Hi Tom, It looks like you're using 1's complement math, so you may find this helpful: https://tools.ietf.org/html/rfc1624
Anoop On Tue, Dec 2, 2014 at 9:47 AM, Tom Herbert <[email protected]> wrote: > This is a proposal for remote checksum offload in VXLAN. We use a > compressed format for the remote checksum offload data to support > offload of UDP and TCP inner checksums. This allocates a reserved bit > (#10 which would be immediately after version bits in VXLAN-GPE) and > uses the 8 bits after VNI for data. > > I have implemented this in Linux stack and posted a first cut on > netdev (http://permalink.gmane.org/gmane.linux.network/339847). It > works as expected, eliminating the need to perform host checksum > computation over a packet when encapsulating TCP over VXLAN between > hosts using plain NICs. In simple throughput tests this reduced CPU > usage by ~20% on transmit, and using outer UDP checksum reduces CPU on > receive by almost 50%. > > Comments are appreciated. > > Thanks, > Tom > > > ---------- Forwarded message ---------- > From: <[email protected]> > Date: Tue, Dec 2, 2014 at 8:13 AM > Subject: New Version Notification for draft-herbert-vxlan-rco-00.txt > To: Tom Herbert <[email protected]> > > > > A new version of I-D, draft-herbert-vxlan-rco-00.txt > has been successfully submitted by Tom Herbert and posted to the > IETF repository. > > Name: draft-herbert-vxlan-rco > Revision: 00 > Title: Remote checksum offload for VXLAN > Document date: 2014-12-01 > Group: Individual Submission > Pages: 6 > URL: > http://www.ietf.org/internet-drafts/draft-herbert-vxlan-rco-00.txt > Status: https://datatracker.ietf.org/doc/draft-herbert-vxlan-rco/ > Htmlized: http://tools.ietf.org/html/draft-herbert-vxlan-rco-00 > > > Abstract: > This specification describes remote checksum offload for VXLAN. > Remote checksum offload is a mechanism that provides checksum offload > of transport checksums in encapsulated packets using rudimentary > offload capabilities found in most Network Interface Card (NIC) > devices. The outer UDP checksum is enabled on transmit and, with some > additional meta data, a receiver is able to deduce the checksum to be > set in an encapsulated packet. Effectively this offloads the > computation of the inner checksum which can be a significant > performance optimization. Enabling the UDP checksum has the > additional advantage that it covers more of the packet including the > IP pseudo header and virtual network identifier. > > > > > > Please note that it may take a couple of minutes from the time of > submission > until the htmlized version and diff are available at tools.ietf.org. > > The IETF Secretariat > > _______________________________________________ > nvo3 mailing list > [email protected] > https://www.ietf.org/mailman/listinfo/nvo3 >
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