Subject: AW: [Sigtran] M2PA LPO during alignment/proving (was: M2PA versio n 7 changes)

From: Gaiser Franz <[email-masked]>
Date: Fri, 31 Jan 2003 10:45:39 +0100

Hi All,

two additions to the Link State Transition Diagram below: 

1.) Figure 7. M2PA Link State Transition Diagram:
Missing the handling of receiving LS PO in state ALIGNED READY: Situation: After Proving the local side is in state ALIGNED READY and sends LSR; the peer side is in state ALIGNED NOT READY experiencing Processor Outage and starts sending LS PO. To which state the local M2PA is moving ? Transition to PROCESSOR OUTAGE ? If so, the state PROCESSOR OUTAGE handles both local and remote processor outage and then there must be an arrow from PO to IN SERVICE in case of receiving LS PO Recovered (and there is no local PO situation).

2.) Figure 7. M2PA Link State Transition Diagram:
Missing the handling of receiving User data in state ALIGNED NOT READY. Transition to PROCESSOR OUTAGE ? What is to do with this message then (to be discarded) ?

regards, franz 

-----Ursprüngliche Nachricht-----
Von: Brian F. G. Bidulock [mailto:[email-masked]]
Gesendet: Donnerstag, 30. Januar 2003 01:07
An: Tom George
Cc: [email-masked]
Betreff: Re: [Sigtran] M2PA LPO during alignment/proving (was: M2PA
version 7 changes)

Tom,

The problem is the LSC doesn't really have a proving state (only IAC
has proving state).  LSC always moves from INITIAL ALIGNMENT to either
ALIGNED READY or ALIGNED NOT READY.  You might change the diagram as
follows:

 From: 

  |                       |                            |                
  |                       | MTP3 Start                 |                
  |                       V                            |                
  |                 +-----------+                      |                
  |                 |  INITIAL  |                      |                
  +<----------------| ALIGNMENT |--------------------->+                
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |                
  |   OR T2 Expiry        |  ^     OR SCTP Comm Lost   |                
  |   OR Receive LS OOS   |  |                         |                
  |                       |  +-------------------------|--------+      
  |                       |              LPO/LPR       |        |      
  |                       |                            |        |
  |                       | Receive LS Align           |        |
  |                       |                            |        |
  |                       V                            |        |
  |                 +-----------+        LPO/LPR       |        |
  |                 |  PROVING  |<---------------------|--------+
  |<----------------|           |--------------------->+        |
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |        |
  |   OR T3 Expiry        |        OR SCTP Comm Lost   |        |
  |   OR Receive LS OOS   |                            |        |      
  |                       | T4 Expiry                  |        |      
  |                       | Send LS Ready              |        |      
  |                       V                            |        V      
  |                 +-----------+        LPO/LPR       |  +-----------+
  |                 |  ALIGNED  |<---------------------|->|  ALIGNED  |
  +<----------------|   READY   |--------------------->+  | NOT READY |
  |      MTP3 Stop  +-----------+     SCTP Comm Error     +-----------+
  |   OR T1 Expiry        |        OR SCTP Comm Lost         |       |
  |   OR Receive LS OOS   |                                  |   T1  | 
  |   OR Receive LS Align | Receive LS Ready      Receive    | Expiry|
  |                       | OR Receive User Data    LS Ready | OR Rcv|
  |                       |                       OR Receive |    LS |
  |                       |                         LS PO    |  Align|
  |                       |                                  |       |

 To:

