To gain an understanding of components that make up networks we’ll start by stating that a network is a combination of tools working together to provide connectivity to endpoints.
Let’s list the tools.
Network Device (Switch and Router and others) – This is a device which terminates multiple cables into itself with the other end of the cable being other devices. The network device interconnects multiple endpoints via its ports on which cables terminate.
Protocols – These are tools which provide for a coordination mechanism. This coordination mechanism is an exchange of information which makes possible the exchange of traffic.
Protocol Messages – These are messages exchanged between Protocols while they coordinate the laying of the network foundations for exchange of traffic.
Addresses – These come in many flavours and are intended to identify the source and destination of a data payload which is traversing the network. They can be layered/structured for aggregation and division pools.
Lookup – This is done on the various addresses to find the next hop. Lookup is done to find the next point to which to send the data payload to so that it reaches its ultimate destination after traversing the network.
Appended Information – This is a general term which encompasses information traversing the network which is other than payload and addresses. These are information and tools which are put into packets for protocol operations. This is information inside headers other than the addresses.
Identity Tags – This is a specific class of Appended Information which provides for identity functionality during a lookup and for identification and separation of protocol functions.
Filters & Actions – These are deployed on the network devices to provide intelligent selection and resulting actions over the traversing data payload. They utilize the addresses and appended information inside the data payloads and also the headers.
Network Over Network – This is a general term for a network on top of a network for provision of separate connectivity. A combination another layer of protocols and addresses result in a network over a network.
Network + Network – This is a term identifying the interconnection of 2 or more separate networks resulting in a larger network. Also called internetwork it signifies one domain interconnected to another domain.
Control and Data Plane – Control Plane is the network protocols laying the network foundations and data plane is the traffic traversing the network. Control Plane enables Data Plane.
Network Inside Network Device – This is a term signifying the division of a network device to facilitate a software separation in networks. It creates separate networks inside a network device via operating system software constructs.
We can put brands on these:
OSPF/ISIS/BGP are Protocols to lay the Control Plane for IP addresses
LDP is the Protocol to lay the control plane for MPLS addresses (labels)
MAC Address / IP Address / MPLS Labels are addresses and Lookups are done on them during Data Plane operation
MPLS L2 VPN / MPLS L3 VPN are a Network Over Network function based on labels.
MP-BGP is a protocol to lay Control Plane for Network over Network (MPLS L2VPN & EVPN)
AS to AS BGP connectivity is a Network + Network function
Route Maps / Prefix Lists / AS Path Lists are part of Filters and Actions
OSPF Areas and ISIS Levels are a Network domain + Network domain layering type function
QoS Diffserv and CoS are appended information for actions and functionalities
EVPN, OTV & VXLAN are Network over a Network options. These provide a network over a network Control Plane and network over a network Data Plane.
VXLAN VNID / VLAN TAG / Route Target / Route Distinguishers / BGP Communities are Identity tags for protocol operations where they aid the control plane or data plane.
VDC / VRF / EVPN EVI are Network inside Network Device features primarily being operating system software constructs.
This is a rough approach with much simplification but is intended to view the various network components as tools providing functionality working in unison for connectivity provision. This view aids looking at the components from a Design perspective.
Whether it is a Service Provider, Enterprise or Data Center / Cloud IaaS network the components interact and provide functionality.