Systems and methods to route over a link aggregation group to a true next hop
Various embodiments of the invention allow for rapid communication in virtual link trunking (VLT) networks in which network traffic flows over not all-homed VLT peer devices, while honoring Equal Cost Multi Path (ECMP) decisions and normal route decisions about next hops. Traffic flow is made deterministic and free of sub-optimal paths that otherwise cause unnecessary traffic over inter-node links in the VLT domain. In embodiments, this is accomplished by using receiving VLAN interface-IP addresses from VLT devices in order to create and use a sub-LAG egress table from which sets of ports that lead to intended VLT devices are derived. In embodiments, instead of a VLAN interface-IP addresses a routing MAC address is used when forming the sub-LAG.
1. A method to facilitate routing to the actual next hop in Link Aggregation Group (LAG), the method comprising:
receiving packets at a routing device from at least one node of a plurality of LAG peer nodes, each packet comprising a routing information;
associating the routing information with a sub-LAG having a sub-LAG ID, the sub-LAG represents a subset of ports on the routing device and is associated with a parent LAG having a parent LAG ID;
generating an egress table that associates the sub-LAG with the subset of ports and one or more LAG peer nodes from the plurality of LAG peer nodes, the sub-LAG having been formed by using Link Layer Discovery Protocol (LLDP) information to group a set of links that connect to a unique LAG peer node;
in response to receiving a packet from a host, using the egress table to identify the actual next hop LAG peer node; and
sending the packet on the identified sub-LAG to an intended network node using the sub-LAG ID.
2. The method according to claim 1 , wherein the routing information comprises a VLAN ID and a LAG peer device IP address.
3. The method according to claim 2 , wherein the packets comprise information in an organization-specific TLV.
4. The method according to claim 1 , wherein sub-LAG has been formed in a setup phase.
5. A method to facilitate routing to the actual next hop in Link Aggregation Group (LAG), the method comprising:
receiving, from a host, packets at a routing device in a path to an intended network node;
determining a next hop routing address from a route table stored in memory;
based on the next hop routing address, looking up in an Address Resolution Protocol (ARP) table an entry for an egress interface data, the egress interface data corresponding to a routing information;
in response to receiving a packet from a host, determining from the egress interface data an egress interface that is associated with a sub-LAG having a sub-LAG ID, the sub-LAG is associated with a parent LAG that has a parent LAG ID;
identifying one or more ports communicatively coupled to one or more LAG peer nodes from the plurality of LAG peer nodes; and
using the egress interface to send the packet on the sub-LAG to the intended network node using the sub-LAG ID, the sub-LAG having been formed by using Link layer Discovery Protocol (LLDP) information to group a set of links that connect to a unique LAG peer node.
6. The method according to claim 5 , wherein the egress table allows for a predetermined destination IP an equal-cost multi-path (ECMP) decision to determine an ECMP routing path via an ECMP next hop.
7. The method according to claim 6 , wherein the ECMP hashing decision determines a next hop that has the next hop routing address and is reachable via a single port, the single port being chosen from the sub-LAG via LAG hashing.
8. The method according to claim 5 , further comprising adding the egress interface data to the ARP table.
9. The method according to claim 8 , wherein adding the egress interface data to the ARP table comprises writing the sub-LAG ID into the ARP table to cause the ARP table to point to a sub-LAG that leads to the intended network node.
10. The method according to claim 5 , wherein the egress interface data is associated with the sub-LAG ID.
11. The method according to claim 5 , wherein the egress table is generated by:
receiving packets at a routing device from a plurality of LAG peer nodes, each packet comprising a routing information;
associating the routing information with a sub-LAG having a sub-LAG ID, the sub-LAG represents a subset of ports on the routing device; and
generating an egress table that associates the routing information with the subset of ports and the sub-LAG.
12. The method according to claim 5 , wherein the routing information comprises a VLAN ID and a peer device IP address.
13. The method according to claim 5 , further comprising an ingress LAG table that associates ingress traffic with the parent LAG to receive ingress packets exclusively on the parent LAG to avoid L2 MAC address learning on sub-LAGs and avoid L2 MAC address moves between two or more sub-LAGs.
14. The method according to claim 5 , further comprising updating the egress interface data to point to the parent LAG in instances of a failure by one or more sub-LAGs.
15. The method according to claim 5 , wherein the egress interface data represents a subset of ports on the routing device, the subset of ports determining paths to a next hop having the next hop routing address.
16. The method according to claim 15 , further comprising querying the egress table to determine the subset of ports.
17. The method according to claim 15 , further comprising assigning at least one of the subset of ports using equal-cost multi-path (ECMP) hashing.
18. The method according to claim 15 , wherein using the egress interface data comprises, based on the sub-LAG ID, assigning at least one of the subset of ports to forward the packets to reach a LAG peer node.
19. The method according to claim 18 , wherein the LAG peer node is chosen as a next hop for a predetermined destination IP for the packets.
20. An information handling system to facilitate routing to the actual next hop comprising:
a plurality of input/output (I/O) ports, at least a portion of which are configurable to facilitate communications with one or more devices and configurable to be part of a link aggregation group (LAG);
one or more processors that are communicatively coupled to the plurality of I/O ports; and
a non-transitory memory comprising one or more sequences of instructions which, when executed by at least one of the one or more processors, causes steps to be performed comprising:
receiving, from a host, packets at a routing device in a path to an indented network node;
determining a next hop routing address from a route table stored in memory;
based on the next hop routing address, looking up in an Address Resolution Protocol (ARP) table an entry for an egress interface, the entry for the egress interface corresponding to a routing information;
determining from the entry an egress interface that is associated with a sub-LAG that has a sub-Lag ID and that identifies one or more ports communicatively coupled to one or more LAG peer nodes from a plurality of LAG peer nodes, the sub-LAG having been formed by using Link Layer Discovery Protocol (LLDP) information to group a set of links that connect to a unique LAG peer node; and
using the sub-LAG to send a packet to the intended network node, the sub-LAGs being associated with a parent LAG that has a parent LAG ID.