Methods and apparatus for avoiding inter-chassis redundancy switchover to non-functional standby nodes

A standby inter-chassis redundancy, ICR, node for routing messages in a communications system, the standby ICR node comprising:

• at least one network interface configured to communicate messages with an active ICR node and a plurality of other network nodes;
• and
• a microprocessor connected to the at least one network interface to send and receive messages, and configured to:
• detect occurrence of a standby failure event that indicates that the standby ICR node has become or will become at least partially non-functional as a backup message router for the active ICR node;
• control the active ICR node to transition from operation in an active-with-peer state to operation in an active-without-peer state in response to the standby failure event, the active ICR node being configured to not switchover routing responsibility to the standby ICR node and maintain its routing responsibility when the active ICR node is in the active-without-peer state;
• and
• perform a switchover to take at least part of the message routing responsibility from the active ICR node when a switchover triggering event occurs at the active ICR node while the active ICR node is operating in the active-with-peer state.

A method of providing inter-chassis redundancy, ICR, for message routing in a communication system using a standby ICR node that functions as a backup message router for an active ICR node, the method comprising:

• performing a switchover operation for the standby ICR node to take over at least part of the message routing responsibility from the active ICR node when a switchover triggering event occurs at the active ICR node while the active ICR node is operating in an active-with-peer state;
• detecting occurrence of a standby failure event that indicates that the standby ICR node has become or will become at least partially non-functional as a backup message router for the active ICR node;
• and
• controlling the active ICR node to transition from operation in the active-with-peer state to operation in an active-without-peer state in response to the standby failure event, wherein when operating in the active-without-peer state the standby ICR node does not perform the switchover operation and the active ICR node maintains its routing responsibility.