Active IP forwarding in an event driven virtual link aggregation (vLAG) system

1. A method for managing virtual link aggregation (vLAG), the method comprising:

coupling a first networking switch with a second networking switch using an interswitch link (ISL), wherein the first networking switch is positioned at a boundary between Layer-2 (L2) and Layer-3 (L3), and wherein the second networking switch is positioned at the boundary between L2 and L3;

creating a virtual link aggregation (vLAG) comprising connections between the first and second networking switches and an access switch in L2, wherein each networking switch comprises a virtual router redundancy protocol (VRRP) module;

interacting and modifying a VRRP state machine to perform active internet protocol (IP) forwarding when a connection between one of the networking switches and the access switch fails or one of the networking switches does not function properly;

indicating status using each of the VRRP modules of their respective switch associated with VRRP via the ISL, wherein the statuses comprise: initialization when a switch is not currently active (INIT), back-up status (BACK-UP), and master status (MASTER); and

using each of the first and second networking switches: when a transition from the INIT state to a local switch active (LOCAL-UP) state is detected and when a virtual router instance over the vLAG has the BACK-UP status, setting up active IP forwarding such that any address resolution protocol (ARP) requests are responded to.

2. The method as recited in claim 1 , further comprising indicating state events using each of the first and second networking switches associated with the vLAG via the ISL, wherein the state events comprise: initialization (INIT), local switch active (LOCAL-UP), remote switch active (REMOTE-UP), and both switches active (FORMED).

3. The method as recited in claim 1 , further comprising, using each of the first and second networking switches:

when a transition from the LOCAL-UP state to a both switches active (FORMED) state is detected, synchronizing ARP entries learnt over the vLAG with a vLAG peer switch;

when a transition from a remote switch active (REMOTE-UP) state to the FORMED state is detected, and when a virtual router instance over the vLAG has the BACK-UP status, setting up active IP forwarding such that any ARP requests are responded to; and

when a transition from the LOCAL-UP state or the FORMED state to the INIT state is detected, and when a virtual router instance over the vLAG has the BACK-UP status, all settings made for performing active IP forwarding are reset.

4. The method as recited in claim 1 , further comprising, using each of the first and second networking switches:

when a transition from the BACK-UP status to the INIT status is detected, and when a networking switch in the vLAG indicates the LOCAL-UP state or a both switches active (FORMED) state, all settings made for performing active IP forwarding are reset;

when a transition from the INIT status to the BACK-UP status is detected, and when a networking switch in the vLAG indicates the LOCAL-UP state or the FORMED state, setting up active IP forwarding such that any address resolution protocol (ARP) requests are responded to;

when a transition from the INIT status to the BACK-UP status is detected, and when a networking switch in the vLAG indicates the LOCAL-UP state or the FORMED state, setting up active IP forwarding such that any address resolution protocol (ARP) requests are responded to and sending a request to synchronize all ARP entries learnt over the vLAG with a vLAG peer switch;

when a transition from the MASTER status to the BACK-UP status is detected, and when a networking switch in the vLAG indicates the LOCAL-UP state or the FORMED state, preserving any programmed active IP forwarding logic; and

when a transition from the BACK-UP status to the MASTER status is detected, and when a networking switch in the vLAG indicates the LOCAL-UP state or the FORMED state, preserving any programmed active IP forwarding logic.