Re: Sigtran extension for network management and association changeover.

Dear Brian,

Thanks for your attention, please see inline.

Regards
Xiangsong

----- Original Message ----- 
From: "Brian F. G. Bidulock" <[email protected]>
To: "Xiangsong Cui" <[email protected]>
Cc: <[email protected]>
Sent: Thursday, March 04, 2010 4:08 PM
Subject: Re: [Sigtran] Sigtran extension for network management and association changeover.


> Xiangsong,
> 
> Xiangsong Cui wrote:                      (Thu, 04 Mar 2010 11:48:15)
>> 
>> http://tools.ietf.org/id/draft-cui-tsvwg-snm-ps-00.txt
>> Abstract: 
>>   Sigtran is widely applied in the telecommunication network but there 
>>   are still some issues. This document briefly describes some concerned 
>>   scenarios and presents the association changeover and Sigtran routing 
>>   management problems. The goal of this document is to analyse the 
>>   existing shortage of Sigtran and discuss the desirable improvements. 
> 
> I believe these issues were already addressed in the 3GPP Liaison
> statement of April 2008.  Note that 3GPP (which you cite in the
> document) does not permit M3UA RK's at granularity of less than
> a signalling point code.

If you mean https://datatracker.ietf.org/documents/LIAISON/file552.txt,
I think the issues are not all resolved.
Changeover issue (I guess you agree this is a problem after I see your draft) 
is not mentioned in this liaison and the routing management issue is not 
resolved as you said.
The liaison says "However, this approach has some drawbacks, 
expecially if multiple SGs are used." and "There was some discussion within
the Working Group about potential extensions to overcome these drawbacks,
but no consensus was reached." Do I miss any important information?

In addition, in some practical scenario, even one SG, we also met some troubles.
For example, in the basic case of GSM + softswitch, some BSC devices
can not support multiple adjacent SP, unfortunately the BSCs can't be updated 
too. So the MGW has to share the SP code with the MSC Server, but we need
install SCCP in both MGW (for SGW/STP purpose) and MSC Server (for 
MAP purpose). The duplicated combinations of "SP Code + SCCP User Part" 
bring problems for the network. If we use M2UA for GSM access, the complexity
increases explicitly. Is this also a drawback?

> 
>> 
>> http://tools.ietf.org/id/draft-cui-tsvwg-assoc-changeover-00.txt
>> Abstract:
>>   Sigtran specifies association-level reliable transport for signaling 
>>   using SCTP, but in some scenarios a single association failure's 
>>   reliability mechanism is not sufficient to achieve telco reliability. 
>>   This document specifies procedures for an SCTP association changeover 
>>   solution which will enable applications to meet a higher degree of 
>>   availability. Two generic changeover solutions are presented in this 
>>   document. One is implemented inside the SCTP protocol stack and the 
>>   other requires SCTP and ULP to work in collaboration. 
> 
> http://tools.ietf.org/html/draft-bidulock-sigtran-corid-05 provides
> several mechanisms that are completely local and accomplish this
> without protocol changes: neither in SCTP nor the UA.  UAs, such as
> M3UA, provide CorrelationId/Ack, BEAT/Ack, and ASPTM on data streams
> that already accommodate these procedures.
> 
I am glad to see this draft, but I need some time to read through it.
We can discuss this item later.

Thanks, Xiangsong

> --brian
> 
> -- 
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/