on the nodes.

The MPA communicates with NSX Manager over a RabbitMQ channel, and has a couple of purposes:
• Bootstrapping the Transport Node
• Forwarding statistics to NSX Manager

It also works with a service, nsxa, that brokers any communications to and from the kernel.

The LCP is simply the host-local control plane agent – netcpa. We should be familiar with netcpa from NSX-V. We use a proprietary protocol to communicate between netcpa and the controller nodes that uses TCP/1234. On KVM hosts, netcpa is paired with the nsx-agent service to cover the local control plane duties, including programming OVS and ConnTrack for L2, L3, and DFW services.

The LCP is bootstrapped by the Managment Plane Agent (MPA), and is responsible for programming the data plane, as we need a user space broker to communicate to the kernel modules installed on the hypervisor.

The LCP is installed as part of the host preparation process when we add Fabric Nodes to NSX Manager, and is responsible for L2 and L3 control data – things like VNIs, VTEP, MAC, and ARP tables, etc. The LCP programs the DFW as well, and6  also contains VIF (Virtual Interface) status and other such information.

These are critical to the healthy operation of NSX-T.

 

~$ history
Introduction: From NSX-V to NSX-T. An Adventure
NSX-T: The Manager of All Things NSX
The Hall of the Mountain King. or “What Loot do We Find in nsxcli?”
Three Controllers to Rule Them All (that just doesn’t have the same ring to it, does it?)

 

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