In recent years, the demand for telecommunication services has shifted from voice (SMS) to data services. At the same time, the technology in mobile communication (Mobile Communication) has also been completely changed, such as the core network (Core Network) has been changed from Circuit Switching (CS) to Packet Switching (PS), the transmission network (Transmission Network). Changed from TDM (E1 / T1, PDH / SDH…) to IP / MPLS.
- TDM (Time Division Multiplexing) or Circuit Switching (CS), ATM (Asynchronous Transfer Mode) is a connection-oriented type of data transmission that requires the creation of a logical path for dedicated data transmission (dedicated time slot).
- IP (Internet Protocol) or Packet Switching (PS) is a type of connectionless data transmission that does not require the creation of a logical path before transmission.
- MPLS or Multi-Protocol Label Switching combines two transmission technologies: connectionless, which is used in the control plane, and connection-oriented, which is used in the forwarding plane.
- MPLS functions in a layer that is generally considered to be between the second layer (L2 data link layer) and the third layer (L3 network layer) of the OSI model, and is therefore often referred to as Layer 2.5 protocol that can pack packets from many different protocols, such as IP, ATM, SDH / SONET, Ethernet frame, DSL,.. etc.
- In an IP network, packets are forwarded by the router on a hop-by-hop basis through the target IP address of the packet and the path. To go to the next (hop) existing in the router's routing table.
- In MPLS networks, a label is used to forward data packets instead of an IP address, i.e., the data is transmitted over a pre-defined path between the transmission source and the destination. The number plates attached to the data will be switched (label switched) by the routers on the LSP (label-switched paths) where the data must pass through. These routers are called LSR (label switch routers).
- A label forwarding table lists the list of label values, each of which is connected to the interface interface for the next hop. Faster and better QoS (Quality of Service).
- In MPLS, the forwarding packets are divided into different FEC (Forwarding Equivalent Class) classes. Any data packets with the same FEC class will be treated equally in the MPLS network transmission.