  |                       |                            |               
  |                       | MTP3 Start                 |               
  |                       V                            |               
  |                 +-----------+        LPO/LPR       |  +-----------+
  |                 |  INITIAL  |<---------------------|->|  INITIAL  |
  +<----------------| ALIGNMENT |--------------------->+  | ALIGNMENT |
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |  +-----------+
  |   OR T2 Expiry        |        OR SCTP Comm Lost   |        |      
  |   OR Receive LS OOS   |                            |        |      
  |                       | Receive                    |   Recv |      
  |                       | LS Align                   |     LS |      
  |                       |                            |  Align |      
  |                       V                            |        V      
  |                 +-----------+        LPO/LPR       |  +-----------+
  |                 |  PROVING  |<---------------------|->|  PROVING  |
  |<----------------|           |--------------------->+<-|           |
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |  +-----------+
  |   OR T3 Expiry        |        OR SCTP Comm Lost   |        |      
  |   OR Receive LS OOS   |                            | T4 Exp |      
  |                       | T4 Expiry                  |   Send |      
  |                       | Send LS Ready              |  LS PO |      
  |                       V                            |        V      
  |                 +-----------+        LPO/LPR       |  +-----------+
  |                 |  ALIGNED  |<---------------------|->|  ALIGNED  |
  +<----------------|   READY   |--------------------->+  | NOT READY |
  |      MTP3 Stop  +-----------+     SCTP Comm Error     +-----------+
  |   OR T1 Expiry        |        OR SCTP Comm Lost         |       | 
  |   OR Receive LS OOS   |                                  |   T1  | 
  |   OR Receive LS Align | Receive LS Ready      Receive    | Expiry| 
  |                       | OR Receive User Data    LS Ready | OR Rcv| 
  |                       |                       OR Receive |    LS | 
  |                       |                         LS PO    |  Align| 
  |                       |                                  |       | 
  |                       |                                  |       | 
  |                       V                                  V       | 
  |                 +-----------+        LPO/LPR       +-----------+ | 
  |                 |    IN     |<-------------------->| PROCESSOR | | 
  |                 |  SERVICE  |                      |   OUTAGE  | | 
  |                 +-----------+                      +-----------+ | 

This would indicates that the LSC moves from INITIAL ALIGNMENT to
ALIGNED READY or ALIGNED NOT READY regardless of PROVING.  That is what the
line from INITIAL alignment to ALIGNED NOT READY was intended to indicate
in shorthand.

I suppose one could draw it as:

  |                       | MTP3 Start                 |               
  |                       |                            |               
  |                       |   +-------+                |               
  |                       |   |       | LPO/LPR        |               
  |                       V   V       |                |               
  |                 +-----------+     |                |               
  |                 |  INITIAL  |<----+                |               
  +<----------------| ALIGNMENT |--------------------->+               
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |               
  |   OR T2 Expiry        |        OR SCTP Comm Lost   |               
  |   OR Receive LS OOS   |                            |               
  |                       | Receive                    |               
  |                       | LS Align                   |               
  |                       |                            |               
  |                       |   +-------+                |               
  |                       |   |       | LPO/LPR        |               
  |                       V   V       |                |               
  |                 +-----------+     |                |               
  |                 |  PROVING  |<----+                |               
  |<----------------|           |--------------------->+               
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |               
  |   OR T3 Expiry        | |      OR SCTP Comm Lost   |               
  |   OR Receive LS OOS   | |                          |               
  |                       | +--------------------------|--------+      
  |                       |                            |   T4   |      
  |                       | T4 Expiry                  | Expiry |      
  |                       | Send LS Ready              | Send   |      
  |                       V                            | LS PO  V      
  |                 +-----------+        LPO/LPR       |  +-----------+
  |                 |  ALIGNED  |<---------------------|->|  ALIGNED  |
  +<----------------|   READY   |--------------------->+  | NOT READY |
  |      MTP3 Stop  +-----------+     SCTP Comm Error     +-----------+
  |   OR T1 Expiry        |        OR SCTP Comm Lost         |       | 
  |   OR Receive LS OOS   |                                  |   T1  | 
  |   OR Receive LS Align | Receive LS Ready      Receive    | Expiry| 
  |                       | OR Receive User Data    LS Ready | OR Rcv| 
  |                       |                       OR Receive |    LS | 
  |                       |                         LS PO    |  Align| 
  |                       |                                  |       | 
  |                       |                                  |       | 
  |                       V                                  V       | 
  |                 +-----------+        LPO/LPR       +-----------+ | 
  |                 |    IN     |<-------------------->| PROCESSOR | | 
  |                 |  SERVICE  |                      |   OUTAGE  | | 
  |                 +-----------+                      +-----------+ | 

The effect is the same.  The diagram is certainly not intended to be 100%
complete, it is an overview.  The text should be consulted.

