Leveraging multicast listener discovery for discovering hosts
Techniques for leveraging MLD capabilities at edge nodes of network fabrics to receive SNMAs from silent hosts, and creating unicast addresses from the SNMAs for the silent nodes that are used as secondary matches in a network overlay if primary unicast address lookups fail. The edge nodes described herein may act as snoopers of MLD reports in order to identify the SNMAs of the silent hosts. The edge nodes then forge unicast addresses for the silent hosts that match with the least three bytes of the SNMAs. The forged unicast addresses are presented as unicast MAC/IP mappings in the fabric overlay. In situations where a primary IP address lookup fails, the look-up device performs a secondary lookup for a mapped address that has the last three bytes of the IP address. If a mapping is found, the lookup is sent as a unicast message to the matching MAC address.
1. A method comprising:
receiving, at a mapping system that maintains network routes between a first fabric edge and a second fabric edge, a forged Internet Protocol (IP) unicast address sent from a first edge node of the first fabric edge, the forged IP unicast address being usable to identify a host node until an IP unicast address for the host node is determined;
updating, at the mapping system, a global mapping database indicating a route to the host node associated with the forged IP unicast address;
receiving, at the mapping system, a look-up message from a second edge node in the second fabric edge, the look-up message including a request for a route to send data packets to the IP unicast address;
determining, using the global mapping database, that a first portion of the forged IP unicast address matches with a second portion of the IP unicast address; and
providing the second edge node with the route to the host node based at least in part on the first portion of the forged IP unicast address corresponding to the second portion of the IP unicast address and the forged IP unicast address being associated with the route.
2. The method of claim 1 , wherein determining that the first portion of the forged IP unicast address matches with the second portion of the IP unicast address includes determining that at least three least-significant bytes of the forged IP unicast address correspond to at least three least-significant bytes of the IP unicast address.
3. The method of claim 1 , further comprising updating the global mapping database to replace the forged IP unicast address with the IP unicast address such that the route to the host node is associated with the IP unicast address.
4. The method of claim 1 , further comprising sending advertisement messages to nodes in the first fabric edge and the second fabric edge indicating the route to the host node associated with the IP unicast address.
5. The method of claim 1 , further comprising:
determining that the IP unicast address does not have an entry in the global mapping database; and
searching the global mapping database using at least three least-significant bytes of the IP unicast address to identify the forged IP unicast address.
6. The method of claim 1 , wherein the mapping system includes at least one of:
a Locator/ID Separation Protocol (LISP) Map-Server/Map Resolver (MSMR) server; or
an ethernet Virtual Private Network (eVPN) control-plane server.
7. The method of claim 1 , wherein the mapping system is a Locator/ID Separation Protocol (LISP) Map-Server/Map Resolver (MSMR) database that is distributed on multiple network nodes associated with the first fabric edge and the second fabric edge.
8. A mapping system comprising:
one or more processors; and
one or more non-transitory computer-readable media storing computer-executable instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
receiving a forged Internet Protocol (IP) unicast address sent from a first edge node of a first fabric edge, the forged IP unicast address being with usable to identify a host node until an IP unicast address for the host node is determined;
updating a global mapping database indicating a route to the host node associated with the forged IP unicast address;
receiving a look-up message from a second edge node in a second fabric edge, the look-up message including a request for a route to send a data packets to the IP unicast address;
determining, using the global mapping database, that a first portion of the forged IP unicast address matches with a second portion of the IP unicast address; and
causing the data packets to be sent to the first edge node based at least in part on the first determining, using the global mapping database, that a first portion of the forged IP unicast address associated with the route to the host node corresponds to a second portion of the IP unicast address.
9. The mapping system of claim 8 , wherein determining that the first portion of the forged IP unicast address matches with the second portion of the IP unicast address includes determining that at least three least-significant bytes of the forged IP unicast address correspond to at least three least-significant bytes of the IP unicast address.
10. The mapping system of claim 8 , the operations further comprising updating the global mapping database to replace the forged IP unicast address with the IP unicast address such that the route to the host node is associated with the IP unicast address.
11. The mapping system of claim 8 , the operations further comprising sending advertisement messages to nodes in the first fabric edge and the second fabric edge indicating the route to the host node associated with the IP unicast address.
12. The mapping system of claim 8 , the operations further comprising:
determining that the IP unicast address does not have an entry in the global mapping database; and
searching the global mapping database using at least three least-significant bytes of the IP unicast address to identify the forged IP unicast address.
13. The mapping system of claim 8 , further comprising at least one of:
a Locator/ID Separation Protocol (LISP) Map-Server/Map Resolver (MSMR) server; or
an ethernet Virtual Private Network (eVPN) control-plane server.
14. The mapping system of claim 8 , wherein the mapping system includes a Locator/ID Separation Protocol (LISP) Map-Server/Map Resolver (MSMR) database that is distributed on multiple network nodes associated with the first fabric edge and the second fabric edge.
15. One or more non-transitory computer-readable media storing computer-executable instructions that, when executed by one or more processors, cause the one or more processors to perform operations comprising:
receiving, at a mapping system that maintains network routes between a first fabric edge and a second fabric edge, a forged Internet Protocol (IP) unicast address sent from a first edge node of the first fabric edge, the forged IP unicast address being with usable to identify a host node until an IP unicast address for the host node is determined;
updating, at the mapping system, a global mapping database indicating a route to the host node associated with the forged IP unicast address;
receiving, at the mapping system, a look-up message from a second edge node in the second fabric edge, the look-up message including a request for a route to send data packets to the IP unicast address;
determining, using the global mapping database, that a first portion of the forged IP unicast address matches with a second portion of the IP unicast address; and
providing the second edge node with the route to the host node based at least in part on the first portion of the forged IP unicast address corresponding to the second portion of the IP unicast address and the forged IP unicast address being associated with the route.
16. The one or more non-transitory computer-readable media of claim 15 , wherein determining that the first portion of the forged IP unicast address matches with the second portion of the IP unicast address includes determining that at least three least-significant bytes of the forged IP unicast address correspond to at least three least-significant bytes of the IP unicast address.
17. The one or more non-transitory computer-readable media of claim 15 , the operations further comprising updating the global mapping database to replace the forged IP unicast address with the IP unicast address such that the route to the host node is associated with the IP unicast address.
18. The one or more non-transitory computer-readable media of claim 15 , the operations further comprising sending advertisement messages to nodes in the first fabric edge and the second fabric edge indicating the route to the host node associated with the IP unicast address.
19. The one or more non-transitory computer-readable media of claim 15 , the operations further comprising:
determining that the IP unicast address does not have an entry in the global mapping database; and
searching the global mapping database using at least three least-significant bytes of the IP unicast address to identify the forged IP unicast address.
20. The one or more non-transitory computer-readable media of claim 15 , wherein the mapping system includes at least one of:
a Locator/ID Separation Protocol (LISP) Map-Server/Map Resolver (MSMR) server; or
an ethernet Virtual Private Network (eVPN) control-plane server.