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Efficient checksum in overlay networks Disclosure Number: IPCOM000237201D
Publication Date: 2014-Jun-08
Document File: 2 page(s) / 24K

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The Prior Art Database


A method for efficient checksum calculation in overlay networks is disclosed.

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Efficient checksum in overlay networks

Disclosed is a method for efficient checksum calculation in overlay networks.

Overlay networks such as Distributed Overlay Virtual Ethernet (DOVE) encapsulate the data packet in a User Datagram Protocol (UDP) packet. This method of encapsulation causes the checksum to be done in the host instead of using the network interface controller (NIC) off-load.

NIC off-load exist but the checksum is done only for *one* layer of TCP/UDP or IP message. The disclosed method provides an extension to existing NICs, without any hardware changes, to provide efficient checksum when TCP/IP packets are encapsulated in UDP/TCP packets.

The checksum is a 1's complement sum of bytes that are then inserted into a specific field of the TCP/UDP packet. There is also an IPv4 header checksum but that is over a small set of bytes and so not as significant as the payload checksum needed for TCP/UDP. In most of the modern NICs the checksum is done in hardware saving a lot of CPU overhead in the server.

Currently, in a DOVE implementation, an overlay or tunnel based network is setup where the packet is: IP->UDP->IP->TCP->data

The NIC can do checksum of either the inner or the outer header. If it does the outer header checksum, the inner checksum still needs to be done in the server. If it does the inner checksum, the outer checksum has to be inserted somehow.

The expectation is that the NIC vendors are extending their implementations to augment such tunn...