Subject: Re: Re: [Sigtran] The requiremnts and proposals for M2PA/M3UA/SCTPExtension from China Mobile

From: "chenxu" <[email-masked]>
Date: Thu, 26 Jul 2007 14:04:03 +0800

Dear,Brian F. G. Bidulock

	Thank you for your comments!

    For M3UA and SCTP，I'll check if ETSI docs can slove our problems.

    For M2PA, I think national standardization is not enough.
    As I refered in Slides,compared with M3UA and SCTP, Some  procedures in M2PA are  described a little bit simply ,they're referred  to MTP2 directly ,  which  makes IPSTP  providers realizing the  
 procedures in different ways.For  there’s difference between MTP2  
 and M2PA in some aspects. By the protocol test，we find that some IPSTP providers use the same idea as MTP2,and others take the relation between M2PA and SCTP into account.
    Most of the IP Signaling networks exsited are smaller than China Mobile's, only one IPSTP vender is enough .Maybe that's reason why SIGTRAN Working Group hasn't received the Revision Requirement for M2PA.

Best Regards

Chen Xu
China Mobile
[email-masked]
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Sigtran mailing list
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https://www1.ietf.org/mailman/listinfo/sigtran

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 26 Jul 2007 01:42:37 -0600

chenxu,

Please see comments below...

chenxu wrote:                              (Thu, 26 Jul 2007 14:04:03)
>     For M3UA and SCTP£¬I'll check if ETSI docs can slove our problems.

If they can't you likely are expecting M3UA to do something that it was not
intended to do.  M3UA was not intended to replace an SS7 network with an IP
network.  It was intended to provide transparent interworking between an
existing traditional SS7 network and Application Servers in the IP domain.
Primarily for backhaul of SS7 signalling protocols from a Signalling Gateway,
possibley collocated with a Media Gateway, to a Media Gateway Controller.  See
the framework document RFC 2719.

For M3UA IPSP communicating directly with each other, no intervening IPSTP is
necessary.  In the SS7 network, an STP is a relay point.  No relay point for
SS7 is necessary in the IP network: the IP network itself provides for the
routing of packets between source and destination.  Therefore, for M3UA IPSP,
only point to point operation is provided (SS7 relay being unnecessary).
Anything else is trying to recreate the SS7 network within the IP domain,
which was neither part of the framework nor within the scope of the working
group.

>     For M2PA, I think national standardization is not enough.  As I refered
>  in Slides,compared with M3UA and SCTP, Some procedures in M2PA are
>  described a little bit simply ,they're referred to MTP2 directly, which
>  makes IPSTP providers realizing the procedures in different ways.  For
>  there¡¯s difference between MTP2 and M2PA in some aspects.

M2PA procedures are referred to the MTP2 standards particularly where
otherwise it would require that portions of the SS7 MTP Level 2 documents
(e.g. Q.703, ANSI T1.111.3, TTC JQ.703, etc.) would need to be copied directly
into the RFC, an in many cases, different text from each standard, as in: if
ITU-T do this (which is identical to Q.703), but if ANSI do this (which is
identical to T1.111.3).  Then if any of these standards documents are ever
updated, the text would also need to be updated in the M2PA RFC.

Rather than do that, the M2PA RFC only highlights where M2PA is different from
the "applicable" MTP2 specification.  It is up to your national standards
bodies to identify the "applicable" MTP2 specification for M2PA.  Having done
so, I do no see how implementation could possibly realized the procedures in
different ways.

>  By the protocol test£¬we find that some IPSTP providers use the same idea
>  as MTP2,and others take the relation between M2PA and SCTP into account.

IETF RFCs do not place requirements on implementations to do things in a
specific way unless doing so has a negative impact on the Internet, or causes
significant interoperability issues (and here "interoperability" means
functioning at all, not meeting performance or grade of service objectives).
Other things are "operational considerations" that are certainly important to
those operating the service, but not to the network.  It is up to the service
operator to place their own requirements for their own equipment to meet
objectives such as performance and grade of service.  For example, the value
of T7 does not affect the Internet, nor does it affect interoperability.  It
has a large impact on service performance and grade of service.  Therefore it
is up to the service operator to choose its value.

>     Most of the IP Signaling networks exsited are smaller than China
>  Mobile's, only one IPSTP vender is enough.  Maybe that's reason why SIGTRAN
>  Working Group hasn't received the Revision Requirement for M2PA.

