# US 11,121,964 B2 · Data path retention during control plane failures in a multiprotocol label switching network > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,121,964 B2 - Document ID: US11121964B2 - Status: Granted - Kind: B2 - Application number: 16/159,845 - Filed: 2018-10-15 - Published: 2020-03-05 - Granted: 2021-09-14 - Earliest claimed: 2018-08-31 - Assignees: Ciena Corporation - Applicants: Ciena Corporation - Inventors: Deepak Seth; Rahul Kumar Barche; Bhartendu Maheshwari; Jasnam Singh - Web page: https://patentgrep.com/patent/US11121964B2 ## CPC - H04L 45/28: using route fault recovery - H04L 41/0663: Performing the actions predefined by failover planning, e.g. switching to standby network elements - H04L 43/0811: by checking connectivity - H04L 43/10: Active monitoring, e.g. heartbeat, ping or trace-route - H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS] - H04L 47/746: {Reaction triggered by a failure} - H04L 45/64: using an overlay routing layer - H04L 49/70: {Virtual switches} - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Systems and methods for data path retention during control plane failures in a Multiprotocol Label Switching (MPLS) network include, in a network element, operating an MPLS service on a data path in the MPLS network in an initial stage with both a control plane and a data plane operating normally; responsive to a failure affecting only the control plane, switching the MPLS service to an Ethernet Line (ELINE) service which is configured on the data path; and, responsive to a recovery of the control plane, switching the ELINE service back to the MPLS service. ## Claims ### Claim 1 A method for data path retention during control plane failures in a Multiprotocol Label Switching (MPLS) network, the method comprising: in a network element, operating an MPLS service on a data path in the MPLS network in an initial stage with both a control plane and a data plane operating normally; responsive to a failure affecting only the control plane where the data plane remains operational, switching the MPLS service to an Ethernet Line (ELINE) service which is configured on the data path that is a same path as the MPLS service, the ELINE service being pre-configured to protect a tunnel of the MPLS service over the same path, wherein the MPLS service and the ELINE service are both connected to a Virtual Switch (VS) and associated ports of the VS are blocked and unblocked utilizing Virtual Link Loss Indication (VLLI) and inverse VLLI (iVLLI) based on a state of the control plane; and responsive to a recovery of the control plane, switching the ELINE service back to the MPLS service. ### Claim 2 (depends on 1) The method of claim 1, wherein a Connectivity Fault Management (CFM) UP Maintenance End Point (MEP) is configured between a port of the network element and an associated port of an egress network element at an opposite end of the data path. ### Claim 3 (depends on 2) The method of claim 2, wherein the network element is configured to detect the failure based on Continuity Check Messages (CCMs) received on the CFM UP MEP. ### Claim 4 (depends on 3) The method of claim 3, wherein the CCMs are blocked on the ELINE service, utilizing an Access flow, responsive to the failure. ### Claim 5 (depends on 1) The method of claim 1, wherein the MPLS service is one of an unprotected static tunnel and a sticky co-routed tunnel, over the data path which is a Label Switched Path (LSP). ### Claim 6 (depends on 1) The method of claim 1, wherein the failure is due to any of Media Access Control (MAC) resolution using Address Resolution Protocol (ARP); a routing protocol convergence/failure in one of Intermediate System-Intermediate System (ISIS) and Open Shortest Path First (OSPF); an Operations, Administration, and Maintenance (OAM) Bidirectional Fault Detection (BFD) failure; a tunnel signaling message failure in one of Resource Reservation Protocol (RSVP) and Constraint-based Routing Label Distribution Protocol (CR-LDP); and a Pseudowire (PW) signaling message failure. ### Claim 7 A network element configured for data path retention during control plane failures in a Multiprotocol Label Switching (MPLS) network, the network element comprising: one or more line modules with associated ports; a switching fabric interconnecting the associated ports; and a controller communicatively coupled to the one or more line modules and the switching fabric, wherein the controller