Patent ID: 8499060

Claim:
A method performed by a network device, the method comprising: receiving, by the network device, an upgrade package, the network device operating as one of a modular chassis or a virtual chassis that corresponds to a single logical network device; sending, by a master routing component of the network device, the upgrade package to a backup routing component of the network device; preparing, by the network device, multiple line cards for a software upgrade, ports, in each line card of the multiple line cards, being part of a link aggregation group (LAG); determining, by the network device, a subset of the multiple line cards on which to perform the software upgrade; initiating, by the network device, a reboot process for the subset of the multiple line cards, the reboot process resulting in a software upgrade for each line card, of the subset of the multiple line cards; repeating the determining and the initiating until each line card, in the multiple line cards, is upgraded; and switching, by the network device and based on each line card of the multiple line cards being upgraded, the role of the backup routing component and the role of the master routing component to designate another master routing component and another backup routing component.