# US 2017/0288948 A1 · Failure handling for active-standby redundancy in evpn data center interconnect > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0288948 A1 - Document ID: US20170288948A1 - Status: Published application - Kind: A1 - Application number: 15/085,533 - Filed: 2016-03-30 - Published: 2017-10-05 - Earliest claimed: 2016-03-30 - Assignees: Juniper Networks, Inc. - Applicants: Juniper Networks, Inc. - Inventors: Tapraj Singh; Wen Lin; SelvaKumar Sivaraj; Rukesh Dorai; Sunesh Rustagi - Web page: https://patentgrep.com/patent/US20170288948A1 ## CPC - H04L 45/28: using route fault recovery - H04L 12/4633: {Interconnection of networks using encapsulation techniques, e.g. tunneling} - H04L 41/0659: by isolating or reconfiguring faulty entities - H04L 41/0668: by dynamic selection of recovery network elements, e.g. replacement by the most appropriate element after failure - H04L 43/0811: by checking connectivity - H04L 45/247: using M:N active or standby paths - H04L 45/50: using label swapping, e.g. multi-protocol label switch [MPLS] - H04L 45/66: {Layer 2 routing, e.g. in Ethernet based MAN's} - H04L 45/74: Address processing for routing - H04L 43/0817: by checking functioning - H04L 43/10: Active monitoring, e.g. heartbeat, ping or trace-route - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract Techniques are described for avoiding traffic black-holing in a multi-homed Ethernet virtual private networks (EVPNs) in which a customer device (CE) is multi-homed to a plurality of multi-homing provider edge devices (PEs) via respective links of an Ethernet segment. An overlay network is created over the Ethernet segment, and the multi-homing PEs of the EVPN are configured with a common anycast IP address for respective virtual network interfaces. Upon election as active designated forwarder (DF) for the EVPN, the DF PE of the multi-homing PEs advertises toward the customer network an IGP metric for the anycast IP address that is lower than the IGP metric(s) advertised by any of the non-DF standby PE routers segment to direct the CE to forward network packets from the customer network to the DF PE over the respective link of the Ethernet segment. ## Claims ### Claim 1 A method comprising: executing, with a provider edge device (PE) of a plurality of PEs coupled to a multi-homed customer edge device (CE) by an overlay network formed over an active-standby multi-link Ethernet segment, an Ethernet Virtual Private Network (EVPN) instance to provide an EVPN over an intermediate network to one or more remote provide edge devices; participating, with the PE device, in a designated forwarder (DF) election of one of the PEs for forwarding packets from the EVPN to the customer network by the Ethernet segment; and responsive to the PE being elected the DF, outputting, with the PE according to an interior gateway protocol (IGP) routing protocol, an IGP message specifying a metric for reaching a virtual network interface of the PE for the overlay network by a respective link of the Ethernet segment to direct the CE to forward network packets from the customer network to the PE. ### Claim 2 (depends on 1) The method of claim 1, further comprising, responsive to a different one of the PEs subsequently being elected the DF for the EVPN, outputting, with the PE, a second IGP message to modify the metric to indicate a longer routing distance for reaching the virtual network interface of the PE via the respective link of the Ethernet segment to direct the CE to forward subsequent network packets from the customer network to the different one of the PEs. ### Claim 3 (depends on 2) The method of claim 2, wherein the metric of the IGP message output when the PE is elected DF comprises a MIN_IGP metric having a minimum permissible value for the IGP routing protocol, and wherein the metric of the second IGP message when a different one of the PEs is elected the DF comprises a MAX_IGP metric having a maximum permissible value for the IGP routing protocol. ### Claim 4 (depends on 1) The method of claim 1, further comprising: receiving, by the PE, configuration data configuring a common anycast Internet Protocol (IP) address for the virtual network interface, wherein the common anycast IP address is assigned by each of the plurality of PE to respective virtual network interfaces for the overlay virtual network for respective links of the Ethernet segment that connects each of the plurality of provider edge devices to the CE. ### Claim 5 (depends on 1) The method of claim 1, further comprising: receiving, by the PE and from the remote PE for the EVPN instance, a Border Gateway Protocol (BGP) message that includes an association of a Multiprotocol Label Switching (MPLS) label and a media access control (MAC) address for a remote customer device; receiving, by the PE at the virtual network interface and from the CE device, a layer 2 packet destined to the MAC address for the remote customer device; and sending, by the PE to the remote PE for the EVPN instance and based on the association of the MPLS label and the MAC address for the remote customer device, a labeled packet that encapsulates the layer 2 packet in the MPLS label. ### Claim 6 (depends on 5) The method of claim 5, where in the BGP message comprises a media access control/Internet Protocol (MAC/IP) Advertisement route type specific EVPN Network Layer Reachability Information for the EVPN instance. ### Claim 7 (depends on 5) The method of claim 5, wherein an overlay tunneling protocol for the overlay virtual network comprises one of Virtual Extensible Local Area Network (VXLAN), Network Virtualization using Generic Route Encapsulation (NVGRE), and Stateless Transport Tunneling (STT). ### Claim 8 (depends on 1) The method of claim 1, wherein the EVPN instance comprises an EVPN data center interconnect (DCI) of a first data center, wherein the first data center comprises the plurality of provider edge devices, wherein the second data center comprises the one or more remote provider edge devices connected to the plurality of provider edge devices of the first data center via the intermediate network. ### Claim 9 (depends on 1) The method of claim 1, wherein the PE comprises a first PE, the method further comprising: triggering, by the first PE in response to determining a failure condition for a second PE of the plurality of provider edge devices, the designated forwarder election for the EVPN instance to elect one of the plurality of PEs as the designated forwarder for the EVPN instance. ### Claim 10 (depends on 9) The method of claim 9, further comprising