Subject: [AAA-WG]: Issue 24: Transport Selection

From: Pat Calhoun <[email-masked]>
Date: Tue, 5 Jun 2001 16:09:37 -0700

All,

This one was previously owned by Bernard, but we have no issue on it, so I've taken it
over, below, and am proposing text to close this one.

PatC
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Issue 24: Transport Selection 
Submitter name: Pat Calhoun 
Submitter email address: [email-masked] 
Date first submitted: 2001-06-05 
Reference: 
Document: Base 
Comment type: C 
Priority: 1 
Section: 2.1 
Rationale/Explanation of issue: 

At the Interim Meeting, Bernard stated that the base protocol should 
describe how to connect to a peer in the case where more than one 
transport is available, or the transport wasn't specified. 

Requested change: 

Add the following text to the end of section 2.1: 
    When connecting to a peer, and either zero or more transports are 
    specified, SCTP SHOULD be tried first (if supported), followed by TCP.
    Diameter implementations SHOULD be able to interpret explicit network 
    notifications (such as ICMP messages) which indicate that a server is 
    not reachable, rather than relying solely on timeouts (e.g. connect() 
    returns ECONNREFUSED if the client could not connect to a server at 
    that address).

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From: Allison Mankin <[email-masked]>
Date: Tue, 05 Jun 2001 23:58:10 -0400

Pat,

>     specified, SCTP SHOULD be tried first (if supported), followed by TCP.

It'd be useful also to point to the sections showing SRV and URI
use for transport selection.

>     returns ECONNREFUSED if the client could not connect to a server at 

About ICMP unreachables - destination and host unreachables shouldn't
be fed by TCP or SCTP to the application (the reliable transport
treats them as probably transient, e.g. a route flap).  The
ECONNREFUSED example needs a little more precision too, imo.

The text could be more like:

 Diameter implementations SHOULD be
 able to interpret ICMP protocol and port unreachable messages as
 explicit indications that the server is not reachable, in addition
 to interpreting ECONNREFUSED (a reset from the transport)
 and timed-out connection attempts.

Allison

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From: Pat Calhoun <[email-masked]>
Date: Wed, 6 Jun 2001 06:35:34 -0700

>  and timed-out connection attempts.

Great! Thanks for the text.

PatC

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From: Pat Calhoun <[email-masked]>
Date: Wed, 6 Jun 2001 09:38:00 -0700

Just to close this issue, below is the text that I am proposing we
use in -06:

   When connecting to a peer, and either zero or more transports are
   specified, SCTP SHOULD be tried first, followed by TCP. See section
   2.6 for more information on peer discovery.

   Diameter implementations SHOULD be able to interpret ICMP protocol
   and port unreachable messages as explicit indications that the server
   is not reachable, in addition to interpreting ECONNREFUSED (a reset
   from the transport) and timed-out connection attempts.

PatC