--brian

Tom George wrote:                                   (Wed, 29 Jan 2003 17:18:23)
> IMHO if there is a local PO while in INITIAL ALIGNMENT, M2PA should
> continue sending/receiving LS Alignment, i.e., remain in INITIAL
> ALIGNMENT. 
> 
> After the LS Alignment is sent and received, M2PA would move to PROVING
> and send/receive LS Proving messages. 
> 
> When T4 expires, it seems to me that M2PA would go ahead and
> send/receive the LS Ready messages. That's the ALIGNED READY state. 
> 
> In short, it looks to me that if there is a local PO, M2PA should
> continue with alignment and proving and should not go into ALIGNED NOT
> READY until it is completed with the ALIGNED READY state.
> 
> Or if M2PA does go to ALIGNED NOT READY earlier than that, it should
> continue doing what it would have done in INITIAL ALIGNMENT, PROVING,
> and ALIGNED READY. Which looks like a confusing way to explain it. 
> 
> tomG.
> 
> Gaiser Franz wrote:
> > 
> > Dear All,
> > 
> > some remarks to the new draft version 07:
> > 
> > 1.)  Figure 7. M2PA Link State Transition Diagram:
> > Why is there an arrow from state INITIAL ALIGNMENT to state 
> > ALIGNED NOT READY  ? If the local side is in processor outage, 
> > the PROVING period should be passed before moving to 
> > ALIGNED NOT READY state.
>   [...]
> 
> -- 
> * Tom George       PB7-24001 (near B-21)      [email-masked]  *
> * 972-519-3168   Intranet:  http://www.ssd.usa.alcatel.com/~tgeorge/  *
> * Alcatel USA, Inc.; 1000 Coit Rd, MS PB7-SWPRO; Plano TX 75075-5813  *
> * I actively disclaim speaking for Alcatel USA, Inc. I do not purport *
> * to advertise or represent its position,  operations, or activities. *
> _______________________________________________
> Sigtran mailing list
> [email-masked]
> https://www1.ietf.org/mailman/listinfo/sigtran

-- 
Brian F. G. Bidulock
[email-masked]
http://www.openss7.org/
_______________________________________________
Sigtran mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/sigtran
_______________________________________________
Sigtran mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/sigtran

---

From: Tom George <[email-masked]>
Date: Wed, 05 Feb 2003 11:28:35 -0600

Franz,

Comments below...

> Missing the handling of receiving LS PO in state ALIGNED READY: Situation: After Proving the local side is in state ALIGNED READY and sends LSR; the peer side is in state ALIGNED NOT READY experien…

If M2PA is in ALIGNED READY and receives LS PO, it should go to ALIGNED
NOT READY. When it gets LS Ready from the other end, then it would go to
PROCESSOR OUTAGE. 

I updated the diagram accordingly. See below.

> Missing the handling of receiving User data in state ALIGNED NOT READY. Transition to PROCESSOR OUTAGE ? What is to do with this message then (to be discarded) ?

We are in the middle of discussing this in another thread. It looks like
User Data should not be sent/received when in ALIGNED NOT READY. If it
can happen, it would be an error case that I would prefer not to show in
the diagram.

> regards, franz

Updated piece of the diagram:

  |                       |   +-----+                  |                
  |                       |   |     | LPO/LPR          |                
  |                       V   V     |                  |                
  |                 +-----------+   |                  |
  |                 |  PROVING  |---+                  |
  |<----------------|           |--------------------->+
  |      MTP3 Stop  +-----------+     SCTP Comm Error  |
  |   OR T3 Expiry        |  |     OR SCTP Comm Lost   |
  |   OR Receive LS OOS   |  |                         |
  |                       |  +-------------------------|--------+
  |                       |     T4 Expiry              |        |      
  |                       |     Send LS PO             |        |      
  |                       |                            |        |      
  |                       | T4 Expiry                  |        |      
  |                       | Send LS Ready              |        |      
  |                       |                            |        |      
  |                       |                            |        |      
  |                       V           SCTP Comm Error  |        V      
  |                 +-----------+  OR SCTP Comm Lost   |  +-----------+
  |                 |  ALIGNED  |--------------------->+  |  ALIGNED  |
  +<----------------|   READY   |<----------------------->| NOT READY |
  |      MTP3 Stop  +-----------+     LPO/LPR             +-----------+
  |   OR T1 Expiry        |        OR Receive LS PO/PR       |       |
  |   OR Receive LS OOS   |                                  |   T1  | 
  |   OR Receive LS Align | Receive LS Ready      Receive    | Expiry|
  |                       | OR Receive User Data    LS Ready | OR Rcv|
  |                       |                                  |    LS |
  |                       |                                  |  Align|
  |                       |                                  |       |
  |                       V                                  V       |
  |                 +-----------+                      +-----------+ |
  |                 |    IN     |<-------------------->| PROCESSOR | |
  |                 |  SERVICE  |     LPO/LPR          |   OUTAGE  | |
  |                 +-----------+  OR Receive LS PO/PR +-----------+ |
  |                       |                                  |       |
  |                       |                                  |       |

* Alcatel;  3400 West Plano Pkwy,  MS PB7-SWPRO;  Plano, Texas 75075  *