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6.5 Describe the function of management, data, and control planes in a network device

Data Plane

  • determines how the incoming packet on a port must be forwarded to an outgoing port based on values in packet header
  • router uses techniques such as fast switching or CEF switching

Control Plane

  • determines how a packet is routed among routers or other network elements as packet goes from source to host
  • deals with packets that are destined for the router itself
  • device and network management
  • management functions: initializes interfaces with default config, IP addreses, user accounts, etc

The issue with this setup is that the network engineer/admin needs to manage each device individually.

Centralized Control Plane

The solution is to use a network controller. The move the control planes from each network device and consolidate them in the controller.

  • communication is done via APIs
  • Southbound APIs: network controller interacts with the network devices
  • Northbound APIs: network elements interact with network controller

SDN Controllers

  • the "brain" in modern networks
  • architecture that decouples the network control and forwarding functions which enables the network control to become directly programmable
  • abstracts the underlying infra
  • knows about all network devices and best paths between them
  • 2 controllers:
    • OpenFlow: ONF manages this standard used for comm between SDN controller and managed network devcies
    • OpenDayLight: Linux foundation manages this standard uses OpenFlow to manage network devices
  • 3 layers:
    • Infrastructure layer: physical layer composed of networking equipment and elements
    • Control layer:
      • where the SDN controllers reside to control network infra.
      • keeps topology details and network logic for routing, switching, VPN, firewall security rules.
      • exposes APIs to upper layers
      • Northbound interface: used for comm with application layer via REST API
      • Southbound interface: used for comm with infra layer via OpenFlow, NETCONF
    • Application layer: network automation, configuration, management, montoring