Using a control plane to set a preferred egress point in multi-site logical routers
In some embodiments, a method receives a selection of a logical router in the first computing device in a first site of a plurality of sites as a preferred egress point to an external network for the logical router. The logical router is instantiated on computing devices in the plurality of sites and a single site in the sites is the preferred egress point for the logical router. The method stores identification information for the logical router in a routing table that stores identification information for multiple logical routers. The identification information is unique among multiple logical routers. The method advertises via a routing instance in a control plane to other computing devices in other sites the identification information for the logical router to indicate the logical router in the first computing device in the first site is the preferred egress point.
1. A method comprising:
receiving, by a first computing device, a selection of a logical router in the first computing device in a first site of a plurality of sites as a preferred egress point to an external network for the logical router, wherein the logical router is instantiated on computing devices in the plurality of sites, and wherein a single site in the plurality of sites is the preferred egress point for the logical router;
storing, by the first computing device, identification information for the logical router in a first table that stores identification information for setting the preferred egress point, wherein the first table is used in a control plane to set the preferred egress point; and
advertising, by the first computing device, via a routing instance in the control plane to other computing devices in other sites in the plurality of sites, the identification information for the logical router to indicate the logical router in the first computing device in the first site is the preferred egress point, wherein a second computing device in a second site uses the identification information to set a next hop address in a second table that the logical router in the second site uses in a data plane to forward packets to the logical router in the first computing device in the first site.
2. The method of claim 1 , further comprising:
generating a first attribute value for the identification information, the first attribute value being generated based on a reference that changes over time, wherein:
the second computing device uses the identification information to identify a second attribute value that was generated based on the reference, and
the second computing device sets the next hop address for the logical router in the second site as the address for the logical router in the first computing device in the first site when the first attribute value is higher in value than the second attribute value.
3. The method of claim 2 , wherein:
after setting the next hop address, the second computing device receives the identification information and the second attribute value, and
the second computing device does not change the next hop address for the logical router in the second site for the logical router in the first computing device in the first site as the address for the logical router in the first computing device in the first site when the second attribute value is lower in value than the first attribute value.
4. The method of claim 1 , wherein:
the selection of the logical router in the first computing device in the first site of the plurality of sites as the preferred egress point is received when another logical router in a second site in the plurality of sites become unreachable, and
the another logical router sets the next hop address as the address for the logical router in the first computing device in the first site when the another logical router is reachable.
5. The method of claim 1 , wherein advertising via the routing instance comprises using a single first table to set the preferred egress point for multiple logical routers.
6. The method of claim 1 , wherein:
multiple preferred egress points for multiple logical routers are advertised in the routing instance, and
the identification information allows the second computing device to uniquely identify the logical router from other logical routers in the first table.
7. The method of claim 1 , wherein:
the logical router comprises a service router that is centralized on an edge node and a distributed router that is distributed across multiple computing devices, and
the service router is distributed on multiple edge nodes in multiple sites and one service router is designated as the preferred egress point for the distributed routers.
8. A non-transitory computer-readable storage medium containing instructions, that when executed, control a first computing device to be operable for:
receiving a selection of a logical router in the first computing device in a first site of a plurality of sites as a preferred egress point to an external network for the logical router, wherein the logical router is instantiated on computing devices in the plurality of sites, and wherein a single site in the plurality of sites is the preferred egress point for the logical router;
storing dentification information for the logical router in a first table that stores identification information for setting the preferred egress point, wherein the first table is used in a control plane to set the preferred egress point; and
advertising, via a routing instance in the control plane to other computing devices in other sites in the plurality of sites, the identification information for the logical router to indicate the logical router in the first computing device in the first site is the preferred egress point, wherein a second computing device in a second site uses the identification information to set a next hop address in a second table that the logical router in the second site uses in a data plane to forward packets to the logical router in the first computing device in the first site.
9. The non-transitory computer-readable storage medium of claim 8 , further operable for:
generating a first attribute value for the identification information, the first attribute value being generated based on a reference that changes over time, wherein:
the second computing device uses the identification information to identify a second attribute value that was generated based on the reference, and
the second computing device sets the next hop address for the logical router in the second site as the address for the logical router in the first computing device in the first site when the first attribute value is higher in value than the second attribute value.
