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UB CSE 620 - Introduction to Protection and Restoration for OBS

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Introduction to Protection & Restoration for OBSOutlineBasic Concepts of Protection & RestorationWhat is protection & Restoration?Why we need Protection/Restoration?ProtectionPath ProtectionPath Protection (Continued)Dedicated Path Protection1+1 ProtectionMesh Network ProtectionShared Path Protection1:1 Protection1:N ProtectionLink ProtectionLink Protection (Continued)Dedicated Link ProtectionAdvantages & Disadvantages of ProtectionRestorationPath RestorationLink RestorationAdvantages & Disadvantages of RestorationComparison between Protection & RestorationComparison between Protection & Restoration (Continued)Protection/Restoration for Optical NetworkWavelength Path (WP) & Virtual Wavelength Path (VWP)WP & VWP (Continued)Review of OBSMain Advantages of OBSMain Advantages of OBS (Continued)Requirement & AssumptionRequirement & Assumption (Continued)Protection & Restoration for OBSProtection/Restoration At The Source NodeProtection/Restoration At Intermediate NodeProtection/Restoration At Intermediate Node (Continued)MPLS ProtectionOverview of MPLS ProtectionMotivation for MPLS ProtectionMPLS Protection PrinciplesObjectives of MPLS ProtectionObjectives of MPLS Protection (Cont’)Protection ConfigurationProtection ActivationProtection SpanProtection ModesProtection Switching OptionsFailure DetectionAn MPLS path recovery mechanismCore MPLS Path Protection ComponentsReverse Notification Tree (RNT)Illustration of MPLS protection configurationProtection DomainRelationship between protection domainsMultiple FaultsConfigurationEstablishing a Recovery/Protection PathFault DetectionFault ProcessingDomains With different RNTs (Independent)Domains With different RNTs (Overlap)Domains With same RNTGraph of Switch OverInverse cross-connect tableReferenceReference (Cont’)Introduction to Protection & Restoration for OBS Copyright, 2000, SUNY, Univ. at BuffaloPresented by Zaoyang Guo & Dahai XuOutline• Basic Concepts of Protection & Restoration• Review of OBS• Protection & Restoration for OBSBasic Concepts of Protection & Restoration• What is protection & Restoration?• Why we need Protection/Restoration?• Protection• Restoration• Comparison between Protection & Restoration• Protection/Restoration for Optical NetworkWhat is protection & Restoration?• Network is unreliable somehow• Protection & Restoration are the mechanisms to recover from network failure• Their difference will be discussed in the following partsWhy we need Protection/Restoration?• To Recover from network failure• To prevent a lot of data loss• To provide reliable communication serviceProtection• Path Protection• Link Protection• Advantages & DisadvantagesPath Protection• Use more than one path to guarantee the data be sent successfullyPath Protection (Continued)• Dedicated Path Protection• Shared Path ProtectionDedicated Path Protection• 1+1 Protection• Point-to-Point Protection & Mesh Network Protection1+1 ProtectionMesh Network ProtectionShared Path Protection• 1:1 Protection• 1:N Protection1:1 Protection1:N ProtectionLink Protection• Use an alternate path if the link failedLink Protection (Continued)• Dedicated Link Protection: not practical• Shared Link Protection: practical • It may fail when a node failsDedicated Link ProtectionAdvantages & Disadvantages of Protection• Simple• Quick: Do not require much extra process time• Usually can only recover from single link fault• Inefficient usage of resourceRestoration• Path Restoration• Link Restoration• Advantages & DisadvantagesPath Restoration• The route can be computed after failure• The resource is reserved and then usedLink Restoration• The path is discovered at the end nodes of the failed link• More practical than path restorationAdvantages & Disadvantages of Restoration• Usually can recover from multiplex element faults• More efficient usage of resource• Complex• Slow: require extra process time to setup path and reserve resource•Characteristic: Protection -- the resource are reserved before the failure, they may be not used; Restoration -- the resource are reserved and used after the failure•route: Protection -- predetermined; Restoration -- can be dynamically computed•Resource Efficiency: Protection -- Low; Restoration -- HighComparison between Protection & Restoration•Time used: Protection -- Short; Restoration -- Long•Reliability: Protection -- mainly for single fault; Restoration -- can survive under multiplex faults•Implementation: Protection -- Simple; Restoration -- ComplexComparison between Protection & Restoration (Continued)Protection/Restoration for Optical Network • Wavelength Path (WP) & Virtual Wavelength Path (VWP)• FDL: to delay data• Routing: central controlled or distributed controlled•Resource Reservation: forward reservation / backward reservationWavelength Path (WP) & Virtual Wavelength Path (VWP)• Wavelength Path (WP) / Lightpath (LP) : a wavelength and a physical path, no wavelength translation is used• Virtual Wavelength Path (VWP) : wavelength translation may be employed• Optical cross-connectionWP & VWP (Continued)• Three types of network: no wavelength translation at all nodes; wavelength translation at all nodes; wavelength translation at some nodesReview of OBS• Main Advantages of OBS• Requirement & AssumptionMain Advantages of OBS• •No buffer capacity is required at intermediate nodes: A lightpath/wavelength Path (WP) or Virtual Wavelength Path (VWP) must be setup• Quick Setup: No acknowledgement from receiver (destination)Main Advantages of OBS (Continued)• Low Overhead: A control packet is sent and processed before the busty data transmission• High efficient utilization of bandwidth: No acknowledgement from destination, low overheadRequirement & Assumption• Reliable Network: No ack.• OBS is mainly used in backbone networks• Every node knows sufficient information about the route or the topology of the whole networkRequirement & Assumption (Continued)•If one element in the network fails, all the nodes will be notified in a short time• Assume there will be only one element fail: If one element fails, the others will work correctly • Generally only single link failure is consideredProtection & Restoration for OBS• Protection/Restoration At The Source Node• Protection/Restoration At Intermediate NodeProtection/Restoration At The Source Node• Dedicated Path Protection: Send burst data to each


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