Inter-chassis redundancy with coordinated traffic direction

摘要

A method, in a first network element of an inter-chassis redundancy (ICR) system, of cooperating with a second network element of the ICR system to provide ICR. The network elements are coupled by a synchronization channel. IP addresses are announced with a favorable traffic direction attribute. It is determined that the second network element either has announced the IP addresses with an unfavorable traffic direction attribute less favorable than the favorable direction attribute, or has not announced the IP addresses. Sessions that are connected through the IP addresses are handled. Session state synchronization messages that include session state for the handled sessions are transmitted over the synchronization channel to the second network element. It is determined, after an occurrence of a failure event that inhibits the first element from handling the sessions, that the IP addresses have been announced by the second network element with a favorable traffic direction attribute.

主权项

1. A method performed by a first network element of an inter-chassis redundancy (ICR) system, the first network element coupled with a second network element of the ICR system by a synchronization channel, of cooperating with the second network element to provide ICR, said method comprising the steps of:
announcing a set of Internet Protocol (IP) addresses with a favorable traffic direction attribute, wherein said announcing the set of IP addresses with the favorable traffic direction attribute comprises announcing the set of IP addresses with a preferred active traffic direction attribute; determining that one of: (a) the second network element has announced the set of IP addresses with an unfavorable traffic direction attribute that is less favorable than the favorable traffic direction attribute; and (b) the second network element has not announced the set of IP addresses; after determining that either the second network element has announced the set of IP addresses with the unfavorable traffic direction attribute or the second network element has not announced the set of IP addresses, announcing the set of IP addresses with an active traffic direction attribute, wherein the active traffic direction attribute is more favorable than the preferred active traffic direction attribute; handling sessions that are connected through the set of IP addresses; transmitting session state synchronization messages over the synchronization channel to the second network element, wherein the session state synchronization messages include session state for the handled sessions; and determining, after an occurrence of a failure event that inhibits the first network element from handling the sessions, that the set of IP addresses have been announced by the second network element with the favorable traffic direction attribute.