The results of Offline Inter-domain TE can be divided into three areas.

In the first area, we have applied an evolutionary Genetic Algorithm (GA) to solve offline traffic engineering problems that are based on the MESCAL QoS model. Our model works on a traffic matrix that includes delay and bandwidth as QoS parameters. The algorithm finds near-optimum assignments of traffic matrix aggregate flows to intra-domain resources (represented by an l-QC) and inter-domain resources (represented by a pSLS, that is, an o-QC offered by a downstream domain) in such a way as to minimise the total cost to the domain’s INP.

We have compared the GA with a random assignment algorithm (effectively representing current day best-effort inter-domain traffic engineering practices applied to a QoS-aware environment), and a brute force assignment algorithm. We have shown that in a simplified validation scenario the genetic algorithm obtains results that are close to an analytically obtainable lower bound solution. We have also demonstrated that in more complex scenarios the GA can be used to obtain offline QoS-aware traffic engineering solutions that are of significantly lower cost than a random approach.

In our second area, we have developed three heuristic algorithms to solve the integrated inter-domain / intra-domain TE problem for a traffic matrix in which bandwidth is used as the QoS parameter. Simulation results show that the Greedy-penalty performs better than the other two algorithms in terms of total network bandwidth consumption.

In the third area, we have explored the relationship between intra-domain and inter-domain TE, and explored the interaction between them by proposing and analyzing both a decoupled and integrated approach. We have shown through simulation how the integrated approach results in lower cost TE solutions with lower total consumed bandwidth than the decoupled approach.

Further reading:

M.P. Howarth, M. Boucadair, P. Flegkas, N. Wang, G. Pavlou, P. Morand, T. Coadic, D. Griffin, A. Asgari and P. Georgatsos, "End-to-end quality of service provisioning through Inter-provider traffic engineering," to appear in Computer Communications, Elsevier, end 2005.

K.H.Ho, M. Howarth, N. Wang, G. Pavlou and S. Georgoulas, "Two Approaches to Internet Traffic Engineering for End-to-end Quality of Service Provisioning,"  poster in Proc. 1st EuroNGI Conference on Next Generation Internet Networks - Traffic Engineering, Rome, Italy, 18-20 April 2005. [link]

K. Ho, N. Wang, P. Trimintzios, G. Pavlou, M.P. Howarth, "On Egress Router Selection for Inter-domain Traffic with Bandwidth Guarantees," Proc. IEEE Workshop in High Performance Switching and Routing (HPSR'2004), Phoenix, Arizona, USA, IEEE, 18-21 April 2004. [link]

MESCAL deliverable D1.3, "Final specification of protocols and algorithms for inter-domain SLS management and traffic engineering for QoS-based IP service delivery", Chapter 10, section 10.4. [link]

MESCAL deliverable D3.2, "Final experimental results: validation and performance assessment of algorithms and protocols for inter-domain QoS through service-driven traffic engineering", Chapter 3, section 3.1. [link]