Maximum Burst Size of Traffic Determination for Switched Local Area Networks

Maximum Burst Size of Traffic Determination for Switched Local Area Networks

Monday O. Eyinagho (Covenant University, Nigeria) and Samuel O. Falaki (Federal University of Technology, Nigeria)
Copyright: © 2015 |Pages: 12
DOI: 10.4018/978-1-4666-5888-2.ch612
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Background

In the context of service provisioning, the Internet supports the guaranteed and controlled-load services. While the guaranteed services class is designed for real-time traffics that need guaranteed maximum end-to-end delays, the controlled-load services class is designed for traffics that does not require this guarantee, but are, nevertheless, sensitive to, overloaded networks, and to the danger of losing packets. A file transfer session is an example of traffic that does not need real guarantee, while real-time audio and video transfers are examples of traffic that needs real guarantees. Both classes of services operate on the principle of ‘admission control’, in which a flow is set-up, which must conform to the IETF’s (Internet Engineering Task Force’s) T-SPEC. The admission control principle operates as follows: (Le Boudec & Thiran, 2004, p.75)

  • In order to receive either type of service, a flow must first perform a reservation during a flow set-up.

  • A flow must conform to an arrival curve of the form σ(t) = min (M + pt, rt + b). In Intserv (Integrated Services) jargon, the 4-uple (p, M, r, b) is called a T-SPEC or traffic specification. In order words, the T-SPEC is declared during the reservation phase. Here, M = maximum packet size, p = peak rate, b = burst tolerance, r = sustainable rate.

  • All routers along the path accept or reject the reservation. With the guaranteed service, routers accept the reservation only if they are able to provide a service curve guarantee and enough buffer for loss-free operation. The service curve is expressed during the reservation phase.

Key Terms in this Chapter

Excess Information Rate (EIR): Specifies the average rate up to, which, excess Service Frames (frames whose average rate > CIR or Committed Information Rate) are admitted into the provider’s network. These Service Frames are not CIR-conformant, and are hence, delivered without any performance objectives.

Excess Burst Size (EBS): Specifies the maximum number of bits allowed for incoming Service Frames to be EIR-conformant; for every connection, an EBS is defined. It is also defined as the maximum number of bits in excess of the Committed Burst Size (CBS) that a user can send during a predefined time period.

Maximum End-To-End Delay: This is the sum of the maximum delays experienced by a packet at each hop (node) on its path from origin node to destination node.

Maximum Burst Size: The maximum amount of traffic in bits that can be sent or transmitted in a burst.

Access Rate: (in bits per second) The definition for every connection depends on the bandwidth of the channel connecting the user to the network; the user can never exceed this rate. For example, if the user is connected to a Frame Relay network by T-1 line, the access rate is 1.544 Mbps and can never be exceeded.

Communication Subnet: This is the aspect of a MAN/WAN that consists of transmission lines, interconnected by switching elements – essentially routers and layer-3 switches.

Carrier Ethernet Network: This is the communication subnet for providing Ethernet services to customers.

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