Re: [Int-area] [EXTERNAL] Re: Call for WG adoption of draft-templin-intarea-parcels-10

["Robinson, Herbie" <[e-mail]>]

Fred Templin Wrote:
> Tom:
>>The algorithm isn't the problem, it's supporting new protocols and multiple
>>checksums in a packet in hardware.

>But Tom, how hard can this be? Instead of running the Internet checksum 1 time
>over N octets of data simply run it M times over N/M octet chunks of the data in
>succession but still in a single pass. You spoke before of NICs adapting to support
>TCP jumbograms – if they can do that, why not a very straightforward application
>of Internet checksum? I haven’t looked at this in a long while, but isn’t this also
>similar to what UDP-lite did?

The various hardware adapters that I am familiar with (most of Intel’s high end line) use a fixed sized ring buffer with a fixed sized slot for each packet received.  They are already restricting the use of all features at the same time because they don’t have enough bits in the per packet slot.  They certainly have no way to deal with reporting success or failure of an unbounded number of checksum computations in a fixed sized slot.