Avoiding traffic flooding for known unicast traffic when an EVPN is inter-connected to a data plane VXLAN in all-active mode

1. For use in a system including an Ethernet Virtual Private Network (EVPN) core network and a virtual extensible local area network (VXLAN) data plane, a first gateway device (GW1) and a second gateway device (GW2) operating in an all-active multihoming mode to interconnect the EVPN core network and VXLAN data plane, a computer-implemented method comprising:

establishing, by the second gateway device GW2, operating with the first gateway device GW1 in an all-active multihoming mode to interconnect the EVPN core network and the VXLAN dataplane, a VXLAN tunnel to a remote VXLAN tunnel end point (VTEP) X in the VXLAN before traffic is sent by the remote VTEP X and received by the second gateway device GW2, but after traffic is sent by the remote VTEP X and received by the first gateway device GW1, by:

proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2; and

establishing, by the second gateway device GW2 and responsive to receiving the ARP packet, a VXLAN tunnel from the second gateway device GW2 to the remote VTEP X,

wherein the first and second gateway devices GW1 and GW2 use an anycast Internet protocol (IP) address as a source address for VTEP X.

2. The method of claim 1 , wherein the act of proactively forcing, by the second gateway device GW2, the remote VTEP X to send an ARP packet from an attached host, to the second gateway device GW2, includes:

receiving, by the second gateway device GW2, a type-2 route for a media access control (MAC) and IP address of host A, including an Ethernet Segment Identifier (ESI), from the first gateway device GW1;

learning, by the second gateway device GW2, a multihomed Ethernet Segment Identifier (ESI) and a bridge domain of host A from the type-2 route;

determining, by the second gateway device GW2, and based on the multihoming ESI associated with the type-2 route, that host A is behind the VXLAN data plane network instead of a regular customer edge (CE) device; and

flooding, by the second gateway device GW2, an ARP request to a plurality of remote VTEPs on the VXLAN, including VTEP X.

3. The method of claim 1 , wherein the act of proactively forcing, by the second gateway device GW2, the remote VTEP X to send an ARP packet from an attached host, to the second gateway device GW2, includes:

receiving, by the second gateway device GW2, a type-2 route for a MAC address and an IP address (MAC/IP) of host A, including an Ethernet Segment Identifier (ESI), from the first gateway device GW1;

checking, by the second gateway device GW2, whether the MAC/IP is associated with an established data plane VXLAN tunnel; and

responsive to a determination by the second gateway device GW2 that the second gateway device GW2 cannot find an established data plane VXLAN tunnel associated with the MAC/IP,

1) generating, by the second gateway device GW2, a host generated ARP request packet for host A's IP address received in the type-2 route,

wherein an outer IP header of the host-generated ARP packet has a unique lookback address of the second gateway device GW2 as the source IP address and a multicast group for the bridge domain as a destination IP address, and

wherein an inner ARP request packet has a source IP/MAC set to GW2's integrated routing and bridging's (IRB's) unique MAC/IP address, and

2) delivering the host-generated ARP request to host A through an underlay PIM to all remote VTEPs of the VXLAN.

4. The method of claim 2 , wherein the host-generated ARP request triggers data plane learning at the remote VTEPs of the VXLAN.

5. The method of claim 4 , wherein the remote VTEP X learns the unique loopback address of the second gateway device GW2 and establishes a VXLAN tunnel to the second gateway device GW2 if it had not already done so.

6. The method of claim 5 , wherein the remote VTEP X also learns GW2's IRB's MAC/IP is behind its VXLAN tunnel to GW2,

whereby, when a unicast ARP reply comes back from host A, this time the remote VTEP X sends the unicast ARP reply to the second gateway device GW2 directly such that the second gateway device GW2 has forced the remote VTEP X to send a data packet to it.

