Subject: [Sip] Ready for WGLC on Outbound?

From: Dean Willis <[email-masked]>
Date: Tue, 27 Jun 2006 18:02:47 -0500

Rohan said:

> I'll be on the hook for any outbound-related issues, but AFAIK there
> are no open issues.  The draft has incorporated all the comments we
> received.

So if there are no open issues, are we ready for working group last  
call?

--
Dean

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---

From: Fredrik Thulin <[email-masked]>
Date: Wed, 28 Jun 2006 13:15:22 +0200

On Wednesday 28 June 2006 01:02, Dean Willis wrote:
> Rohan said:
> > I'll be on the hook for any outbound-related issues, but AFAIK
> > there are no open issues.  The draft has incorporated all the
> > comments we received.
>

Hi

I don't consider the question I raised in

  http://www1.ietf.org/mail-archive/web/sip/current/msg13861.html

to have been answered.

I talked briefly with Rohan about this at the last SIPit, but the brief 
explanation he provided me with then didn't convince me =), and I think 
the issue needs to be talked about on the list.

Also, is there consensus to use the 410 response code even though 
RFC3261 says that it is to be considered a permanent condition?

Adam Roach brought this up in

  http://www1.ietf.org/mail-archive/web/sip/current/msg13530.html

/Fredrik

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From: Juha Heinanen <[email-masked]>
Date: Wed, 28 Jun 2006 11:30:31 +0300

> So if there are no open issues, are we ready for working group last  

i sent text to remove the primary/backup stuff and have not seen that
incorporated in any draft.  also, the requirement that UA must be
able to setup at least two flows is not included.

-- juha

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From: Rohan Mahy <[email-masked]>
Date: Wed, 28 Jun 2006 08:35:23 -0700

Hi Juha,

Primary/Secondary terminology was completely removed from the Section 
4.2 of the -04 draft:
> UAs obtain at configuration time one or more SIP URIs representing the 
> default outbound-proxy-set. This specification assumes the set is 
> determined via any of a number of configuration mechanisms and future 
> specifications may define additional mechanisms such as using DNS to 
> discover this set. How the UA is configured is outside the scope of 
> this specification. However, a UA MUST support sets with at least two 
> outbound proxy URIs and SHOULD support sets with up to four URIs. For 
> each outbound proxy URI in the set, the UA MUST send a REGISTER in the 
> normal way using this URI as the default outbound proxy. Forming the 
> route set for the request is outside the scope of this document, but 
> typically results in sending the REGISTER such that the topmost Route 
> header field contains a loose route to the outbound proxy URI. Other 
> issues related to outbound route construction are discussed in 
> [I-D.rosenberg-sip-route-construct].

The only remaining instances of primary/secondary terminology are 
non-normative explanations in one definition, in one scenario described 
in the Overview, and in the example in Section 8.

from Section 2.1 Definitions
> outbound-proxy-set
>     A set of SIP URIs (Uniform Resource Identifiers) that represents 
> each of the outbound proxies (often Edge Proxies) with which the UA 
> will attempt to maintain a direct flow. The first URI in the set is 
> often referred to as the primary outbound proxy and the second as the 
> secondary outbound proxy. There is no difference between any of the 
> URIs in this set, nor does the primary/secondary terminology imply 
> that one is preferred over the other.

from Section 3.3 (part of the Overview):
> In the example system below, the logical outbound proxy/registrar for 
> the domain is running on two hosts that share the appropriate state 
> and can both provide registrar and outbound proxy functionality for 
> the domain. The UA will form connections to two of the physical hosts 
> that can perform the outbound proxy/registrar function for the domain. 
> Reliability is achieved by having the UA form two TCP connections to 
> the domain.
>
> Scalability is achieved by using DNS SRV to load balance the primary 
> connection across a set of machines that can service the primary 
> connection and also using DNS SRV to load balance across a separate 
> set of machines that can service the secondary connection. The 
> deployment here requires that DNS is configured with one entry that 
> resolves to all the primary hosts and another entry that resolves to 
> all the secondary hosts. While this introduces additional DNS 
> configuration, the approach works and requires no addition SIP 
> extensions.
>
>     Note: Approaches which select multiple connections from a single 
> DNS SRV set were also considered, but cannot prevent two connections 
> from accidentally resolving to the same host. The approach in this 
> document does not prevent future extensions, such as the SIP UA 
> configuration framework [I-D.ietf-sipping-config-framework], from 
> adding other ways for a User Agent to discover its outbound-proxy-set.

