OSI 7-layer model

Application layer: provide network services for applications.

Presentation layer: provides encoding and conversion functions for application layer data.

Session layer: responsible for establishing, managing and terminating communication sessions between presentation layers.

Transport layer: provides error detection before connection oriented or non connection oriented data transmission and retransmission.

Network layer: provide the router with a logical address to determine the path.

Data link layer: It controls the communication between the network layer and the physical layer.

Physical layer: transfers bit streams between devices.

TCP/IP five layer model

Application layer: BGP, DHCP, BFD, SNMP, MPLS LDP and other protocols.

Transport layer: TCP, UDP and other protocols

Network layer: mainly IP protocols, as well as IPSec, GRE, VRRP, OSPF, ICMP, PIM, IGMP and other protocols.

MPLS layer: MPLS, ARP, LACP, STP/RSTP/MSTP, IS-IS and other protocols.

Link layer: VLAN, PPPoE, PPP, HDLC and other protocols