Re: New Plaintext QUIC-LB Design

[Martin Duke <[e-mail]>]

Hi Mikkel,

Answers inline

On Mon, Jan 11, 2021 at 3:19 PM Mikkel Fahnøe Jørgensen <[e-mail]>
wrote:

> I’m trying to read through the LB document that I haven’t looked at for
> quite a while. It isn’t very clear to me, I am sorry to say.
>
> I do not understand why the highest configuration value is chosen since
> this value would eventually wrap? Is there an implied wider config value
> where only the lower bits are visible, similar to packet numbers?
>

In general, client-generated CIDs might come in with config rotation bits
that don't correspond to an existing config. For the other algorithms, it's
randomly routed and after that the server-generated CID is used. But for
this algorithm, the server needs to extract a server ID somehow. If there's
one configuration, that's simple. If there's more than one, there has to be
deterministic behavior. The choice to use the highest is completely
arbitrary; I'm open to other suggestions that have better properties.


> Also, I do not understand how the server receives the assigned SID. Is the
> ODCID replaced in first packets, or are the packets unmodified, or is the
> SID prefixed the real packet?
>

No, any 8-byte CID will contain a server ID. So the client, in effect,
generates an SID and the load balancer decides which server will get it
(and then use that SID in the future)


> If the ODCID is modified, what about message authentication, also in
> future versions and with possible shared keys?
>

It is not modified, see above

Is the state table affected by the clients choice of ODCID (think abuse)?
>

Yes, if CIDs are chosen to maximize the number of different SIDs, that will
grow the table. IMO this isn't substantially different from randomly chosen
CIDs, which is of course normal behavior.