Differences between Circuit, Packet and MPLS switching
What are differences between Circuit, Packet and MPLS switching? Switching is a process of determining of the logical path, how data would travel between sender and receiver. Three main methods, that are commonly used in modern networks are: circuit switching, packet switching, and multiprotocol label switching.
Main feature of the circuit switching, is the connection that is being established before any data would be transmitted, and it would remain up until the transmission is over. All the data follow the same path, in exact order. Most common example of this connection in our everyday life is the traditional telephone. Since the connection is opened for the whole time data is being transmitted, the bandwidth in the path between sender and receiver is constantly reserved and is not available for any other application or service. That makes huge waste of resources in situations when the connection is up, but no data is actually being transmitted. Circuit switching is perfect option for video or audio streaming, where data need to be sent constantly, and there is no time for packet reorganisation at the receiver end.
Circuit switching has its flaws, which are overcomed in packet switching, which makes it the most popular method of connecting nodes on the network. Unlike circuit switching, packet switching breaks data into packages and sends them separately to the receiver. Each packet is free to choose its own path to the destination, where they all will be assembled back to the data message. It doesn’t matter in which order they arrive to the destination, since they have information about the sequence they should be assembled. At the destination node, data gets reassembled based on this information. Since, reassembling of data takes time, this method of switching cannot be used for video or audio streaming, due to necessity of instant data availability on the arrival to destination.
Packet switching is popular due to ability not to waste bandwidth and use it only for the packet transmission. These factors make packet switching the main solution for the Internet and Ethernet networks.
MPLS (Multiprotocol Label Switching)
MPLS allows different Layer 3 protocols to travel over any connection-oriented Layer 2 protocols. It enables it to use packet-switched technologies over the circuit-switched networks. Unlike the IP-based network, MPLS adds its labels on the first router to the Level 3 datagram. After that, Level 2 header is added as shown in Figure 1. MPLS headers provide addressing and prioritization information, that allows for faster data transmission which results in better QoS (Quality of Service).
Figure 1. MPLS within frame.