7. The method of claim 6 , further comprising:

updating, by the second gateway device GW2, a forwarding entry for host A's MAC, whereby it becomes unnecessary for the gateway device GW2 to flood traffic destinated to host A and whereby blackholing is avoided by any non-designated forwarder gateway device;

receiving, by the second gateway device GW2, unicast traffic to host A; and

forwarding the unicast traffic to host A using the forwarding entry, without flooding and without traffic blackholing.

8. For use in a system including an Ethernet Virtual Private Network (EVPN) core network and a virtual extensible local area network (VXLAN) data plane, a second gateway device (GW2) which, together with a first gateway device (GW1), operates in an all-active multihoming mode to interconnect the EVPN core network and VXLAN data plane, the second gateway device comprising:

at least one processor; and

a storage device storing processor-executable instructions which, when executed by the at least one processor, cause the at least one processor to

establish, by the second gateway device GW2, operating with the first gateway device GW1 in an all-active multihoming mode to interconnect the EVPN core network and the VXLAN dataplane, a VXLAN tunnel to a remote VXLAN tunnel end point (VTEP) X of the VXLAN before traffic is sent by the remote VTEP X and received by the second gateway device GW2, but after traffic is sent by the remote VTEP X and received by the first gateway device GW1, by:

proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2; and

establishing, by the second gateway device GW2 and responsive to receiving the packet, a VXLAN tunnel from the second gateway device GW2 to the remote VTEP X,

wherein the first and second gateway devices GW1 and GW2 use an anycast address as a source address for VTEP X.

9. A non-transitory computer-readable storage medium storing processor-executable instructions which, when executed by at least one processor, cause the at least one processor to perform a method for use in a system including an Ethernet Virtual Private Network (EVPN) core network and a VXLAN data plane, a first gateway device GW1 and a second gateway device GW2 operating in an all-active multihoming mode to interconnect the EVPN core network and VXLAN data plane, the method comprising:

establishing, by the second gateway device GW2, operating with the first gateway device GW1 in an all-active multihoming mode to interconnect the EVPN core network and the VXLAN dataplane, a VXLAN tunnel to a remote VTEP X in the VXLAN before traffic is sent by the remote VTEP X and received by the second gateway device GW2, but after traffic is sent by the remote VTEP X and received by the first gateway device GW1, by:

proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2; and

establishing, by the second gateway device GW2 and responsive to receiving the packet, a VXLAN tunnel from the second gateway device GW2 to the remote VTEP X,

wherein the first and second gateway devices GW1 and GW2 use an anycast address as a source address for VTEP X.

10. The second gateway device of claim 8 , wherein the act of proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2, includes:

receiving, by the second gateway device GW2, a type-2 route for a media access control (MAC) and IP address (MAC/IP) of host A, including an Ethernet Segment Identifier (ESI), from the first gateway device GW1;

learning, by the second gateway device GW2, a multihomed Ethernet Segment Identifier (ESI) and a bridge domain of host A from the type-2 route;

determining, by the second gateway device GW2, and based on the multihoming ESI associated with the type-2 route, that host A is behind the VXLAN data plane network instead of a regular customer edge (CE) device; and

flooding, by the second gateway device GW2, an ARP request to a plurality of remote VTEPs on the VXLAN, including VTEP X.

11. The second gateway device of claim 10 , wherein the host-generated ARP request triggers data plane learning at the remote VTEPs of the VXLAN.

12. The second gateway of claim 11 , wherein the remote VTEP X learns the unique loopback address of the second gateway device GW2 and establishes a VXLAN tunnel to the second gateway device GW2 if it had not already done so.

13. The second gateway of claim 12 , wherein the remote VTEP X also learns GW2's IRB's MAC/IP is behind its VXLAN tunnel to GW2,

whereby, when a unicast ARP reply comes back from host A, this time the remote VTEP X sends the unicast ARP reply to the second gateway device GW2 directly such that the second gateway device GW2 has forced the remote VTEP X to send a data packet to it.

