Subject: Re: [Sigtran] About the Notify message in SUA

From: "Rabindra Nath Tiwari" <[email-masked]>
Date: Sat, 14 Nov 2009 16:18:27 +0530

Hi Prasanna,

See the comments inline in green below.

Thanks and Regards,

Rabindra Nath Tiwari

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On
Behalf Of Prasanna Kumar
Sent: Friday, November 13, 2009 12:57 PM
To: [email-masked]
Subject: Re: [Sigtran] About the Notify message in SUA

Hi,

Thanks for your response. Have some doubts in case of IPSP mode. For

IPSP mode, the RFC says that it will work in similar way to AS-SG

mode. So that means receptor of ASPUP/ASPAC message has to send the

Notify in this case also right?

Yes, the receptor of ASP-UP/ASP-AC message will send the NOTIFY.

Is it required to exchange 2 Notify message in case of IPSP-SE? If

not, which one has to send the Notify message (weather receiver/sender

of ASPUP/ASPAC)? The RFC says any one can send so, is this

implementation dependent? Following is the RFC section:

Unlike IPSP-DE mode, in IPSP-SE mode it is not required to exchange two
NOTIFY messages, since the traffic is symmetric (RC is same in both the
directions of traffic).

Also, as mentioned in RFC that NOTIFY works in the same manner as in the
SG-AS case. The IPSP end assuming the role of Server (i.e. the end
receiving ASP-UP/ASP-AC) MUST send the NOTIFY message. 

I believe that in the sentence "One of the IPSPs can .........." RFC
indicates that any end can assume a role of Client/Server for the
ASPSM/ASPTM message exchanges. I.e. it may happen that one end assumed a
role of Client and sent ASP-UP message, but the transmission of the
subsequent ASP-AC message can be initiated by the other end, thus making
it a valid scenario. Hence, the transmission of NOTIFY for a particular
ASPTM/ASPSM message exchange will depend upon that which end assumed the
role of Server in that message exchange. The end assuming the role of
Server will send the NOITFY after sending the respective ASPSM/ASPTM ACK
message.

4.3.4.5.1.  IPSP Considerations (NTFY)

"Notify works in the same manner as in the SG-AS case.  One of the

IPSPs can send this message to any remote IPSP that is not in the

ASP-DOWN state."

Regards,

Prasanna.