thanks,
-rohan

---

From: <[email-masked]>
Date: Thu, 29 Jun 2006 08:44:08 +0300

Hi Juha,
 
>also, the requirement that UA must be

In my understanding it is there, however perhaps not so
explicit as you would like it to be mentioned. This is
what the latest draft says:

   UAs obtain at configuration time one or more SIP URIs representing
   the default outbound-proxy-set ... However, a UA MUST support sets
with at
   least two outbound proxy URIs and SHOULD support sets with up to four
   URIs.  For each outbound proxy URI in the set, the UA MUST send a
   REGISTER in the normal way using this URI as the default outbound
   proxy.

In other words UA MUST support a set of 2-4 proxies and set up flows
to as many proxies as ultimately configured or discovered i.e.
1-4. This means there can not be a compliant UA which only supports
one single flow ever.

Regards,

Erkki

>-----Original Message-----
>From: ext Juha Heinanen [mailto:[email-masked]] 
>Sent: 28.June.2006 11:31
>To: Dean Willis
>Cc: IETF SIP List; Rohan Mahy; Cullen Jennings
>Subject: [Sip] Ready for WGLC on Outbound?
>
>Dean Willis writes:
> >

---

From: <[email-masked]>
Date: Thu, 29 Jun 2006 09:20:59 +0300

Hi, 

As Outbound (-04) has now been changed to specify that all the
proxies and flows between those proxies and UAs are handled 
in the equal way, there is a mismatch with it and my latest
draft-koivusalo-sip-outbound-discovery-02.

In this comment:
http://www1.ietf.org/mail-archive/web/sip/current/msg14172.html
I was instructed for outbound-discovery keep two options open:

1. all proxies using the flows actively and balancing the load
   between them

2. have a separate set of idle backup proxies which would be 
   used for routing other SIP requests than REGISTER only in 
   the case when the primary flows will fail

draft-koivusalo-sip-outbound-discovery-02 defines a mechanism
which allows DNS SRV RRs to be configured to ask the UA to use 
the proxies in either of the two ways. However Outbound -04
seems to make this second scheme impossible. Even if the UA
would prefer the primary proxies for sending requests, the
network would still route requests towards the UA over 
whichever flow any proxy has open for that UA. This seems
to prohibit building configurations where N proxies would
be protected with 1 redundant proxy. To me such a scheme
would look potentially useful, but would it make outbound
itself too complicated and not worth the effort ?

In my understanding one of the drafts needs an update for
alignment. Easiest solution would be to drop this second
option from draft-koivusalo-sip-outbound-discovery, but is
the WG happy with such a resolution ?

Regards,

Erkki

>From: ext Rohan Mahy [mailto:[email-masked]] 
>Sent: 28.June.2006 18:35
>To: Juha Heinanen
>Cc: IETF SIP List; Rohan Mahy; Cullen Jennings; Dean Willis
>Subject: Re: [Sip] Ready for WGLC on Outbound?
>
>Hi Juha,
>

---

From: Cullen Jennings <[email-masked]>
Date: Thu, 29 Jun 2006 16:12:26 -0700

Sorry - I messed up and missed that one.

---

From: Juha Heinanen <[email-masked]>
Date: Fri, 30 Jun 2006 17:37:00 +0300

> Primary/Secondary terminology was completely removed from the Section 

yes, i received WGLC message before -04 message.

-- juha