Manodha Gamage

Implementation of virtual path hopping (VPH) as a solution for control plane failures in connection oriented networks and an analysis of traffic distribution of VPH

A connection oriented next generation Internet could guarantee the QoS preferred by the emerging real time applications. These connection oriented networks are inherently more prone to network failures: link/path failures and degraded failures. The control and the data plane of connection oriented networks such as MPLS are logically separated. Therefore a failure in the control plane should not always immediately affect the communications in the data plane. Control plane failures are usually detected using Timers. If any of the Timers expire, the control plane session is terminated resulting failures in the corresponding data plane. This paper discusses in detail the implementation of VPH concept that intent to eliminate the degraded type failures in the data plane and its advantages. Also this evaluates a more efficient, non-periodic VPH concept. The results of the computer simulations show VPH is a proactive technique to eliminate degraded type failures and improve the availability of the networks.

Virtual path hopping to overcome network failures due to control plane failures in connection oriented networks

Real time traffic is a predominant traffic type in the next generation communication IP networks and the future applications demand for 100% reliability and availability of networks. The guarantees of QoS expected can be achieved by connection oriented networks such as MPLS. The control plane and the data plane of MPLS are logically separated Therefore any failures in the control plane not necessarily should affect the communication sessions in the data plane. Label distribution protocol (LDP) which is preferred over RSVP as a control plane protocol in MPLS, uses TCP in the transport layer for most of its message transmissions. TCP resets all the participating peers, at any terminations of LDP sessions, leading the applications to terminate the corresponding data plane communications. If the keep alive timers of the LDP peers expire without receiving protocol data units (PDU) from the neighboring peers, it terminates the LDP session resulting in a network failure due to control plane failure. None of the existing restoration schemes distinguish this type of control plane failures from the normal data plane path/link failures. It is found that about 50% of the network failures are of this type and if they can be avoided without disturbing the data plane, it will improve the availability and the reliability of the connection oriented networks drastically. A novel idea of virtual path hopping (VPH) is proposed, which can avoid all the control plane failures from affecting the communications in the data plane. The computer simulations performed, prove that it is possible to avoid about 50% re-routings due to failures in the data plane and this explains that the control plane failures are looked after by the VPH concept.

A connection-oriented network architecture with guaranteed QoS for future real-time applications over the internet

The QoS provided by todays best effort Internet is not good enough, especially for real-time interactive traffic categorized as Premium Traffic (PT). It is believed that QoS guarantees could be better provided by connection-oriented networks such as IP/MPLS. However, these connection-oriented networks are inherently more prone to network failures. Failures of connection-oriented MPLS can be broadly classified into two types namely: link/path failures and degraded failures. Degraded failures that account for about 50% of total failures are detected by the timers maintained at the control plane peers. The control plane and the data plane of IP/MPLS packet networks are logically separated and therefore a failure in the control plane should not immediately disconnect the communications in the data plane. The Virtual Path Hopping (VPH) concept in this study distinguishes these two types of failures and avoids the disconnections of communications in the data plane due to degraded failures. Thereby it reduces the number of failures in the data plane. Computer simulations were performed and the results indicate that VPH is a proactive technique that minimizes failures in the dala plane. The proposed Dynamic Virtual Path Allocation (DVPA) algorithm improves the availability of the connection-oriented networks by overcoming link/path failures, especially for PT, without compromising the network resource utilization efficiency. Comprehensive simulations were performed to evaluate the DVPA algorithm and the results show the improvements that DVPA can achieve. Therefore implementation of the DVPA algorithm in conjunction with VPH would improve the reliability and availability aspects of QoS in connection-oriented IP/MPLS packet networks.

Cell loss recovery using adaptive LDPC-based FEC method for real time services over best effort networks

Real-time services over best-effort networks, such as teleconferencing over unspecified bit rate (UBR) class asynchronous transfer mode (ATM) networks or the Internet, have a very high demand as they are cost effective. However, cell loss caused by buffer overflow at switches is a serious problem in this service class, and is responsible for degradation of the quality of service (QoS). Forward error correction (FEC) is a promising technology for recovering lost cells and improving the QoS of best-effort networks. Conventional FEC methods utilize a FEC matrix with fixed dimensions and are usually designed to cope with the worst case of cell losses. A new method that provides dynamic recovery capacity to deal with the current cell loss ratio through the use of a variable-dimension FEC matrix is proposed. The scheme also takes into account the coding method of the FEC matrix. Numerical results show that the cell loss ratio and transmission efficiency of the proposed method are superior to those of conventional methods.