Seamless host mobility

An apparatus comprising:

• a plurality of network interface ports configured to enable network communications;
• and
• a processor, coupled to the plurality of network interface ports, and configured to:
• in response to a host moving from a first Ethernet virtual private network (EVPN) domain to a second EVPN domain connected to the first EVPN domain by an external network, each EVPN domain configured to perform traffic routing for host devices based on routing information including sequence numbers that are incremented when hosts move to indicate most up-to-date routing information, wherein the external network is not configured to directly carry the sequence numbers between the first EVPN domain and the second EVPN domain, receive for the host device updated routing information including an updated sequence number that is larger than a sequence number previously associated with the host device when previously located in the first EVPN domain;
• and
• in response to the receiving for the host the updated routing information, upon determining that the host device has moved:
• send to the host device in the second EVPN domain a targeted host announcement message configured to enable the second EVPN domain to establish routing information for the host device in the second EVPN domain;
• convert, using a subtraction operation, the updated sequence number to a converted sequence number able to be carried by the external network;
• and
• send the converted sequence number over the external network to a border leaf node of the second domain so that the border leaf node is able to extract and use the updated sequence number for traffic routing with respect to the host device in order to avoid use of inconsistent and stale routing information in the second EVPN domain.

One or more non-transitory computer readable storage media encoded with instructions that, when executed by a processor of a leaf node in a first Ethernet virtual private network (EVPN) domain connected to a second EVPN domain via an external network, each EVPN domain configured to perform traffic routing for hosts based on routing information including sequence numbers that are incremented when hosts move to indicate most up-to-date routing information, wherein the external network is not configured to directly carry the sequence numbers between the first EVPN domain and the second EVPN domain, cause the processor to:

• in response to a host moving from the first EVPN domain to the second EVPN domain, receive for the host updated routing information including an updated sequence number that is larger than a sequence number previously associated with the host when previously located in the first EVPN domain;
• and
• in response to receiving for the host the updated routing information, upon determining that the host has moved:
• send to the host in the second EVPN domain a targeted host announcement message configured to enable the second EVPN domain to establish routing information for the host in the second EVPN domain;
• convert, using a subtraction operation, the updated sequence number to a converted sequence number able to be carried by the external network;
• and
• send the converted sequence number over the external network to a border leaf node of the second domain so that the border leaf node is able to extract and use the updated sequence number for traffic routing with respect to the host in order to avoid use of inconsistent and stale routing information in the second EVPN domain.