**Optical Communications Systems: Network Traffic**

244 Optical Communications Systems

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2596-2604.

**10** 

*India* 

**Traffic Engineering** 

*Shrinathji Institute of Technology & Engineering, Nathdwara (Rajasthan),* 

*Multi Protocol Label Switching (MPLS) is today mostly used for traffic engineering therefore we* 

Traffic engineering and fast reroute are the two major applications of constraint based routing Traffic engineering is the process of controlling how traffic flows through a service provider's network so as to optimize resource utilization and network performance[1]. Traffic engineering is needed in the Internet mainly because the shortest path is used in current intra- domain routing protocols (e.g., OSPF, IS-IS) to forward traffic. The shortest

**First**, the shortest paths from different sources overlap at some links, resulting in congestion

**Second**, at some time, the traffic volume from a source to a destination could exceed the capacity of the shortest path, while a longer path between these two nodes remains underutilized. The reason why conventional IP routing cannot provide traffic engineering is that it does not take into account the available bandwidth on individual links. For the purpose of traffic engineering, constraint based routing is used to route traffic trunk[2], which is defined as a collection of individual transmission control protocol (TCP), or user datagram

*start by describing what traffic engineering is and why traffic engineering is needed.* 

protocol (UDP) flows, called "microflows" that share two common properties.

The **first** property is that all microflows are forwarded along the same common path.

The **second** property is that they all share the same class of service. By routing at the granularity of traffic trunks, traffic trunks have better scaling properties than routing at the granularity of individual microflows with respect to the amount of forwarding state and the

In a sense, IP networks manage themselves. A host using the Transmission Control Protocol (TCP) adjusts its sending rate according to the available bandwidth on the path to the receiver. If the network topology should change, routers react to changes and calculate new paths to the destination. This has made the TCP/IP [3] Internet a robust communication network. But robustness does not implicate that the network runs efficiently. The interior gateway protocols used today like OSPF and ISIS compute the shortest way to the destination and routers forward traffic according to the routing tables build from those calculations. This means that traffic from different sources passing through a router with the same destination will be

**1. Introduction** 

at those links.

volume of control traffic.

path routing may give rise to two problems.

Mahesh Kumar Porwal