14. The second gateway of claim 13 , wherein the processor-executable instructions which, when executed by the at least one processor, further cause the at least one processor to:

update, by the second gateway device GW2, a forwarding entry for host A's MAC, whereby it becomes unnecessary for the gateway device GW2 to flood traffic destinated to host A and whereby blackholing is avoided by any non-designated forwarder gateway device;

receive, by the second gateway device GW2, unicast traffic to host A; and

forward the unicast traffic to host A using the forwarding entry, without flooding and without traffic blackholing.

15. The second gateway device of claim 8 , wherein the act of proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2, includes:

receiving, by the second gateway device GW2, a type-2 route for a MAC address and an IP address of host A, including an Ethernet Segment Identifier (ESI), from the first gateway device GW1;

checking, by the second gateway device GW2, whether the MAC/IP is associated with an established data plane VXLAN tunnel; and

responsive to a determination by the second gateway device GW2 that the second gateway device GW2 cannot find an established data plane VXLAN tunnel associated with the media access control/Internet protocol (MAC/IP),

1) generating, by the second gateway device GW2, a host generated ARP request packet for host A's IP address received in the type-2 route,

wherein an outer IP header of the host-generated ARP packet has a unique lookback address of the second gateway device GW2 as the source IP address and a multicast group for the bridge domain as a destination IP address, and

wherein an inner ARP request packet has a source IP/MAC set to GW2's integrated routing and bridging's (IRB's) unique MAC/IP address, and

2) delivering the host-generated ARP request to host A through an underlay PIM to all remote VTEPs of the VXLAN.

16. The non-transitory computer-readable medium of claim 9 , wherein the host-generated ARP request triggers data plane learning at the remote VTEPs of the VXLAN.

17. The non-transitory computer-readable medium of claim 16 , wherein the remote VTEP X learns the unique loopback address of the second gateway device GW2 and establishes a VXLAN tunnel to the second gateway device GW2 if it had not already done so.

18. The non-transitory computer-readable medium of claim 17 , wherein the remote VTEP X also learns GW2's IRB's MAC/IP is behind its VXLAN tunnel to GW2,

whereby, when a unicast ARP reply comes back from host A, this time the remote VTEP X sends the unicast ARP reply to the second gateway device GW2 directly such that the second gateway device GW2 has forced the remote VTEP X to send a data packet to it.

19. The non-transitory computer-readable medium of claim 18 , wherein the processor-executable instructions which, when executed by the at least one processor, further cause the at least one processor to:

update, by the second gateway device GW2, a forwarding entry for host A's MAC, whereby it becomes unnecessary for the gateway device GW2 to flood traffic destinated to host A and whereby blackholing is avoided by any non-designated forwarder gateway device;

receive, by the second gateway device GW2, unicast traffic to host A; and

forward the unicast traffic to host A using the forwarding entry, without flooding and without traffic blackholing.

20. The non-transitory computer-readable medium of claim 19 , wherein the act of proactively forcing, by the second gateway device GW2, the remote VTEP X to send an address resolution protocol (ARP) packet from an attached host, to the second gateway device GW2, includes:

receiving, by the second gateway device GW2, a type-2 route for a MAC address and an IP address of host A, including an Ethernet Segment Identifier (ESI), from the first gateway device GW1;

checking, by the second gateway device GW2, whether the MAC/IP is associated with an established data plane VXLAN tunnel; and

responsive to a determination by the second gateway device GW2 that the second gateway device GW2 cannot find an established data plane VXLAN tunnel associated with the media access control/Internet protocol (MAC/IP),

1) generating, by the second gateway device GW2, a host generated ARP request packet for host A's IP address received in the type-2 route,

wherein an outer IP header of the host-generated ARP packet has a unique lookback address of the second gateway device GW2 as the source IP address and a multicast group for the bridge domain as a destination IP address, and

wherein an inner ARP request packet has a source IP/MAC set to GW2's integrated routing and bridging's (IRB's) unique MAC/IP address, and

2) delivering the host-generated ARP request to host A through an underlay PIM to all remote VTEPs of the VXLAN.