All of the telcommunications carriers that I used to work for required STPs
from multiple vendors.  In fact, after the 9-hour AT&T SS7 network outage, it
was required that STPs in an STP pair be from different vendors.  I doubt that
STPs from one vendor (IP or not) is the norm today.  So you are not alone
here.

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

---

From: Gomes, Rui Filipe Efigénio, VF-PT<[email-masked]>
Date: Thu, 26 Jul 2007 11:38:00 +0100

Brian,

Just to give some insight on today's international signalling carriers picture.

>from multiple vendors.  In fact, after the 9-hour AT&T SS7 network outage, >it
>was required that STPs in an STP pair be from different vendors.  I doubt >that

As an example, Vodafone Portugal is connected to several _major_ international signalling carriers (Belgium, Canada, England, Hong Kong, Netherlands, and Portugal) and all use only one vendor facing Vodafone (for TDM and one for SIGTRAN, being the same or not). Other major international signalling carriers that I came to know, use the same principle (not American ones). The same for mobile operators (I know): when more than one vendor are in place, only one is used for the same function (e.g. vendor X for IPSTP, vendor Y for SGW, vendor Z for Signalling based billing, etc).

The reason seems to be that you want to configure your IPSTP/SGW nodes the same way using the same (optional) features (and same team, and same training and same support, etc). 

I understand the AT&T 9 hour outage (or the Swisscom's 11 hour total outage, or other examples that I know and impacted me). But to manage it, carriers (I know) keep only one vendor but use different software versions on different boxes (hoping that new version's bugs only affect half of the network).

Best regards,
Rui Gomes
Vodafone Portugal

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Vodafone (Portugal)

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From: "Brian F. G. Bidulock" <[email-masked]>
Date: Thu, 26 Jul 2007 06:29:46 -0600

Rui,

Is the same true for Vodafone worldwide?  That is, do all Vodafone SS7
interconnects on all points of the globe use the same vendor for TDM?
For SIGTRAN too?  Or, just the one location?

--brian

Gomes, Rui Filipe Efigénio, VF-PT wrote:        (Thu, 26 Jul 2007 11:38:00)
> As an example, Vodafone Portugal is connected to several _major_
> international signalling carriers (Belgium, Canada, England, Hong Kong,
> Netherlands, and Portugal) and all use only one vendor facing Vodafone (for
> TDM and one for SIGTRAN, being the same or not). Other major international
> signalling carriers that I came to know, use the same principle (not
> American ones). The same for mobile operators (I know): when more than one
> vendor are in place, only one is used for the same function (e.g. vendor X
> for IPSTP, vendor Y for SGW, vendor Z for Signalling based billing, etc).
> 
> The reason seems to be that you want to configure your IPSTP/SGW nodes the
> same way using the same (optional) features (and same team, and same
> training and same support, etc). 
> 
> I understand the AT&T 9 hour outage (or the Swisscom's 11 hour total outage,
> or other examples that I know and impacted me). But to manage it, carriers
> (I know) keep only one vendor but use different software versions on
> different boxes (hoping that new version's bugs only affect half of the
> network).
> 
> 
> Best regards,
> Rui Gomes
> Vodafone Portugal
> 
> 
-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

---

From: Gomes, Rui Filipe Efigénio, VF-PT<[email-masked]>
Date: Thu, 26 Jul 2007 16:36:14 +0100

Brian,

>Is the same true for Vodafone worldwide?  
For the opcos I know their international signalling providers, yes (some of the biggest ones in terms of subscribers in Europe).

>That is, do all Vodafone SS7 interconnects on all points of the globe use 
>the same vendor for TDM?
No, even after the big mergers (Nokia+Siemens, Alcatel+Lucent+Nortel, Ericsson+Marconi). 

>For SIGTRAN too?  Or, just the one location?
Same as previous answer.

Best regards,
Rui Gomes
Vodafone Portugal

-----Original Message-----
From: Brian F. G. Bidulock [mailto:[email-masked]] 
Sent: quinta-feira, 26 de Julho de 2007 13:30
To: Gomes, Rui Filipe Efigénio, VF-PT
Cc: chenxu; zhaoyuyi; zhanghao; sigtran
Subject: Re: [Sigtran] The requiremnts and proposals forM2PA/M3UA/SCTPExtension from China Mobile

Rui,

--brian

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/

Vodafone (Portugal)