Hi Tobias,

> Hi Valery,
> 
> I agree that generally retransmits are not useful or needed with TCP
> encapsulation.  But as I see it, retransmits might actually be required
> in some situations.  If the client sends e.g. a CREATE_CHILD_SA request
> but the TCP connection is closed or gets unusable for some reason before
> the server's response is received, the client has to reestablish the TCP
> connection.  And the only way to do this (with window size 1, so no DPD
> or MOBIKE update can be sent) is to send a retransmit of the already
> sent message (otherwise the server might not know which TCP connection

That's why I suggested SHOULD :-)

> to use to send the CREATE_CHILD_SA response - I guess ESP packets could
> be used for that too, if there are any and there is a way to get
> notified in userland).  On the other hand, RFC 8229 explicitly says that
> a responder should not consider retransmitted messages when deciding
> which TCP connections should be used...so I guess there is no way to
> recover properly if the TCP connection is severed mid-exchange (e.g.
> because a NAT device is rebooted or the client device roams between
> networks).

Yes, there may be situations which are difficult to recover from...

Regards,
Valery.

> Regards,
> Tobias

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