US 9,792,106 B1Granted

Technique for fast network device configuration upgrade and reload

AssigneeCisco Technology, Inc.

InventorsRaja Kommula, Chickayya Naik, Naren Mididaddi, Francesco Meo, Sharanya Subramanian

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Abstract

A network device includes a control processor and a network processor unit (NPU) to forward network packets between network ports of the device. The processor downloads a new operating system (OS). The processor performs a fast upgrade to the new OS using a fast upgrade/reload technique to isolate the processor from interruptions and, without rebooting the processor, start the new OS in place of an existing OS. The fast upgrade/reload also includes delaying a reset of the NPU so that the NPU continues to route the network packets based on existing forwarding information. The fast upgrade/reload includes resetting the NPU only when the new OS first accesses the NPU, and then programming the reset NPU.

Claims23

Dependent claims

A method comprising:

at a processor of a network device having a network processor unit (NPU) coupled to the processor and to network ports of the network device, the NPU configured to forward network packets between the network ports using forwarding information accessible to the NPU:
while executing an existing operating system used to control the network device, downloading a new operating system with which to upgrade the existing operating system and update the NPU with new forwarding information from the new operating system;
before starting the new operating system, saving existing forwarding information associated with network switches connected to the network device;
disabling direct memory access transfers, access to the NPU, and interrupts with respect to the processor;
without rebooting the processor, overwriting the existing operating system with the new operating system and starting the new operating system in place of the existing operating system;
delaying a reset of the NPU while multiple new operating system processes are starting until after a first of the multiple new operating system processes requests to access the NPU so that the NPU continues to route the network packets based on existing forwarding information;
resetting the NPU after the first of the multiple new operating system processes requests to access the NPU;
and
after resetting the NPU:
programming the NPU with the new forwarding information;
identifying uplink ports of the network device based on the saved forwarding information and enabling the identified uplink ports;
and
programming the NPU with the saved forwarding information.

10 more elements

An apparatus comprising:

a plurality of ports to receive packets from a network and to output packets to the network;
a network processor unit (NPU) connected with the ports to forward the packets between the ports based on forwarding information accessible to the NPU;
a processor coupled with the NPU, wherein the processor is configured to:
while executing an existing operating system used to control the apparatus, download a new operating system with which to upgrade the existing operating system and update the NPU with new forwarding information from the new operating system;
before starting the new operating system, save existing forwarding information associated with network switches connected to the network device;
disable direct memory access transfers, NPU access, and processor interrupts;
without rebooting the processor, overwrite the existing operating system with the new operating system and start the new operating system in place of the existing operating system;
delay a reset of the NPU while multiple new operating system processes are starting until after a first of the multiple new operating system processes requests to access the NPU so that the NPU continues to route the network packets based on existing forwarding information;
reset the NPU after the first of the multiple new operating system processes requests to access the NPU;
and
after resetting the NPU:
program the NPU with the new forwarding information;
identify uplink ports of the network device based on the saved forwarding information and enable the identified uplink ports;
and
program the NPU with the saved forwarding information.

12 more elements

A non-transitory computer readable storage media encoded with instructions that, when executed by a processor of a network device that includes a network processor unit (NPU) configured to forward network packets between network ports of the network device using forwarding information accessible to the NPU, cause the processor to:

while executing an existing operating system used to control the network device, download a new operating system with which to upgrade the existing operating system and update the NPU with new forwarding information from the new operating system;
before starting the new operating system, save existing forwarding information associated with network switches connected to the network device;
disable direct memory access transfers, NPU access, and processor interrupts;
without rebooting the processor, overwrite the existing operating system with the new operating system and start the new operating system in place of the existing operating system;
delay a reset of the NPU while multiple new operating system processes are starting until after a first of the multiple new operating system processes requests to access the NPU so that the NPU continues to route the network packets based on existing forwarding information;
reset the NPU after the first of the multiple new operating system processes requests to access the NPU;
and
after resetting the NPU:
program the NPU with the new forwarding information;
identify uplink ports of the network device based on the saved forwarding information and enable the identified uplink ports;
and
program the NPU with the saved forwarding information.

9 more elements

Dependencies are inferred from the claim text.