Wyniki wyszukiwania - BazTech

1

Alternative route search algorithm for robust and balanced traffic in telecommunication network

Wiktor M.

Computational Methods in Science and Technology

|

2019

|

Vol. 25, No. 1

7--15

EN

This paper discusses routing policy in optical transport networks. Dijkstra’s shortest path algorithm is compared to a new path computation technique based on heuristics originated from human behavior combined with spectral graph embedding. The two-step procedure allows one to separate the computationally expensive and computationally cheap parts for efficient implementation in network infrastructure.

2

Service restoration in survivable networks under attacks

Gierszewski T., Molisz W., Rak J.

Systems Science

|

2006

|

Vol. 32, no 3

15-26

EN

A comparison of service restoration quality in survivable optical transport networks OTN (WDM) degraded due to physical failures or degraded after intentional attack is described. Survivability assumptions are as follows: end-to-end path protection: preplanned node-disjoint backup path for each working path. The lightpaths optimization problem in survivable networks is NP-complete and we propose the heuristic SCNDP algorithm to solve the problem. The original author’s network simulator was used to model five network: National Science Foundation (NSF) network, PIONIER (Polish Optical Internet). Italian optical network, artificial intermediate network (AIN) and artificial scale-free network (ASF), corresponding to parameters of NSF. Single node outages being either a consequence of physical failures, or resulting from malicious attacks were simulated in each of the five networks. We showed that the differences in the effectiveness of service restoration caused by these two mechanisms are rather small in networks having regular topologies (like NSF), but in contrast, are significant in intermediate and scale-free networks (much more vulnerable to attacks). All results are the original contribution and are published for the first time.

3

Survivability issues in IP-MPLS networks

Molisz W.

Systems Science

|

2005

|

Vol. 31, no 4

87-107

EN

A model for survivability assessment of IP-MPLS networks implemented directly in optical transport networks OTN (WDM) is described under assumptions as follows: end-to-end path protection; preplanned node-disjoint, dedicated or shared, backup path for each working path: distributed control of all top-down restoration actions: LSP-to-lightpath mapping minimizing the number of wavelengths converters. Survivability of such networks has a fundamental importance, since a single link cut can affect extremely large traffic volumes. The optimization problem ofsurvivable routing and wavelength assignment (SRWA) can be decomposed into a survivable routing followed by a wavelength assignment optimization problem. They are stated as the mixed integer and integer programming problems, respectively. Unfortunately, they both are NP-complete. Heuristic algorithms are proposed to solve the problems. The presented approach has been verified by means of simulation. Some results of the large number of simulation experiments investigating networks: DARPA. and NSF are described and discussed. Conclusions help in better understanding of survivability issues in IP-MPLS networks. All results are the original contribution and are published for the first time.

4

Survivability issues in IP-MPLS networks

Molisz W.

Systems Science

|

2005

|

Vol. 31, no 2

97-105

EN

A model for survivability assessment of IP-MPLS networks implemented directly in optical transport networks OTN (WDM) is described under assumptions as follows: end-to-end path protection; preplanned node-disjoint, dedicated or shared, backup path for each working path; distributed control of all top-down restoration actions; LSP-to-lightpath mapping minimizing the number of wavelength converters. Survivability of such networks has a fundamental importance, since a single link cut can affect extremely large traffic volumes. The optimization problem of survivable routing and wavelength assignment (SRWA) can be decomposed into a survivable routing followed by a wavelength assignment optimization problem. They are stated as the mixed integer and integer programming problems, respectively. Unfortunately, they both are NP-complete. Heuristic algorithms are proposed to solve the problems. The presented approach has been verified by means of simulation. Some results of the large number of simulation experiments investigating networks: DARPA, and NSF are described and discussed. Conclusions help in better understanding of survivability issues in IP-MPLS networks. All results are the original contribution and are published for the first time.

5

Wymagania funkcjonalne dla optycznych sieci transportowych OTN (Optical Transport Network)

Lasoń A.

Telekomunikacja Cyfrowa : technologie i usługi

|

2000

|

T. 3, z. 2

108-115

PL

W artykule przedstawiono propozycje wymagań funkcjonalnych dla optycznych sieci transportowych nowej generacji. Na wstępie omówiono aktualne kierunki zmian zachodzących na rynku usług telekomunikacyjnych. Szczególną uwagę poświęcono usługom transportowym - usługom świadczonym na poziomie warstwy optycznej, warstwy SDH oraz IP. Wymagania funkcjonalne dla przyszłych sieci transportowych określone zostały przy założeniu warstwowej architektury IP/OTN, jako architektury docelowej. Artykuł podsumowany został wskazaniem możliwych kierunków rozwoju optycznych sieci transportowych.

EN

The paper discussed functional requirements for new generation optical transport networks. The most important trends in development of the telecommunication services are presented as an introduction. Special attention is paid to the transport services, services available at the optical, SDH or IP layer. Functional requirements have been defined assuming the IP/OTN architecture of the future transport networks. The paper is summarized with indication of the most likely trends in the evolution of the transport networks.