On Mon, Oct 27, 2025 at 1:02 PM Mohit Sahni <[email protected]>
wrote:

> Hi Eric,
> One concern regarding using HTTP Alt Svc is that this limits the solution
> to HTTP based application, however TLS based solution helps with other
> application protocols too e.g. FTP or SMTP or any other protocol that uses
> STARTTLS construct.
>

Yes, I'm aware of that. However, for the reasons Indicated in my response
upstream, I think it's a feature that it happen at the application layer in
a protocol-specific fashion.

-Ekr


> -Mohit
>
> On Sun, Oct 26, 2025 at 7:55 PM Aijun Wang <[email protected]>
> wrote:
>
>> Hi, Eric:
>>
>> Thanks for your comments.
>> Your understanding of the overall procedure for this proposal is correct.
>>
>> But, as indicated by Usama and replied by Mohit, the detail procedures in
>> Figure 2 of this document should be based on TLS 1.3
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_html_rfc8446-23section-2D2&d=DwIFaQ&c=V9IgWpI5PvzTw83UyHGVSoW3Uc1MFWe5J8PTfkrzVSo&r=J7DgfMyeL26OZuy8d3qTy_h24Ff1NatxSKMgDUj2Kxg&m=S278vH9k736nF13K7hekoC9UmWiLbx5bPpySG6AG0wl-GJWmZBEH76RXKh178Prx&s=B0_YVjIgvDRP9AWMrgVcHGU594aeWIXGEZAZqvD8Liw&e=
>> If there is any misunderstanding due to the above ignorance, let's
>> discuss further based on our future update based on TLS 1.3
>>
>> Anyway, I try to explain our considerations in more detail inline below.
>>
>> Best Regards
>>
>> Aijun Wang
>> China Telecom
>>
>> -----Original Message-----
>> From: [email protected] [mailto:[email protected]]
>> On Behalf Of 【外部账号】 Eric Rescorla
>> Sent: Saturday, October 25, 2025 1:24 AM
>> To: Aijun Wang <[email protected]>
>> Cc: [email protected]; [email protected]
>> Subject: Re: [TLS] FW: New Version Notification for
>> draft-wang-tls-service-affinity-00.txt
>>
>> Document: draft-wang-tls-service-affinity-00.txt
>>
>> I'm a little confused about the requirements driving this design.
>>
>> At a high level, it seems to me that you have the following set of
>> events:
>>
>> 1. The client connects to the server using TLS via an anycast address
>>    A1.
>> 2. The server tells the client that it can/should be reached
>>    at a new non-anycast address A2.
>> 3. The client reconnects to the server at A2.
>> 【WAJ】Yes
>>
>> I would make several points.
>>
>> First, the mechanism you propose seems heavyweight for this purpose.
>> In particular, I don't understand why you need any authentication at all
>> for the new address indication (the MigrationToken) because the client is
>> going to authenticate to the server via normal TLS mechanisms. Recall that
>> TLS is designed for a Dolev-Yao style attacker and doesn't trust the
>> network at all, including the binding of DNS name to IP address; even if
>> the client were provided with a completely false IP address for the server
>> this would not allow impersonation of the server.
>> 【WAJ】The "Migration_Token" is manly used to bind the new connection to
>> the previous session.
>>
>> Second, I don't understand why you need the server to validate the
>> MigrationToken. What properties are being bound to this token? It seems
>> better to just bind whatever properties those are into the session ticket
>> and treat this as a new connection.
>> 【WAJ】The main properties in "Migration_Token" is the session_id, which
>> can be used to lookup the previous negotiated PSK. Such design can
>> eradicate the new PSK negotiation procedure.
>>
>> Third, I'm skeptical that the TLS layer is the right place to do this
>> kind of migration, because you have race conditions where one side
>> initiates a migration and the other side has outstanding data which will
>> never be processed. These kinds of issues need to be resolved at the
>> application layer, which is also a more convenient layer to initiate
>> migration.
>> 【WAJ】The initial purpose is to switch the address ASAP. There may be some
>> race conditions(would you like to illustrate some?) and extra signal may be
>> necessary later to refine the switchover.
>>
>> Overall, ISTM that a better design would be to just use something like
>> HTTP Alt-Svc to steer the client to a different address, rather than doing
>> this at the TLS layer. If you disagree, I think it would be helpful to
>> explain the requirements that lead to this design.
>> 【WAJ】Before proposing the switchover at TLS layer, we have analyzed the
>> other possible solutions, for example, via application load balance, http
>> redirection and DNS redirection(please review
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_html_draft-2Dwang-2Dtls-2Dservice-2Daffinity-2D00-23name-2Dintroduction&d=DwIFaQ&c=V9IgWpI5PvzTw83UyHGVSoW3Uc1MFWe5J8PTfkrzVSo&r=J7DgfMyeL26OZuy8d3qTy_h24Ff1NatxSKMgDUj2Kxg&m=S278vH9k736nF13K7hekoC9UmWiLbx5bPpySG6AG0wl-GJWmZBEH76RXKh178Prx&s=wjYYFdlQkm_hyIPH5wlCSjErLDcYyWrJ_FkapLN_7k0&e=
>> ).
>>    The reason that we propose the switchover at TLS layer, due to the
>> optimization selection decision is made at the network itself(together with
>> the availability of server resource), not at the application layer. The
>> application is difficult to know which is the best server that can match
>> the client's QoS requirements.(we call it the combination optimization
>> process, which is the goal of the CATS WG).
>>     And, actually, QUIC has also such migration process:
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__datatracker.ietf.org_doc_html_rfc9000-23name-2Dconnection-2Dmigration&d=DwIFaQ&c=V9IgWpI5PvzTw83UyHGVSoW3Uc1MFWe5J8PTfkrzVSo&r=J7DgfMyeL26OZuy8d3qTy_h24Ff1NatxSKMgDUj2Kxg&m=S278vH9k736nF13K7hekoC9UmWiLbx5bPpySG6AG0wl-GJWmZBEH76RXKh178Prx&s=IhoM_hlC_ptCYdMMOa72ZAogUt3qS7ywnXCGgH8gpWA&e=
>>
>>
>> -Ekr
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> On Tue, Oct 21, 2025 at 2:10 AM Aijun Wang <[email protected]>
>> wrote:
>>
>> > Hi, All:
>> >
>> > We have submitted one new draft regarding to the service affinity
>> > function for TLS based application.
>> > We are also applying the time slot for the presentation on the coming
>> > IETF
>> > 124 meeting.
>> >
>> > Wish to get your comments/suggestions on this topic before the
>> > meeting, and we can also discuss further during the on-site meeting.
>> >
>> > Best Regards
>> >
>> > Aijun Wang
>> > China Telecom
>> >
>> > -----Original Message-----
>> > From: [email protected] [mailto:[email protected]]
>> > Sent: Friday, October 17, 2025 4:34 PM
>> > To: Aijun Wang <[email protected]>; Ketul Sheth <
>> > [email protected]>; Mohit Sahni
>> > <[email protected]>; Wei Wang <[email protected]>
>> > Subject: New Version Notification for
>> > draft-wang-tls-service-affinity-00.txt
>> >
>> > A new version of Internet-Draft draft-wang-tls-service-affinity-00.txt
>> > has been successfully submitted by Wei Wang and posted to the IETF
>> repository=
>>
>>
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