Abstract: In one embodiment, a packet switching device creates multiple virtual packet switching devices within the same physical packet switching device using virtual machines and sharing particular physical resources of the packet switching device. One embodiment uses this functionality to change the operating version (e.g., upgrade or downgrade) of the packet switching device by originally operating according to a first operating version, operating according to both a first and second operating version, and then ceasing operating according to the first operating version. Using such a technique, a packet switching device can be upgraded or downgraded while fully operating (e.g., without having to reboot line cards and route processing engines).

Abstract: In one embodiment, a packet switching device creates multiple virtual packet switching devices within the same physical packet switching device using virtual machines and sharing particular physical resources of the packet switching device. One embodiment uses this functionality to change the operating version (e.g., upgrade or downgrade) of the packet switching device by originally operating according to a first operating version, operating according to both a first and second operating version, and then ceasing operating according to the first operating version. Using such a technique, a packet switching device can be upgraded or downgraded while fully operating (e.g., without having to reboot line cards and route processing engines).

Abstract: In one embodiment, a packet switching device creates multiple virtual packet switching devices within the same physical packet switching device using virtual machines and sharing particular physical resources of the packet switching device. One embodiment uses this functionality to change the operating version (e.g., upgrade or downgrade) of the packet switching device by originally operating according to a first operating version, operating according to both a first and second operating version, and then ceasing operating according to the first operating version. Using such a technique, a packet switching device can be upgraded or downgraded while fully operating (e.g., without having to reboot line cards and route processing engines).

Abstract: A software reload is executed. The hardware associated with the network device continues to forward network traffic during the software reload. Also, a kernel of the network device operates unaffected in a protected address space throughout the software reload. Further, the kernel preserves local checkpointed and shared memory data. Application processes running on the network node are shut down gracefully. The reloaded software is brought up and the network device is resynchronized.

Abstract: In one embodiment, a packet switching device creates multiple virtual packet switching devices within the same physical packet switching device using virtual machines and sharing particular physical resources of the packet switching device. One embodiment uses this functionality to change the operating version (e.g., upgrade or downgrade) of the packet switching device by originally operating according to a first operating version, operating according to both a first and second operating version, and then ceasing operating according to the first operating version. Using such a technique, a packet switching device can be upgraded or downgraded while fully operating (e.g., without having to reboot line cards and route processing engines).

Abstract: A software reload is executed. The hardware associated with the network device continues to forward network traffic during the software reload. Also, a kernel of the network device operates unaffected in a protected address space throughout the software reload. Further, the kernel preserves local checkpointed and shared memory data. Application processes running on the network node are shut down gracefully. The reloaded software is brought up and the network device is resynchronized.

Abstract: Methods and apparatus are disclosed for dynamic allocation and management of semaphores for accessing shared resources. In one implementation, a semaphore manager maintains a data structure of resources having currently active resource requests and a list of each task requesting access and the particular type of access requested. When an access request is received for the first time for a resource, an entry is added to the data structure and access is authorized. Additional requests to access the resource may be received while the resource is allocated. If a new request for read access is received and the resource is currently under read access, access is granted and an entry is added to the data structure. Otherwise, the resource is currently unavailable, and access is either immediately denied or queued for possible future allowance during a specified, predetermined or forever duration.