scholarly journals Reliable Routings in Networks with Generalized Link Failure Events

2011 ◽  
pp. 76-79
Author(s):  
Shailesh Kumar ◽  
Dr. M. SIDDAPPA
Keyword(s):  
Link Failure ◽  
Switched Networks ◽  
Link Failures ◽  
Backup Path ◽  
Link Group ◽  
Network Link ◽  
Single Link ◽  
Failure Event ◽  
Shared Risk ◽  
Multiple Link Failures

Traditional methods for ensuring reliable transmissions in circuit- switched networks rely on the pre computation of a backup path for every working path or for every network link These methods work fine as long as the network experiences only single link failures. They do not guarantee undisturbed communication, however, in the case of multiple link failures. Such failures are not seldom and often are correlated: a single failure in the physical network (a cut in the conduit carrying wiring or fibers used for several links) results in several failures in the abstract network layer (see for a discussion on multiple link failures). This type of link failures can be modeled using the notion of generalized failure events. A single generalized failure leads to the failure of several links in the network. Links that belong to the same failure even are also said to be in the same shared risk link group. Recent research has focused on the problem of computing, for a given pair of nodes, two risk-disjoint paths, i.e., two paths that do not share links that belong to the same generalized failure event.

Software-Defined Networking Switches for Fast Single-Link Failure Recovery

2018 ◽  
Vol 18 (04) ◽  
pp. 1850014
Author(s):  
DAWEI LI ◽  
JIE WU ◽  
DAJIN WANG ◽  
JIAYIN WANG
Keyword(s):  
Network Topology ◽  
Routing Protocols ◽  
Shortest Paths ◽  
Software Defined Networking ◽  
Failure Recovery ◽  
Link Failure ◽  
Fast Recovery ◽  
Link Failures ◽  
Single Link

In this paper, we consider IP fast recovery from single-link failures in a given network topology. The basic idea is to replace some existing routers with a designated switch. When a link fails, the affected router will send all the affected traffic to the designated switch (through pre-configured IP tunnels), which will deliver the affected traffic to its destination without using the failed link. The goal of the approach is to achieve faster failure recovery than traditional routing protocols that employ reactive computing upon link failures. Software-Defined Networking (SDN) switches can serve as the designated switches because they can flexibly redirect affected traffic to other routes, instead of only to the shortest paths in the network. However, SDN switches are very expensive. Our objective is to minimize the number of SDN switches needed and to guarantee that the network can still recover from any single-link failure. For networks with uniform link costs, we show that using normal non-SDN switches with IP tunneling capability as designated switches can guarantee recovery from any single-link failure. For networks with general link costs, we find that not all single-link failures can be recovered by using non-SDN switches as designated switches; by using SDN switches only when necessary, we can reduce the total number of SDN switches needed compared to an existing work. We conduct extensive simulations to verify our proposed approaches.

Protection Survivability Architectures

2011 ◽  
pp. 27-56
Author(s):  
Péter Babarczi ◽  
János Tapolcai
Keyword(s):  
Wavelength Division Multiplexing ◽  
Link Failures ◽  
Wavelength Division ◽  
Backbone Networks ◽  
High Data ◽  
Link Group ◽  
Data Rates ◽  
Application Data ◽  
End To End ◽  
Shared Risk

Survivable routing serves as one of the most important issues in optical backbone design. Due to the high data rates enabled by the wavelength division multiplexing technology, any interruption in the service results in the loss of a large amount of application data. Thus, making efforts to calculate and signal the protection resources promptly after the failure occurred would lead to an unacceptable high delay. As the main purpose of this chapter, the principles of pre-planned protection approaches in mesh optical backbone networks are discussed. The Shared Risk Link Group (SRLG) concept is introduced modeling physical and geographical dependency among seemingly unrelated link failures. Finally, methods are presented for calculating the exact end-to-end availability of a connection.

Link Failure Recovery in SDN: High Efficiency, Strong Scalability and Wide Applicability

2018 ◽  
Vol 27 (06) ◽  
pp. 1850087 ◽  
Author(s):  
Jue Chen ◽  
Jinbang Chen ◽  
Junchen Ling ◽  
Junlong Zhou ◽  
Wei Zhang
Keyword(s):  
High Efficiency ◽  
Failure Recovery ◽  
Link Failure ◽  
Protection Mechanism ◽  
Link Failures ◽  
Wide Applicability ◽  
Backup Path ◽  
Protection Method ◽  
Network Scale ◽  
Backup Paths

Link failures are commonly observed in computer networks, including the newly emerging Software Defined Network (SDN). Considering that failure recovery methods used in traditional networks cannot be applied to SDN networks directly, we propose a method named pro-VLAN in this paper, which calculates a backup path and assigns a unique VLAN id for each link of the network based on the protection mechanism. It makes the most of SDN’s features and can recover a single link failure in SDN with the advantages of high efficiency, strong scalability and wide applicability. More specifically, high efficiency (i.e., a fast failure recovery with a low memory consumption) is achieved by calculating backup paths for each link instead of each flow and using group tables to switch backup paths automatically and locally when failures occur. Strong scalability (i.e., the amount of backup flow entries per switch is stable) is achieved by keeping the amount of links per switch no matter how the network scale extends or how the amount of flows increases. Wide applicability is achieved by always finding a path available without modifying any hardware or protocol as long as the network is still reachable after a link failure. Simulation results and mathematical analysis demonstrate that both pro-VLAN and a flow-based protection method achieve a fast failure recovery, while pro-VLAN consumes less than 1% of the forwarding entries to store backup paths as compared to the flow-based method. Moreover, when the network scale increases from 10 to 60 switches by 500%, the increase of the number of backup flow entries per switch built by pro-VLAN is only less than 50%.

On Number of Planes of Rearrangeably Nonblocking Optical Banyan Networks with Link Failures

2008 ◽  
Vol 1 (1) ◽  
pp. 43-54
Author(s):  
Basra Sultana ◽  
Mamun-ur-Rashid Khandker
Keyword(s):  
Optical Switching ◽  
Blocking Probability ◽  
Link Failure ◽  
Link Failures ◽  
Small Depth ◽  
Internal Link ◽  
Banyan Network ◽  
Minimum Number ◽  
Switch Design ◽  
Banyan Networks

Vertically stacked optical banyan (VSOB) networks are attractive for serving as optical switching systems due to the desirable properties (such as the small depth and self-routing capability) of banyan network structures. Although banyan-type networks result in severe blocking and crosstalk, both these problems can be minimized by using sufficient number of banyan planes in the VSOB network structure. The number of banyan planes is minimum for rearrangeably nonblocking and maximum for strictly nonblocking structure. Both results are available for VSOB networks when there exist no internal link-failures. Since the issue of link-failure is unavoidable, we intend to find the minimum number of planes required to make a VSOB network nonblocking when some links are broken or failed in the structure. This paper presents the approximate number of planes required to make a VSOB networks rearrangeably nonblocking allowing link-failures. We also show an interesting behavior of the  blocking  probability of a faulty VSOB networks that the blocking probability may not  always  increase monotonously with  the  increase  of  link-failures; blocking probability  decreases  for  certain range of  link-failures, and then increases again. We believe that such fluctuating behavior of blocking probability with the increase of link failure probability deserves special attention in switch design.  Keywords: Banyan networks; Blocking probability; Switching networks; Vertical stacking; Link-failures. © 2009 JSR Publications. ISSN: 2070-0237(Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v1i1.1070

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