Method and system for minimizing disruption during in-service software upgrade

摘要

A method and a system for in-service software upgrade in a Hot Standby Redundant Distributed (HSRD) system are provided. A standby route processor in HSRD system is updated with upgraded software. The standby route processor is synchronized with an active route processor present in the HSRD system. The control of routing process is switched over to the standby route processor (with the upgraded software) from the active route processor. During the switchover, a minimal context forwarder on the line card begins execution and continues forwarding packets across a network, while a line card in the HSRD system is being reloaded and configured.

主权项

1. A method comprising:
enabling a first route processor to operate in an active mode and a second route processor to operate in a standby mode, wherein the first route processor operating in the active mode controls a routing process involving one or more line cards forwarding packets in a network and the second route processor operating in the standby mode does not control the routing process; receiving a modified system software at the second route processor operating in the standby mode, wherein the modified system software is an upgrade or downgrade of software on the second route processor; in response to receiving the modified system software, downloading a minimal context forwarder from the second route processor operating in the standby mode into one of the one or more line cards that is forwarding packets, the minimal context forwarder derived from the modified system software received at the second route processor and includes a subset of functionality of the modified system software; initiating operation of the minimal context forwarder in the one or more line cards, wherein the minimal context forwarder in each of the one or more line cards controls operation of the one or more line cards respectively to continue forwarding the packets while the minimal context forwarder in each of the one or more line cards is reloading the one or more line cards with the modified system software received from the second route processor; forwarding packets received at the one of the one or more line cards using the minimal context forwarder that is downloaded into the one of the one or more line cards; reloading, by the minimal context forwarder that is downloaded into the one of the one or more line cards, the one of the one or more line cards with the modified system software received from the second route processor operating in the standby mode; and updating system software associated with the one of the one or more line cards with the modified system software while the minimal context forwarder that is downloaded into the one of the one or more line cards is forwarding packets.