A denial of service attacks are usually employed to interrupt the system's activity by getting a large number of fake requests, which leads to slowing down and stopping information system or network operations. This paper outlines the basic principles of DDoS attacks, explains how DDoS attack works. The paper presents an experimental using OPNET simulation tool in which traffic from three different applications VoIP, FTP, and HTTP is used to make the practical model with a firewall shield to model and simulate DDoS over Internet. However, three scenarios have been developed to illustrate different aspects of the DDoS over networks. The results clearly demonstrate how firewalls can be configured to mitigate DDoS attacks
Azeddien M. Sllame, Reema A. Saed, Mariam Abojella Msaad(5-2021)

This paper describes the usage of OPNET simulation tool to evaluate VoIP over MPLS networks which employs RSVP protocol as QoS mechanism with SIP or H.323 as signaling protocols for setting up VoIP calls over the Internet. The results showed that the H.323 with RSVP over MPLS networks produced minimal end-to-end delay than SIP protocol; making it a good choice as a signaling protocol with VoIP over MPLS networks for places requiring minimal end-to-end delay, while SIP reported lowest delay jitter with minimal call setup time
Azeddien M. Sllame, Asra Hema, Huda Alnajem(3-2018)

Multipath Transmission Control Protocol (MPTCP) has been proposed by the Internet Engineering Task Force (IETF) working group, in order to get benefit of the interfaces in the network devices, as most of these network devices are equipped with more than one interface. MPTCP splits a single data stream across multiple paths. This has obvious benefits for reliability, and it can also lead to more efficient use of network resources. The main aim of this paper is to study the main mechanism of the MPTCP and some of the multipath transmission protocols. arabic 5 English 43
Mariam Abojela Msaad, Taha Arabi , Amer R. Zerek(1-2013)