**8. Requirements for traffic engineering model**

A TE process model must follow a set of actions to optimize the network performance. This model has the following components:

**Measurement:** Measurement is an important component of the TE function. The network performance can only be determined through measurement. Traffic measurement is an essential tool to guide the network administrator of large IP networks in detecting and diagnosing performance problems, and evaluating potential control actions. The data measurement is analyzed and a decision based on the analysis is taken for network performance optimization. Measurement is needed to determine the quality of services and to evaluate TE policies.

**Modelling, Analysis, and Simulation:** Modelling and analysis are important aspects for TE. A network model is an abstract representation of the network that captures the network

1. The head-end router requests LSP establishment using a dedicated signaling protocol. As is often the case, two protocols were designed to provide the same functionality as RSVP-TE (RSVP extensions for traffic engineering) and CR-LDP (constraint-based

2. The routers along the path accept (or reject) the MPLS TE LSP establishment request

3. When all the routers in the path accept the LSP signaling request, the MPLS TE LSP is

4. The head-end router can use MPLS TE LSP to handle special data (initial implementations only supported static routing into MPLS traffic engineering tunnels)

The tight integration of MPLS traffic engineering with the IP routing protocols provides an important advantage over the traditional Layer 2 WAN networks. In the Layer 2 backbones, the operator had to establish all the virtual circuits across the backbone (using a network management platform or by configuring switched virtual circuits on edge devices), whereas the MPLS TE can automatically augment and enhance the mesh of LSPs already established based on network topology discovered by IP routing protocols. You can thus use MPLS traffic engineering as a short-term measure to relieve the temporary network congestion or

In recent years, MPLS traffic engineering technology (and its implementation) has grown

1. **Fast reroute** provides temporary bypass of network failure (be it link or node failure)

2. **Re-optimization** allows the head-end routers to utilize resources that became available

3. **Make-before-break** signaling enables the head-end router to provision the optimized

4. **Automatic bandwidth adjustments** measure the actual traffic sent across an MPLS TE

A TE process model must follow a set of actions to optimize the network performance. This

**Measurement:** Measurement is an important component of the TE function. The network performance can only be determined through measurement. Traffic measurement is an essential tool to guide the network administrator of large IP networks in detecting and diagnosing performance problems, and evaluating potential control actions. The data measurement is analyzed and a decision based on the analysis is taken for network performance optimization. Measurement is needed to determine the quality of services and

**Modelling, Analysis, and Simulation:** Modelling and analysis are important aspects for TE. A network model is an abstract representation of the network that captures the network

and set up the necessary internal MPLS switching infrastructure.

as a network core optimization tool without involving the edge routers.

well beyond features offered by traditional WAN networks. For example:

comparable to SONET/SDH reroute capabilities.

LSP before tearing down the already established LSP.

**8. Requirements for traffic engineering model** 

LSP and adjust its reservations to match the actual usage.

after the LSP was established.

model has the following components:

to evaluate TE policies.

or seamlessly integrate the new path into the link-state routing protocol.

routing using label distribution protocol).

operational.

features, attributes and characteristics (e.g. link and nodal attributes). A network model can facilitate analysis or simulation, and thus can be useful to predict the network performance.

Network modelling can be classified as structural or behavioural module. Structural modules focus on the organization of the network and its components. Behavioral modules focus on the dynamics of the networks and its traffic workload. Because of the complexity of realistic quantitative analysis of network behavior, certain aspects of network performance studies can only be conducted effectively using simulation.

**Optimization:** Network performance optimization can be called corrective when a solution to a problem is made, or perfective, where an improvement to the network performance is made, even when there is no problem. Many actions could be taken such as adding additional links, increasing link capacity or adding additional hardware. Planning for future improvement in the network (e.g. network design, network capacity or network architecture) is considered as a part of network optimization.