10. The non-transitory computer-readable storage medium of claim 9 , wherein:
after setting the next hop address, the second computing device receives the identification information and the second attribute value, and
the second computing device does not change the next hop address for the logical router in the second site for the logical router in the first computing device in the first site as the address for the logical router in the first computing device in the first site when the second attribute value is lower in value than the first attribute value.
11. The non-transitory computer-readable storage medium of claim 8 , wherein:
the selection of the logical router in the first computing device in the first site of the plurality of sites as the preferred egress point is received when another logical router in a second site in the plurality of sites become unreachable, and
the another logical router sets the next hop address as the address for the logical router in the first computing device in the first site when the another logical router is reachable.
12. The non-transitory computer-readable storage medium of claim 8 , wherein advertising via the routing instance comprises using a single first table to set the preferred egress point for multiple logical routers.
13. The non-transitory computer-readable storage medium of claim 8 , wherein:
multiple preferred egress points for multiple logical routers are advertised in the routing instance, and
the identification information allows the second computing device to uniquely identify the logical router from other logical routers in the first table.
14. The non-transitory computer-readable storage medium of claim 8 , wherein:
the logical router comprises a service router that is centralized on an edge node and a distributed router that is distributed across multiple computing devices, and
the service router is distributed on multiple edge nodes in multiple sites and one service router is designated as the preferred egress point for the distributed routers.
15. A first computing device comprising:
one or more computer processors; and
a non-transitory computer-readable storage medium comprising instructions, that when executed, control the one or more computer processors to be operable for:
receiving a selection of a logical router in the first computing device in a first site of a plurality of sites as a preferred egress point to an external network for the logical router, wherein the logical router is instantiated on computing devices in the plurality of sites, and wherein a single site in the plurality of sites is the preferred egress point for the logical router;
storing dentification information for the logical router in a first table that stores identification information for setting the preferred egress point, wherein the first table is used in a control plane to set the preferred egress point; and
advertising, via a routing instance in the control plane to other computing devices in other sites in the plurality of sites, the identification information for the logical router to indicate the logical router in the first computing device in the first site is the preferred egress point, wherein a second computing device in a second site uses the identification information to set a next hop address in a second table that the logical router in the second site uses in a data plane to forward packets to the logical router in the first computing device in the first site.
16. The apparatus of claim 15 , further operable for:
generating a first attribute value for the identification information, the first attribute value being generated based on a reference that changes over time, wherein:
the second computing device uses the identification information to identify a second attribute value that was generated based on the reference, and
the second computing device sets the next hop address for the logical router in the second site as the address for the logical router in the first computing device in the first site when the first attribute value is higher in value than the second attribute value.
17. The apparatus of claim 16 , wherein:
after setting the next hop address, the second computing device receives the identification information and the second attribute value, and
the second computing device does not change the next hop address for the logical router in the second site for the logical router in the first computing device in the first site as the address for the logical router in the first computing device in the first site when the second attribute value is lower in value than the first attribute value.
18. The apparatus of claim 15 , wherein:
the selection of the logical router in the first computing device in the first site of the plurality of sites as the preferred egress point is received when another logical router in a second site in the plurality of sites become unreachable, and
the another logical router sets the next hop address as the address for the logical router in the first computing device in the first site when the another logical router is reachable.
19. The apparatus of claim 15 , wherein advertising via the routing instance comprises using a single first table to set the preferred egress point for multiple logical routers.
20. The apparatus of claim 15 , wherein:
multiple preferred egress points for multiple logical routers are advertised in the routing instance, and
the identification information allows the second computing device to uniquely identify the logical router from other logical routers in the first table.
21. The apparatus of claim 15 , wherein:
the logical router comprises a service router that is centralized on an edge node and a distributed router that is distributed across multiple computing devices, and
the service router is distributed on multiple edge nodes in multiple sites and one service router is designated as the preferred egress point for the distributed routers.