IETF-55

IMPP routing and SMTP timely delivery

Discuss IMPP routing and SMTP timely with Dave Crocker

Dave will write up IMPP SRV routing based on my notes, and pass by me:

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Note we have the original URI to play with (though, we may have to assume that this is conveyed intact by the specific IM protocols, or can be reconstructed from the protocol-specific addresses.

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Scenario

I am _apex

Target domain is _simple

Both can gateway _xmpp

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Lookup

  _im._in.targetdomain

Return

  _im._simple.nativetargetdomain   pref 0

  _im._xmpp.gatewaytargetdomain    pref 10

To send using simple, use "gatewaytargetdomain" per simple rules.

To send using xmpp, use "gatewaytargetdomain" per xmpp rules.

.....

Lookup

  _im._out.localdomain

Return

  _im._apex.nativelocaldomain   pref 0

  _apex._xmpp.gatewaylocaldomain  pref 20

.....

Sender determines that overlap is xmpp, so sends using apex to gatewaylocaldomain.

gatewaylocaldomain repeats lookup in targetdomain, and sends xmpp to gatewaytargetdomain.

gatewaytargetdomain repeats lookup and sends simple to end user.

All this presumes that the individual IM protocols that don't depend on relays, or have multiple relays, have their own private mechanisms to ensure the foreign traffic is appropriately routed.  E.g. when the simple message gets to "nativetargetdomain" it will be delivered to the host appropriate to the addressee.  Until then, it gets sent to relays determined by the protocol in use.

[I'm still slightly uneasy about this  maybe need to be more explicit about assumed routing properties of IM protocols.]

Spotted it!

Assume all native IM adresses are of the form <localpart,domain>.  When an SRV record cites a target domain for a foreign protocol, how is the localpart mapped into that domain.  Answer  use the original im URI ad let the protocol figure it out.  I think that works.