[Serusers] Re: GettingStarted Issue04

[Jan Janak]

On 15-07-2005 07:25, Dave wrote:
> Hi,
> I am trying to understand the section 5.1.1
> (mediaproxy ser.cfg analysis) and I am having trouble
> understanding RE-INVITES and loose-routing:
> 
> Consider following scenario:
> 
> UA1 - SER -- P2 - UA2
> 
> 1) When SER gets a REINVITE from UA1, what happens?
> How does SER know it is a REINVITE? Does it work as
> follows: When SER gets a REINVITE, it checks it's
> memory to see if an existing TransactionID exists and
> if yes, then it know that this is a REINVITE? 

  re-INVITE messages have To tag. Normal INVITEs do not have To tag.

> Even if it knows it is a REINVITE, what role does
> loose_route() play? 

  re-INVITE messages are sent within an existing dialog and thus they
  hit the proxy only if the proxy inserted Record-Route header field.

> 2) WHY does the line 85 on page 40 say 
> "n order to ensure that we are dealing only with an
> actual re-INVITE, we must make sure
> the has_totag() function returns TRUE and
> loose_route() is also TRUE."
> Why would the REINVITE have a to_tag()?
 
  See above or RFC3261.

> Why must the loose_route return TRUE for RE-INVITES?
> Won't REINVITES be also record_routed() before
> reaching the loose_route() directive? 
> 
> ANy explanations will be appreciated.

  Jan.