is configured to: operate an MPLS service on a data path via a port of the associated ports connected to the MPLS network in an initial stage with both a control plane and a data plane operating normally, responsive to a failure affecting only the control plane where the data plane remains operational, switch the MPLS service to an Ethernet Line (ELINE) service which is configured on the data path that is a same path as the MPLS service, the ELINE service being pre-configured to protect a tunnel of the MPLS service over the same path, wherein the MPLS service and the ELINE service are both connected to a Virtual Switch (VS) and associated ports of the VS are blocked and unblocked utilizing Virtual Link Loss Indication (VLLI) and inverse VLLI (iVLLI) based on a state of the control plane, and responsive to a recovery of the control plane, switch the ELINE service back to the MPLS service. ### Claim 8 (depends on 7) The network element of claim 7, wherein a Connectivity Fault Management (CFM) UP Maintenance End Point (MEP) is configured between a port of the network element and an associated port of an egress network element at an opposite end of the data path. ### Claim 9 (depends on 8) The network element of claim 8, wherein the network element is configured to detect the failure based on Continuity Check Messages (CCMs) received on the CFM UP MEP. ### Claim 10 (depends on 9) The network element of claim 9, wherein the CCMs are blocked on the ELINE service, utilizing an Access flow, responsive to the failure. ### Claim 11 (depends on 7) The network element of claim 7, wherein the MPLS service is one of an unprotected static tunnel and a sticky co-routed tunnel, over the data path which is a Label Switched Path (LSP). ### Claim 12 (depends on 7) The network element of claim 7, wherein the failure is due to any of Media Access Control (MAC) resolution using Address Resolution Protocol (ARP); a routing protocol convergence/failure in one of Intermediate System-Intermediate System (ISIS) and Open Shortest Path First (OSPF); an Operations, Administration, and Maintenance (OAM) Bidirectional Fault Detection (BFD) failure; a tunnel signaling message failure in one of Resource Reservation Protocol (RSVP) and Constraint-based Routing Label Distribution Protocol (CR-LDP); and a Pseudowire (PW) signaling message failure. ### Claim 13 A Multiprotocol Label Switching (MPLS) network configured for data path retention during control plane failure, the MPLS network comprising: a plurality of physical network elements interconnected to one another, including a data path; and an MPLS service, wherein the MPLS service is configured between two Label Edge Routers (LERs) of the plurality of physical network elements via the data path and the MPLS service is in an initial stage with both a control plane and a data plane operating normally, wherein, responsive to a failure affecting only the control plane where the data plane remains operational, the MPLS service is switched to an Ethernet Line (ELINE) service which is configured on the data path that is a same path as the MPLS service, the ELINE service being pre-configured to protect a tunnel of the MPLS service over the same path wherein the MPLS service and the ELINE service are both connected to a Virtual Switch (VS) and associated ports of the VS are blocked and unblocked utilizing Virtual Link Loss Indication (VLLI) and inverse VLLI (iVLLI) based on a state of the control plane, and wherein, responsive to a recovery of the control plane, the ELINE service is switched back to the MPLS service. ### Claim 14 (depends on 13) The MPLS network of claim 13, wherein a Connectivity Fault Management (CFM) UP Maintenance End Point (MEP) is configured between a port of a network element of the plurality of physical network elements and an associated port of an egress network element at an opposite end of the data path. ### Claim 15 (depends on 14) The MPLS network of claim 14, wherein the network element is configured to detect the failure based on Continuity Check Messages (CCMs) received on the CFM UP MEP. ### Claim 16 (depends on 15) The MPLS network of claim 15, wherein the CCMs are blocked on the ELINE service, utilizing an Access flow, responsive to the failure. ### Claim 17 (depends on 13) The MPLS network of claim 13, wherein the MPLS service is one of an unprotected static tunnel and a sticky co-routed tunnel, over the data path which is a Label Switched Path (LSP).