N-node virtual link trunking (VLT) systems fault management

A method for handing a failure of an inter-node link (INL) of a virtual link trunking (VLT) group in a n-node VLT system that comprises a plurality of nodes communicatively coupled via inter-node links (INLs) and at least some of the plurality of nodes of the n-node VLT system being communicatively coupled via one or more input/output (I/O) ports to one or more client devices to form one or more VLTs, the method comprising:

• responsive to detecting an INL failure between a first node and a second node in the n-node VLT system:
• selecting one of the first and second nodes to be removed from the n-node VLT system based upon one or more criteria;
• disabling VLT ports at the node that is to be removed from the n-node VLT system according to rules comprising:
• responsive to a VLT having as its only member the node that is to be removed from the n-node VLT system, retaining that VLT at that node;
• and
• responsive to a VLT having more node members including the node that is to be removed from the n-node VLT system, disabling that VLT at the node that is to be removed from the n-node VLT system;
• disabling all INL ports, except one, at the node that is to be removed from the n-node VLT system, the one INL port that is retained being selected based upon one or more criteria;
• and
• removing the selected node from the n-node VLT system in order to operate, based upon table programming, including port block mask, as a normal switch connected to one of the nodes in the n-node VLT system.

A method for handing a failure of a node in a n-node virtual link trunking (VLT) system that comprises a plurality of nodes communicatively coupled via inter-node links (INLs) and at least some of the plurality of nodes of the n-node VLT system being communicatively coupled via one or more input/output (I/O) ports to one or more client devices to form one or more VLTs, the method comprising:

• responsive to a node failure being detected:
• assigning one of the remaining nodes in the n-node VLT system as a topology-change-owner node, the topology-change-owner node performing the steps comprising:
• determining one or more topology tables entries that require ownership change;
• and
• sending one or more messages to one or more nodes in the n-node VLT system to assume ownership for a certain table entry or entries;
• computing assigned nodes for the remaining nodes in the n-node VLT system, an assigned node being a node in the n-node VLT system has an active link or links for a VLT, wherein data traffic that is intended for the VLT and received at the first node is sent via an INL to the assigned node for egress;
• updating one or more port block masks for the n-node VLT system to avoid loops;
• and
• synchronizing topology tables entry or entries that have changed as a result of the node failure to maintain a consistent representation across the remaining nodes in the n-node VLT system.