DCI stitching for data center overlays

1. A method comprising:

storing a route stitching table at a datacenter interconnect network element, wherein the datacenter interconnect network element provides for routing transmissions between at least a first domain and a second domain, the first domain and the second domain comprising different control planes, the route stitching table comprising one or more first route target values for a first route target set associated with the first domain and one or more second route target values for a second route target set associated the second domain, and the first route target set is associated with a first indicator tag and the second route target set is associated with a second indicator tag;

receiving by the datacenter interconnect network element a routing update from a first network element the first domain, the routing update comprising a first routing prefix comprising a particular first route target value;

determining, based on the route stitching table, that the particular first route target value is associated with the first route target set associated with the first domain;

identifying, via the route stitching table, the second route target set associated with the second domain;

creating a second routing prefix that includes the one or more second route target values from the second route target set; and

transmitting the second routing prefix to a network element in the second domain.

2. The method of claim 1 , wherein the routing update is received from one of a border leaf node or a top-of-rack (TOR) switch in the first domain.

3. The method of claim 1 , wherein transmitting the second routing prefix comprises transmitting the second routing prefix to an autonomous system boundary router (ASBR) in the second domain.

4. The method of claim 1 , wherein the first domain comprises a Layer 2 (L2) virtual private network.

5. The method of claim 1 , wherein the second domain comprises a Layer 3 (L3) virtual private network.

6. The method of claim 1 , wherein receiving the routing update further comprises receiving, from the first network element a border gateway protocol (BGP) routing update comprising the first routing prefix.

7. The method of claim 6 , wherein creating the second routing prefix comprises:

copying the BGP routing update; and

mapping the one or more second route target values from the second route target set to the BGP routing update.

8. A datacenter interconnect (DCI) network element comprising:

at least one memory element having instructions stored thereon;

at least one processors coupled to the at least one memory element and configured to execute the instructions to cause the DCI network element to:

store a route stitching table, wherein the DCI network element is to route transmissions between at least a first domain and a second domain, the first domain and the second domain comprising different control planes, the route stitching table comprising one or more first route target values for a first route target set associated with the first domain and one or more second route target values for a second route target set associated the second domain, and the first route target set is associated with a first indicator tag and the second route target set is associated with a second indicator tag;

receive a routing update from a first network element of the first domain, the routing update comprising a first routing prefix comprising a particular first route target value;

determine, based on the route stitching table, that the particular first route target value is associated with the first route target set, the first route target set associated with the first domain;

identify, via the route stitching table, the second route target set associated with the second domain;

create a second routing prefix that includes the one or more second route target values from the second route target set; and

transmit the second routing prefix to a network element in the second domain.

9. The DCI network element of claim 8 , wherein the routing update is received from one of a border leaf node or a top-of-rack (TOR) switch in the first domain.

10. The DCI network element of claim 8 , wherein transmitting the second routing prefix comprises transmitting the second routing prefix to an autonomous system boundary router (ASBR) in the second domain.

11. The DCI network element of claim 8 , wherein the first domain comprises a Layer 2 (L2) virtual private network.

12. The DCI network element of claim 8 , wherein the second domain comprises a Layer 3 (L3) virtual private network.

13. The DCI network element of claim 8 , wherein receiving the routing update further comprises receiving, from the first network element, a border gateway protocol (BGP) routing update comprising the first routing prefix.

14. The DCI network element of claim 13 , wherein creating the second routing prefix comprises:

copying the BGP routing update; and

mapping the one or more second route target values from the second route target set to the BGP routing update.

15. A system comprising:

a first network element of a first virtual private networking (VPN) domain; and

a datacenter interconnect (DCI) network element comprising:

at least one memory element having instructions stored thereon;

at least one processors coupled to the at least one memory element and configured to execute the instructions to cause the DCI network element to:

store a route stitching table, wherein the DCI network element is to route transmissions between at least the first VPN domain and a second VPN domain, the first VPN domain and the second VPN domain comprising different control planes, the route stitching table comprising one or more first route target values for a first route target set associated with the first VPN domain and one or more second route target values for a second route target set associated the second VPN domain, and the first route target set is associated with a first indicator tag and the second route target set is associated with a second indicator tag;

receive a routing update from a first network element of the first VPN domain, the routing update comprising a first routing prefix comprising a particular first route target value;

determine, based on the route stitching table, that the particular first route target value is associated with the first route target set associated with the first VPN domain;

identify, via the route stitching table, the second route target set associated with the second VPN domain;

create a second routing prefix that includes the one or more second route target values from the second route target set; and

transmit the second routing prefix to a network element in the second VPN domain.

16. The system of claim 15 , wherein the first network element comprises as autonomous system boundary router (ASBR), and wherein the routing update is received from the ASBR in the first VPN domain.

17. The system of claim 15 , wherein the transmitting the second routing prefix comprises transmitting the second routing prefix to an autonomous system boundary router (ASBR) in the second VPN domain.

18. The system of claim 15 , wherein the first VPN domain comprises a Layer 3 (L3) virtual private network.

19. The system of claim 15 , wherein the second VPN domain comprises a Layer 2 (L2) virtual private network.

20. The system of claim 15 , wherein receiving the routing update further comprises receiving, from the first network element a border gateway protocol (BGP) routing update comprising the first routing prefix.

21. The system of claim 20 , wherein creating the second routing prefix comprises:

copying the BGP routing update; and

mapping the one or more second route target values from the second route target set to the BGP routing update.