Research Publications (Engineering and Built Environment)
Permanent URI for this collectionhttp://ir-dev.dut.ac.za/handle/10321/215
Browse
3 results
Search Results
Item A routing and wavelength assignment (RWA) scheme for deflected bursts in optical burst switched networks(Turkish Online Journal of Qualitative Inquiry (TOJQI), 2021-11-01) Nleya, Bakhe; Gomba, MasimbaAll Optical Burst Switched (OBS transport networks are often characterized by frequent occurrences of both contention and wavelength congestion. Their occurring often leads to degradations in overall network performance in handling moderate to high traffic levels, and all this leading to increases in data burst losses. Deflection routing contention resolution is quite popular in combating both types of congestions and ultimately leading to improvements in overall network throughput. However, it is necessary that network throughput always balance with effective utilization. In this paper, we propose a prioritized (indexed) cooperative based routing and wavelength assignment (PIC-RWA) scheme that reduce both contention and wavelength congestions. Performance results indicate that it significantly improves overall network performance in terms of improved effective resources utilizationItem A RWA framework for improved throughput in OBS networks(Springer Science and Business Media LLC, 2021-08) Nleya, BakheAll-Optical Burst Switched (OBS) backbone transport networks facilitate connectionless transport utilizing wavelength division multiplexing of multiple lightpaths end-to-end channels. The data in such networks is transmitted in the form of bursts. However, whereas such networks provide capacities in the Terahertz ranges, the data bursts being ferried often contend with each other at intermediate (interior) buffer-less nodes. The frequent occurrences of both contentions, as well as wavelength congestions, are often characterized by degradations in overall network performance in handling moderate to high traffic levels, and all this is attributed to increases in burst losses. Whereas deflection routing contention resolution is quite popular in combating both contention and wavelength congestions to improve overall network throughput, it is however necessary that network throughput always balances with effective utilization. Further complexity is that of most practical backbone transport networks often being multi-domain in nature and thus necessitating the dimensioning of deflection routing resources for both interdomain and intra-domain traffic to avoid degradation of network performance in terms of contention as well as wavelength congestion occurrences in one domain due to improper dimensioning in the other(s). In this regard, a combination of appropriately designating border nodes and grooming interdomain traffic will vastly improve overall network performance as well as fairness to multiple domain lightpath connections. In this paper, we propose a prioritized (indexed) cooperativebased routing and wavelength assignment (PIC-RWA) scheme that couples with wavelength grooming for inter-border traffic to reduce both contention and wavelength congestions. Performance results indicate that it significantly improves overall network performance in terms of improved effective resources utilization.Item A controlled deflection routing and wavelength assignment based scheme in Optical Burst Switched (OBS) networks(Walter de Gruyter GmbH, 2020-07-05) Nleya, Bakhe; Khumalo, Zephaniah Philani; Mutsvangwa, AndrewAbstract - Heterogeneous IoT-enabled networks generally accommodate both jitter tolerant and intolerant traffic. Optical Burst Switched (OBS) backbone networks handle the resultant volumes of such traffic by transmitting it in huge size chunks called bursts. Because of the lack of or limited buffering capabilities within the core network, burst contentions may frequently occur and thus affect overall supportable quality of service (QoS). Burst contention(s) in the core network is generally characterized by frequent burst losses as well as differential delays especially when traffic levels surge. Burst contention can be resolved in the core network by way of partial buffering using fiber delay lines (FDLs), wavelength conversion using wavelength converters (WCs) or deflection routing. In this paper, we assume that burst contention is resolved by way of deflecting contending bursts to other less congested paths even though this may lead to differential delays incurred by bursts as they traverse the network. This will contribute to undesirable jitter that may ultimately compromise overall QoS. Noting that jitter is mostly caused by deflection routing which itself is a result of poor wavelength and routing assigning, the paper proposes a controlled deflection routing (CDR) and wavelength assignment based scheme that allows the deflection of bursts to alternate paths only after controller buffer preset thresholds are surpassed. In this way, bursts (or burst fragments) intended for a common destination are always most likely to be routed on the same or least cost path end-to-end. We describe the scheme as well as compare its performance to other existing approaches. Overall, both analytical and simulation results show that the proposed scheme does lower both congestion (on deflection routes) as well as jitter, thus also improving throughput as well as avoiding congestion on deflection paths.