Method and apparatus for establishing adjacency for a restarting router during convergence

A method of re-establishing adjacency in an inter-networked system, the method comprising:

• i) determining that adjacency establishment is required;
• ii) transmitting a message to discover neighboring network elements;
• iii) receiving one or more messages from neighboring network elements;
• and
• iv) in response to the one or more received messages, generating a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• v) sending the first link-state packet;
• vi) interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• vii) on convergence of a forward cache, sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit set that is not set.

A computer-readable storage medium storing one or more sequences of instructions for establishing adjacencies on a network, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:

• sending one or more hello packets on the network;
• receiving one or more hello packets from other nodes on the network on the basis of the sent hello packets;
• in response to receiving the one or more hello packets, sending a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• on convergence of a forward cache, sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit that is not set.

A computer-readable storage medium storing one or more sequences of instructions for re-establishing adjacency in an inter-networked system, which instructions, when executed by one or more processors, cause the one or more processors to carry out the steps of:

• i) determining that adjacency establishment is required;
• ii) transmitting a message to discover neighboring network elements;
• iii) receiving one or more messages from neighboring network elements;
• and
• iv) in response to the one or more received messages, generating a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• v) sending the first link-state packet;
• vi) interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• vii) on convergence of a forward cache, sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit set that is not set.

Apparatus for establishing adjacencies on a network, the apparatus comprising:

• means for sending one or more hello packets on the network;
• means for receiving one or more hello packets from other nodes on the network on the basis of the sent hello packets;
• means for, in response to receiving the one or more hello packets, sending a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• means for interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• on convergence of a forward cache, means for sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit that is not set.

Apparatus for re-establishing adjacency in an inter-networked system, the apparatus comprising:

• i) means for determining that adjacency establishment is required;
• ii) means for transmitting a message to discover neighboring network elements;
• iii) means for receiving one or more messages from neighboring network elements;
• and
• iv) means for in response to the one or more received messages, generating a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• v) means for sending the first link-state packet;
• vi) means for interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• vii) on convergence of a forward cache, means for sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit set that is not set.

An apparatus for establishing adjacencies on a network, the apparatus comprising:

• a network interface that is coupled to the network for receiving one or more packet flows therefrom;
• a processor;
• one or more stored sequences of instructions which, when executed by the processor, cause the processor to carry out the steps of:
• sending one or more hello packets on the network;
• receiving one or more hello packets from other nodes on the network on the basis of the sent hello packets;
• in response to receiving the one or more hello packets, sending a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• on convergence of a forward cache, sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit that is not set.

An apparatus for re-establishing adjacency in an inter-networked system, the apparatus comprising:

• a network interface that is coupled to the network for receiving one or more packet flows therefrom;
• a processor;
• one or more stored sequences of instructions which, when executed by the processor, cause the processor to carry out the steps of:
• i) determining that adjacency establishment is required;
• ii) transmitting a message to discover neighboring network elements;
• iii) receiving one or more messages from neighboring network elements;
• and
• iv) in response to the one or more received messages, generating a first link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the first link-state packet includes a field for an overload bit;
• wherein the overload bit in said field is not set;
• wherein the first link-state packet comprises no adjacency information;
• v) sending the first link-state packet;
• vi) interrogating a link-state adjacency table and, when only one adjacency is listed in the link-state table, sending a second link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the second link-state packet comprises adjacency information and an overload bit that is set;
• and
• vii) on convergence of a forward cache, sending a further link-state packet in Intermediate System-to-Intermediate System protocol;
• wherein the further link-state packet comprises adjacency information and an overload bit set that is not set.