Methods and systems for hitless restart of layer 3 packet forwarding

A system for hitless failure of layer 3 forwarding in response to failure of a management service module, the system comprising:

• (a) a master management service module for participating in layer 3 routing protocols to build a first layer 3 routing table and storing the first layer 3 routing table in memory, for building a first layer 3 forwarding table based on received packets and lookups in the first layer 3 routing table, and for replicating the first layer 3 forwarding table to a plurality of input/output modules for forwarding packets;
• (b) a plurality of inpuvoutput modules for forwarding packets using the first layer 3 routing and forwarding tables;
• and
• (c) a slave management service module for storing a copy of the first layer 3 forwarding table, detecting failure of the master management service module, and, in response, building a second layer 3 routing table by participating in layer 3 routing protocols, anu for linking entries in the second layer 3 routing table with entries in the copy of the first layer 3 forwarding table.

A computer program product comprising computer-executable instructions embodied in a computer-readable medium for performing steps comprising:

• (a) receiving a copy of a layer 3 packet forwarding table from a master management service module;
• (b) detecting failure of the master management service module;
• (c) in response to step (b), initiating participation in layer 3 routing protocols;
• (d) building a layer 3 routing table based on step (c);
• and
• (e) linking entries in the layer 3 routing table to entries in the layer 3 forwarding table.