Lower Networking vs Upper Networking

Lower Networking vs Upper Networking

• Lower networking:
  • network engineering.
  • includes physical network topology, routing protocols, network device configurations (routers, switches, firewalls, etc.), automation, etc.
  • comprises both underlay (VLAN) and overlay, i.e. VXLAN.
• Upper networking:
  • software engineering.
  • exists "on top of" the lower network .
  • includes virtual machine and container networking, kubernetes networking, service mesh, load balancing, DNS, etc.

Underlay vs Overlay

Both are part of "Lower Networking".

• Underlay: physical network (comprise switches and routers).
• Overlay: virtual network on top of physical network, using a virtual interface such as Virtual Extensible LAN (VXLAN).
  • EVPN: control plane.
  • VXLAN: tunnel technology.
  • EVPN and vxlan go hand in hand.

Encapsulated Networks vs Unencapsulated Networks

Encapsulated Networks: encapsulates a logical Layer 2 network over an existing Layer 3 network topology, which covers multiple Kubernetes nodes. Layer 2 network is isolated so there is no need for routing distribution.

Unencapsulated Networks: provides a Layer 3 network for routing packets between containers. There is no isolated Layer 2 network or overhead, but this is at the expense of Kubernetes workers, which must manage any required route distribution. A network protocol is implemented to connect Kubernetes workers and use BGP to distribute routing information to pods.

CNI networks can be implemented using an encapsulated or unencapsulated network model.

• VXLAN is an example of an encapsulated model
• Border Gateway Protocol (BGP) is an example of an unencapsulated model.