Subject: RE: [Sigtran] Recommendation for SUA modifications

From: "Haresign Lincoln" <[email-masked]>
Date: Fri, 14 Oct 2005 08:19:02 -0400

Valerie,

I think this is a good solution.  Using the RC also addresses the
scenario of the ASP supporting multiple point codes (not something that
we do, but the RFC supports it).  Since the current SCON message doesn't
indicate that multiple point codes can be specified in the SCON, the RC
parameter would handle this scenario also. 

Regards,
Lincoln

-----Original Message-----
From: Valerie Gastaud [mailto:[email-masked]] 
Sent: Friday, October 14, 2005 4:30 AM
To: Haresign Lincoln; [email-masked]; [email-masked]
Cc: [email-masked]
Subject: RE: [Sigtran] Recommendation for SUA modifications

Lincoln, Brian et all,

Lincoln has explained the problem he tries to solve that requires a
modification to the SCON and I think it's a valid case: SG and ASPs
share the same Point Code and the ASPs are not provisioned with the PC
value.
Let's forget about the usefulness of such architecture. Since I don't
think there are any other problem than SCON to solve in this case, why
not trying to solve it.
I propose the following text:
3.4.4.  Signalling Congestion (SCON)
|             When the SCON is from the ASP to the SG, the affected
point
|             code is an optional parameter.  If not included, the SG
|             must assume the affected PC is its own (primary) Point
Code.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On
Behalf Of Haresign Lincoln
Sent: mercredi 12 octobre 2005 17:02
To: [email-masked]; [email-masked]
Cc: [email-masked]
Subject: [Sigtran] Recommendation for SUA modifications

Lode, John, and the SIGTRAN WG,

With regards to the current SUA RFC, it is my humble opinion that there
is some missing functionality that needs to be defined.  I would like to
propose an addition to the current SUA Implementors Guide that you are
maintaining.

The current SUA RFC indicates that the ASP->SG SCON message is a valid
procedure.  However, I believe that in the case of sending an SCON
message from an ASP to an SG, it is not always necessary to include the
affected DPC in the SCON message.

When the ASP and the SG share the same point code, some architectures
(such as those that use global titles extensively) do not require the
ASP (or the SUA layer in the ASP) to be aware of the point code that is
being used when the SG converts the CL message to an MSU and builds the
L3 MTP routing label.  Therefore, requiring the affected PC in the SCON
message from the ASP to the SG puts and unnecessary burden on the ASP.

There are several ways to solve this problem.  I'm proposing two
possible solutions below.  Personally, I believe the first proposal is a
little cleaner.  I would welcome any and all feedback and/or alternate
solutions.  In the end, I'm no so much concerned with how the problem is
solved.  I would just like a solution that doesn't require the ASP to
have knowledge of the point code being used by the SG if the ASP and SG
share the same point code.

Proposal #1: Use RC

3.4.4.  Signalling Congestion (SCON)

   The SCON message can be sent from the SG or relay node to all
   concerned ASPs to indicate that the congestion level in the SS7
   network to a specified destination has changed.

|  The SCON message can be sent from an ASP to an SG to indicate local  
| congestion.  The receiving SG MAY trigger the congestion procedures
of
|  the relevant SCCP standard.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0006          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                       Routing Context                         /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0012          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                        Affected Point Code                    /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x8003          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              SSN                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0118          |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Congestion Level                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0112          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              SMI                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0004          |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                          Info String                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Routing Context               Optional
|    Affected Point Code           Conditional *1
     SSN                           Optional *1
     Congestion Level              Mandatory
     SMI                           Optional
     Info String                   Optional

|  Note 1:    For an SCON from the SG to an ASP, when the SSN is
included,
              the SCON message corresponds to the SCCP N-STATE
primitive.
              When the SSN is not included, the SCON message corresponds

              to the SCCP N-PCSTATE primitive reporting signalling point

              or network congestion status.

|             When the SCON is from the ASP to the SG, the affected
point
|             code is an optional parameter.  The SG, if necessary, can
|             determine the affected PC from the Routing Context.

Proposal #2: Use Source Address

3.4.4.  Signalling Congestion (SCON)

   The SCON message can be sent from the SG or relay node to all
   concerned ASPs to indicate that the congestion level in the SS7
   network to a specified destination has changed.

|  The SCON message can be sent from an ASP to an SG to indicate local 
| congestion.  The receiving SG MAY trigger the congestion procedures of

| the relevant SCCP standard.

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0006          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                       Routing Context                         /
   \                                                               \
|  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  |         Tag = 0x0102          |            Length             |
|  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  /                        Source Address                         /
|  \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0012          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                        Affected Point Code                    /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x8003          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              SSN                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0118          |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                       Congestion Level                        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0112          |            Length             |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                              SMI                              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |         Tag = 0x0004          |             Length            |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   /                          Info String                          /
   \                                                               \
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Parameters
     Routing Context               Optional
|    Source Address                Optional *1
|    Affected Point Code           Conditional *1
|    SSN                           Conditional *1
     Congestion Level              Mandatory
     SMI                           Optional
     Info String                   Optional

|  Note 1:    For an SCON from the SG to an ASP, when the SSN is
included,
              the SCON message corresponds to the SCCP N-STATE
primitive.
              When the SSN is not included, the SCON message corresponds

              to the SCCP N-PCSTATE primitive reporting signalling point

              or network congestion status.

|             When the SCON is from the ASP to the SG, the ASP can use
|             the source address parameter instead of the Affected Point
|             Code parameter.  This is used mainly in the case when the
|             Routing Keys associated with the ASP may not include a
point
|             code and/or an SSN.  The SG should be able to derive the
affected
|             PC from the registration information and take any actions
|             that might be appropriate to for subsystem congestion in
|             the network.
|
|             If the ASP is sending Source Address, it is not necessary
to
|             send SSN and/or Affected Point Code as this information is

|             either contained in the source address, or can be derived
at
|             the SG.

Regards,
Lincoln Haresign
Comverse, Inc.

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---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Fri, 14 Oct 2005 06:28:22 -0600

Lincoln,

The congestion level only applies to a single point code.  SCCP maintains
a independent congestion level for each point code.

--brian

Haresign Lincoln wrote:                        (Fri, 14 Oct 2005 08:19:02)

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