» Research Areas > Network Simulations > DiffServ QoS in NS-2 Simulator 26 October 2020

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QoS developed Bandwidth broker functionality for NS-2

 Bandwidth Broker models
Admission Control Algorithms

Bandwidth Broker(BB version 1.0)
Our team has developed an application which plays the role of a Bandwidth Broker(BB). The BB framework has a BB base agent and many BB edge agents. When an edge agent asks for bandwidth, and if the BB base is available, the BB base asks each one of the bandwidth path edges if they have the requested bandwidth. First asks the first edge. If the Bbbase gets a positive answer continues with the second one. If all edges are o.k., then BB base sends them a command to fix the bandwidth otherwise the request is rejected.

Central Bandwidth Broker(BB version 1.1)
This BB is a new implementation of the previous version of our BB. When the simulation starts, BB edges send an information packet about their capabilities to the BB base. BB base takes these packets and creates a database. So when a request comes , he checks immediately his database. If the database answers positive ,then the BB base sends to the edges the command to fix the bandwidth otherwise the request is rejected. We also have created a log-file like system about the situation of the requests.

Distributed Bandwidth Broker(BB version 1.1)
This BB is also a new implementation of the previous version of our BB. Here, when a request comes , BB base asks immediately all the edges for bandwidth. When the first negative answer comes ,the request is rejected and only when all the edges answered yes the request is satisfied. We create a database to control our question packets. We check if the answer packet the BB base receives is valid because BB base may receive an answer packet from a BB edge agent about a request that has been already rejected. That packet is simply ignored.

Central Distributed Bandwidth Broker(BB version 1.1)
This BB includes all the benefits of both the central and the distributed model. The requests are processed just like the central model with the difference that it stores the database information both into his database and at the edges.

Simple admission control (SAC)
Each incoming request is examined by itself, and is accepted if there is still available bandwidth for the service.

Price-based admission control (PBAC)
The algorithm makes a decision on which requests will be accepted trying to optimize the network utilization by gathering and evaluating multiple requests together.

Adaptive admission control (AAC)
Tries to gather multiple requests and evaluate them together for purposes of increasing the resource utilization, but also uses an adaptation module in order to keep processing requirements low.

Adaptive admission control with resubmissions (AACR)
An enhanced version of the AAC algorithm, it has the capability to recognize previously rejected requests and increase their priority.

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