Subject: [Dime] Redirect-Host-Usage AVP

From: Preeti Shandilya <[email-masked]>
Date: Wed, 27 Feb 2008 11:11:36 +0530

Hi !

Description of Redirect-Host-Usage AVP in the bis of RFC3588 (bis 9) 
indicates that it can have value ALL_SESSION

So if redirect agent sends Redirect-Host-Usage AVP as ALL_SESSION, this 
indicates that client should send all the session oriented messages to the 
same redirect host usage , which redirect agent has informed in the 
redirect indication, at the start of the session. In my opinion, this 
possible value of Redirect-Host-Usage AVP is 'redundant'. There shall be 
no practical scenario, when subsequent message on the same session may to 
different host.

In my opinion, we should not have ALL_SESSION as a possible value of the 
Redirect-Host-Usage AVP and should assume that all the  session oriented 
message should go to the same host to which first message corresponding to 
that session was sent. The time limit for which this routing is valid 
shall of-course be driven by Redirect-Max-Cache-Time AVP

Let me know if I am missing something here

regards
Preeti

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---

From: Victor Fajardo <[email-masked]>
Date: Wed, 27 Feb 2008 09:09:05 -0500

Hi Preeti,
> shall of-course be driven by Redirect-Max-Cache-Time AVP

I guess the point of ALL_SESSION is: how will you know to redirect 
messages for this session in the first place unless you get an 
ALL_SESSION redirection.

regards,
victor

---

From: Preeti Shandilya <[email-masked]>
Date: Fri, 29 Feb 2008 09:49:31 +0530

Hi Victor !

Thanks for your response.

Redirect agent should provide the redirect host AVPs , solely based upon 
the routing tables available at the redirect agent. It should not concern 
about any session ! So all the possible values for Redirect-Host usage 
AVPs mentioned in the RFC, except ALL_SESSION, somehow indicates the 
routing table at the redirect agent. 

For finding the route for the first message, from the redirect agent, is 
responsibility of the client. Why should redirect agent be concerned about 
whether it is first message or the subsequent message for the session

regards
Preeti

Victor Fajardo <[email-masked]> 
Sent by: [email-masked]
02/27/2008 07:39 PM

To
Preeti Shandilya/HSS@HSS
cc
[email-masked]
Subject
Re: [Dime] Redirect-Host-Usage AVP

Hi Preeti,

regards,
victor

---

From: "G Nadaf Liyaqatali-a21917" <[email-masked]>
Date: Fri, 29 Feb 2008 13:21:31 +0800

Hi Preeti

Your argument is that after an initial message of a session is sent to a host, all the subsequent messages should be sent to the same host. This is not necessarily true. 

1. The redirect agent can be a load balancer. In which case, it can chooses an appropriate host based on how the servers are loaded. And yes, in this case all the servers have to be in sync. There are implementations that support this.

2. In IMS, during registration, the S-CSCF before sending MAR and SAR belonging to the same user same session can contact the SLF(redirect agent) in a multiple HSS network deployment. Even in this case, SLF may return different host names each time. Again, HSSes have to be in sync. Further, In multiple SLF deployment, this is more likely to happen.

Regards
Liyaqatali G Nadaf

-----Original Message-----
From: [email-masked] on behalf of Preeti Shandilya
Sent: Fri 2/29/2008 9:49 AM
To: Victor Fajardo
Cc: [email-masked]; [email-masked]
Subject: Re: [Dime] Redirect-Host-Usage AVP
 
Hi Victor !

regards
Preeti

To
Preeti Shandilya/HSS@HSS
cc
[email-masked]
Subject

Hi Preeti,

regards,
victor