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MPLS TC multiprotocol label switching traffic class

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MPLS (Multiprotocol Label Switching) is a networking technology that enables the creation of virtual networks over existing physical networks. It was designed to provide a more efficient and flexible way of forwarding network traffic, compared to traditional IP-based routing. MPLS achieves this by introducing a new label-based forwarding mechanism, where packets are assigned a label that identifies the path they should follow through the network. MPLS also introduces the concept of Traffic Engineering (TE), which allows network administrators to control the flow of traffic in the network and optimize the use of network resources.

One of the key features of MPLS is the ability to define and enforce Quality of Service (QoS) policies. QoS is a set of mechanisms that allow network administrators to control the priority, bandwidth, and latency of different types of traffic flowing through the network. In MPLS, QoS is achieved by using Traffic Classes (TCs) and Differentiated Services (DiffServ) code points. In this article, we will focus on MPLS TCs and how they are used to provide QoS.

What is MPLS TC?

MPLS Traffic Class (TC) is a mechanism used to differentiate different types of traffic flowing through the MPLS network. It allows network administrators to assign a specific class of service to a group of packets based on their QoS requirements. MPLS TC is a 3-bit field in the MPLS header that identifies the class of service assigned to a packet. The value of MPLS TC ranges from 0 to 7, where 0 is the default value and 7 is the highest priority.

MPLS TC can be used to provide several QoS features, including:

  1. Traffic classification: MPLS TC allows network administrators to classify traffic based on its QoS requirements. For example, real-time traffic such as voice and video can be assigned a higher priority compared to non-real-time traffic such as email and web browsing.
  2. Traffic conditioning: MPLS TC can be used to condition traffic by limiting the bandwidth or shaping the traffic to conform to a specific QoS policy.
  3. Traffic scheduling: MPLS TC can be used to schedule traffic by assigning it to a specific queue or forwarding class based on its QoS requirements.

How does MPLS TC work?

MPLS TC works by assigning a specific class of service to a group of packets based on their QoS requirements. This is achieved by setting the MPLS TC field in the MPLS header to a specific value. When a packet enters the MPLS network, the MPLS router examines the MPLS header and forwards the packet based on its MPLS TC value. The MPLS router can use several mechanisms to forward the packet based on its MPLS TC value, including:

  1. Traffic conditioning: The MPLS router can condition the traffic by limiting its bandwidth or shaping the traffic to conform to a specific QoS policy. This is achieved by using mechanisms such as traffic policing, traffic shaping, or queue management.
  2. Traffic scheduling: The MPLS router can schedule the traffic by assigning it to a specific queue or forwarding class based on its MPLS TC value. This is achieved by using mechanisms such as priority queuing, weighted fair queuing, or class-based queuing.
  3. Traffic engineering: The MPLS router can use traffic engineering to optimize the use of network resources by selecting the best path for the traffic based on its MPLS TC value. This is achieved by using mechanisms such as explicit routing, link-state routing, or path computation.

MPLS TC and Differentiated Services (DiffServ)

MPLS TC is closely related to Differentiated Services (DiffServ), which is a mechanism used to provide QoS in IP-based networks. DiffServ uses a 6-bit field in the IP header called the Differentiated Services Code Point (DSCP) to identify the QoS requirements of a packet. The DSCP field is used to mark the packet with a specific code point that corresponds to a specific QoS policy. The code point is then used by network devices to classify and prioritize traffic based on its QoS requirements.

MPLS TC and DiffServ are complementary mechanisms used to provide end-to-end QoS in a network. MPLS TC can be used to provide QoS within the MPLS network, while DiffServ can be used to provide QoS in the IP-based networks that connect the MPLS network. In this way, MPLS TC and DiffServ can work together to provide end-to-end QoS.

MPLS TC and Traffic Engineering (TE)

MPLS TC can also be used in conjunction with Traffic Engineering (TE) to optimize the use of network resources. TE is a mechanism used to control the flow of traffic in the network and optimize the use of network resources. TE allows network administrators to select the best path for traffic based on its QoS requirements.

MPLS TC can be used to identify the QoS requirements of a packet, while TE can be used to select the best path for the packet based on its QoS requirements. This allows network administrators to optimize the use of network resources by selecting the best path for traffic based on its QoS requirements.

Conclusion

MPLS TC is a mechanism used to differentiate different types of traffic flowing through the MPLS network. It allows network administrators to assign a specific class of service to a group of packets based on their QoS requirements. MPLS TC can be used to provide several QoS features, including traffic classification, traffic conditioning, and traffic scheduling.

MPLS TC is closely related to Differentiated Services (DiffServ), which is a mechanism used to provide QoS in IP-based networks. MPLS TC and DiffServ can work together to provide end-to-end QoS in a network.