Overlay route optimization across data centers
The distribution of reachability information between data centers includes receiving routes that are advertised among network devices within a given data center. The received routes are summarized to produce one or more summarized (aggregated) routes which are fewer in number than the received routes. Instead of advertising the received routes among the data centers, the summarized routes are advertised. Advertising the summarized routes as compared to the received routes reduces control plane traffic between data centers, and reduces the requirements for storing advertised routes received by a data center.
1. A method performed by a network device in a first network domain, the method comprising
receiving a plurality of EVPN (Ethernet virtual private network) Type 5 routes, each EVPN Type 5 route including a network prefix;
identifying a plurality of network prefixes from the received EVPN Type 5 routes;
summarizing the identified plurality of network prefixes to produce a summarized network prefix;
generating an aggregated EVPN Type 5 route comprising the summarized network prefix and a next hop identifier that identifies the network device as a next hop; and
advertising the aggregated EVPN Type 5 route to another network device in a second network domain different from the first network domain,
wherein the advertising of the aggregated EVPN Type 5 route communicates the summarized network prefix to said another network device in the second network domain while avoiding communication of the plurality of network prefixes to said another network device in the second network domain.
2. The method of claim 1 , wherein the network device is a gateway device in the first network domain, and wherein said another network device is a gateway device in the second network domain.
3. The method of claim 1 , wherein the identified plurality of network prefixes correspond to contiguous subnets.
4. The method of claim 1 , further comprising advertising the aggregated EVPN Type 5 route in a BGP (border gateway protocol) update message.
5. The method of claim 1 , wherein the network device receives the plurality of EVPN Type 5 routes from other network devices in the first network domain.
6. The method of claim 1 , wherein summarizing the plurality of network prefixes includes defining a network prefix that contains the plurality of network prefixes.
7. A method performed by a network device in a first network domain, the method comprising:
receiving a plurality of EVPN Type 2 routes, each EVPN Type 2 route including a MAC-IP binding;
storing a MAC to IP mapping in a memory of the network device according to the MAC-IP binding in each received EVPN Type 2 route;
summarizing a plurality of IP addresses in the plurality of EVPN Type 2 routes to produce a summarized network prefix;
generating an aggregated EVPN Type 5 route comprising the summarized network prefix and a next hop identifier that identifies the network device as a next hop; and advertising the aggregated EVPN Type 5 route to another network device in a second network domain different from the first network domain, wherein the advertising of the aggregated EVPN Type 5 route communicates the summarized network prefix to said another network device in the second network domain while avoiding communication of the plurality of IP addresses to said another network device in the second network domain.
8. The method of claim 7 , wherein the network device is a gateway device in the first network domain, and wherein said another network device is a gateway device in the second network domain.
9. The method of claim 7 , further comprising advertising the aggregated EVPN Type 5 route in a BGP (border gateway protocol) update message.
10. The method of claim 7 , wherein the network device receives the plurality of EVPN Type 2 routes from other network devices in the first network domain.
11. The method of claim 7 , wherein the summarized network prefix represents a subnet that encompasses the plurality of IP addresses.
12. The method of claim 7 , wherein the plurality of IP addresses are contiguous.
13. A network device in a first overlay network, the network device comprising:
one or more computer processors; and
a non-transitory computer-readable storage medium comprising instructions for controlling the one or more computer processors to:
receive a plurality of EVPN Type 5 routes comprising a respective plurality of IP prefixes;
update one or more forwarding tables of the network device based on the plurality of IP prefixes;
combine the plurality of IP prefixes to produce a summarized IP prefix that represents an aggregation of the plurality of IP prefixes;
advertise an overlay route comprising the summarized IP prefix to at least another network device in at least a second overlay network separate from the first overlay network, wherein the advertising of the overlay route communicates the summarized IP prefix to said another network device in the second overlay network while avoiding communication of the plurality of IP prefixes to said another network device in the second overlay network.
14. The network device of claim 13 , wherein the second overlay route is an EVPN Type 5 route.
15. The network device of claim 13 , wherein the network device in the first overlay network is a gateway device, wherein said another network device in the other second overlay network is a gateway device.
16. The network device of claim 13 , wherein the plurality of first IP prefixes are contiguous IP prefixes.