determining the failure condition based on one of: an indication of core isolation from the intermediate network such that the second PE is unable to send or receive network packets on the intermediate network, an indication that the second PE is unable to send or receive packets on the overlay network, and an indication that the second PE has failed. ### Claim 11 A provider edge device (PE) comprises: a network interface connected to one of a plurality of links of an Ethernet segment by which the PE is one of a plurality of PEs coupled to a multi-homed customer edge device (CE); and one or more processors configured to execute an Ethernet Virtual Private Network (EVPN) instance to provide an EVPN over an intermediate network to one or more remote provide edge devices, wherein the processor is configured to: participate in a designated forwarder (DF) election of one of the PEs for forwarding packets from the EVPN to the customer network by the Ethernet segment; and responsive to being elected the DF, output, according to an interior gateway protocol (IGP) routing protocol, an IGP message specifying a metric for reaching the PE by the respective link of the Ethernet segment to direct the CE to forward network packets from the customer network to the PE. ### Claim 12 (depends on 11) The PE of claim 11, wherein the processor is configured to, responsive to a different one of the PEs being elected the DF for the EVPN, output a second IGP message to modify the metric to indicate a longer routing distance for reaching the PE via the respective link of the Ethernet segment to direct the CE to forward subsequent network packets from the customer network to the different one of the PEs. ### Claim 13 (depends on 12) The PE of claim 12, wherein the metric of the IGP message output when the PE is elected DF comprises a MIN_IGP metric having a minimum permissible value for the IGP routing protocol, and wherein the metric of the second IGP message when a different one of the PEs is elected the DF comprises a MAX_IGP metric having a maximum permissible value for the IGP routing protocol. ### Claim 14 (depends on 11) The PE of claim 11, wherein the processor is configured to execute a tunneling protocol to form an overlay network over the Ethernet segment and assign a virtual network interface for reaching the PE over the respective link of the Ethernet segment. ### Claim 15 (depends on 14) The PE of claim 14, wherein the processor is configured to receive configuration data configuring a common anycast Internet Protocol (IP) address for the virtual network interface of the virtual network formed over the Ethernet segment, and wherein the common anycast IP address is assigned by each of the plurality of PE to respective virtual network interfaces of the overlay virtual network for respective links of the Ethernet segment that connects each of the plurality of provider edge devices to the CE. ### Claim 16 (depends on 14) The PE of claim 14, wherein an overlay tunneling protocol for the overlay virtual network comprises one of Virtual Extensible Local Area Network (VXLAN), Network Virtualization using Generic Route Encapsulation (NVGRE), and Stateless Transport Tunneling (STT). ### Claim 17 (depends on 11) The PE of claim 11, wherein the processor is configured to: receive, from the remote PE for the EVPN instance, a Border Gateway Protocol (BGP) message that includes an association of a Multiprotocol Label Switching (MPLS) label and a media access control (MAC) address for a remote customer device; receive, at the virtual network interface and from the CE device, a layer 2 packet destined to the MAC address for the remote customer device; and send, to the remote PE for the EVPN instance and based on the association of the MPLS label and the MAC address for the remote customer device, a labeled packet that encapsulates the layer 2 packet in the MPLS label. ### Claim 18 (depends on 14) The PE of claim 14, where in the BGP message comprises a media access control/Internet Protocol (MAC/IP) Advertisement route type specific EVPN Network Layer Reachability Information for the EVPN instance. ### Claim 19 (depends on 11) The PE of claim 11, wherein the EVPN instance comprises an EVPN data center interconnect (DCI) of a first data center, wherein the first data center comprises the plurality of provider edge devices, wherein the second data center comprises the one or more remote provider edge devices connected to the plurality of provider edge devices of the first data center via the intermediate network. ### Claim 20 (depends on 11) The PE of claim 11, wherein the processor is configured to trigger, in response to determining a failure condition for a second PE of the plurality of provider edge devices, the designated forwarder election for the EVPN instance to elect one of the plurality of PEs as the designated forwarder for the EVPN instance. ### Claim 21 (depends on 20) The PE of claim 20, wherein the processor is configured to determine the failure condition based on one of: an indication of core isolation from the intermediate network such that the second PE is unable to send or receive network packets on the intermediate network, an indication that the second PE is unable to send or receive packets on the overlay network, and an indication that the second PE has failed. ### Claim 22 (depends on 11) The processor of claim 11, wherein the first metric comprises a MAX_IGP metric having a maximum permissible value for the IGP, and wherein the second metric comprises a MIN_IGP metric having a minimum permissible value for the IGP. ### Claim 23 A non-transitory computer-readable medium comprising instructions for causing one or more programmable processors of a provider edge device (PE) to: execute, with a provider edge device (PE) of a plurality of PEs coupled to a multi-homed customer edge device (CE) by an overlay network formed over an active-standby multi-link Ethernet segment, an Ethernet Virtual Private Network (EVPN) instance to provide an EVPN over an intermediate network to one or more remote provide edge devices; participate, with the PE device, in a designated forwarder (DF) election of one of the PEs for forwarding packets from the EVPN to the customer network by the Ethernet segment; and responsive to the PE being elected the DF, output, with the PE according to an interior gateway protocol (IGP) routing protocol, an IGP message specifying a metric for reaching a virtual network interface of the PE by a respective link of the Ethernet segment to direct the CE to forward network packets from the customer network to the PE.