Re: Can I set the UDP checksum to zero when running QUIC?

[Christian Huitema <[e-mail]>]

One the other hand, the cost of computing the checksum is tiny compared 
to the cost of encrypting the packets. So there is a small performance 
gain in not computing the checksum, compensate by the potential gain of 
loosing compatibility.

If I were to do that, I would do some trials. Until the handshake is 
complete, use the checksum. Then, send a trial packet with null 
checksum. If the peer acknowledges it, then further packets can be sent 
with null checksum. Redo the trial for each new path, or if there are 
large number of packet losses. Basically, treat that the same way we do 
PMTUD.

-- Christian Huitema

On 3/12/2024 3:57 PM, Martin Thomson wrote:
> The question is more of a compatibility one than anything else.  What, if anything breaks if you do this?
> 
> As noted, there are contexts in which not computing the checksum works.  So I guess the conclusion is that nothing breaks, so go ahead.  QUIC doesn't depend on the checksum.  All the cryptographic bits of QUIC use far stronger and more reliable mechanisms.
> 
> On Tue, Mar 12, 2024, at 22:04, Shihang(Vincent) wrote:
>> Hi QUIC wg,
>> Since QUIC has strong encryption and integrity protection provided by
>> TLS 1.3. I wonder if the UDP checksum can be disabled(using UDP Zero
>> Checksum Mode https://www.rfc-editor.org/rfc/rfc6936 )to save the
>> computation just like in VXLAN(RFC7348
>> <https://datatracker.ietf.org/doc/html/rfc7348#autoid-12>).
>>
>> Thanks,
>> Hang
>