Subject: [Sigtran] Link States during Intial Alignment in M2PA

From: "pardeep" <[email-masked]>
Date: Mon, 28 Apr 2003 15:36:31 +0530

All,
   
What's the need to copy all the states (Initial alignment, alignment, proving, aligned ready) from Q.703 to M2PA? I think these states are required only in case of traditional SS7 stack & not in M2PA. 

e.g Not Aligned State is used in MTP2 to tell that MTP2 can no longer delineate the SU based upon receipt of a flag, mean it has lost its timing. Similarly Aligned state in MTP2 is used to tell that MTP2 is now capable of detecting the flags and Proving state in MTP2 is used to check the integrity of Link. 
As in case of M2PA, SCTP is reliable protocol & it establish SCTP association after getting POWER ON from MTP3 so by the time MTP3 will give START REQUEST reliable transport (SCTP) will be ready (Isn't it equal to aligned ready of MTP2?). So I think that In M2PA there is no need to keep all these states. 

So after getting START REQUEST from MTP3, M2PA peers can exchange only STATUS_READY. M2PA can start its own timer (say WAIT_TIMER) while waiting for STATUS_READY from peer. In case of normal proving its value can be (T2_MAX+T3_MAX+T4_NORMAL+T1_MAX). In case of emergency proving its value can be (T2_MAX+T3_MAX+T4_EMERGENCY+T1_MAX). If with in WAIT_TIMER it doesn't receive STATUS_READY or STATUS_LPO from peer then M2PA can report to MTP3 about LINK_OOS & can send LINK_OOS to remote.

Thanks

Pardeep

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Mon, 28 Apr 2003 05:34:29 -0600

pardeep,

On Mon, 28 Apr 2003, pardeep wrote:

> 
>    All,
> 
> 
> 
>    What's  the need to copy all the states (Initial alignment, alignment,
>    proving,  aligned  ready) from Q.703 to M2PA? I think these states are
>    required only in case of traditional SS7 stack & not in M2PA.
> 
> 
> 
>    e.g  Not Aligned State is used in MTP2 to tell that MTP2 can no longer
>    delineate  the  SU  based upon receipt of a flag, mean it has lost its
>    timing.  Similarly  Aligned state in MTP2 is used to tell that MTP2 is
>    now  capable  of detecting the flags and Proving state in MTP2 is used
>    to check the integrity of Link.

The above couldn't be more wrong.  DAEDR checks flag alignment and signals
this to AERM/SUERM which results in link failure (Out of Service state,
not aligned or not aligned states).  Aligned and not aligned states require
the exchange of SIO, not flag delimitation.

--brian

> 
>    As  in  case  of  M2PA,  SCTP is reliable protocol & it establish SCTP
>    association  after getting POWER ON from MTP3 so by the time MTP3 will
>    give  START  REQUEST reliable transport (SCTP) will be ready (Isn't it
>    equal  to aligned ready of MTP2?). So I think that In M2PA there is no
>    need to keep all these states.
> 
>    So after getting START REQUEST from MTP3, M2PA peers can exchange only
>    STATUS_READY.  M2PA  can  start  its  own timer (say WAIT_TIMER) while
>    waiting  for  STATUS_READY  from  peer.  In case of normal proving its
>    value  can  be  (T2_MAX+T3_MAX+T4_NORMAL+T1_MAX). In case of emergency
>    proving  its value can be (T2_MAX+T3_MAX+T4_EMERGENCY+T1_MAX). If with
>    in  WAIT_TIMER it doesn't receive STATUS_READY or STATUS_LPO from peer
>    then  M2PA  can  report  to MTP3 about LINK_OOS & can send LINK_OOS to
>    remote.
> 
>    Thanks
> 
>    Pardeep

-- 
Brian F. G. Bidulock    ¦ The reasonable man adapts himself to the ¦
[email-masked]    ¦ world; the unreasonable one persists in  ¦
http://www.openss7.org/ ¦ trying  to adapt the  world  to himself. ¦
                        ¦ Therefore  all  progress  depends on the ¦
                        ¦ unreasonable man. -- George Bernard Shaw ¦
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---

From: "pardeep" <[email-masked]>
Date: Mon, 28 Apr 2003 19:05:03 +0530

No comments on whether these states are required in M2PA?

----- Original Message -----
From: "Brian F. G. Bidulock" <[email-masked]>
To: "pardeep" <[email-masked]>
Cc: "SIGTRAN e-mail list" <[email-masked]>
Sent: Monday, April 28, 2003 5:04 PM
Subject: Re: [Sigtran] Link States during Intial Alignment in M2PA

pardeep,

--brian

---

From: "pardeep" <[email-masked]>
Date: Tue, 29 Apr 2003 10:42:25 +0530

pardeep,

--brian

but MTP2 starts AERM only in proving period & not in not-aligned or aligned
state.

My question was why to keep not-aligned & aligned states in M2PA? What
purpose these are solving here? Read the below paraggraph..

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 29 Apr 2003 03:26:59 -0600

pardeep,

> purpose these are solving here? Read the below paraggraph..

Read Q.2140.  It also has not-aligned and aligned states.  Setup of the SSCOP
connection is separate from the alignment of the link.  M2PA does not need to
deviate from both Q.703 and Q.2140.

--brian

---

From: "pardeep" <[email-masked]>
Date: Tue, 29 Apr 2003 17:43:10 +0530

pardeep,

> purpose these are solving here? Read the below paraggraph..

Read Q.2140.  It also has not-aligned and aligned states.  Setup of the
SSCOP
connection is separate from the alignment of the link.  M2PA does not need
to
deviate from both Q.703 and Q.2140.

--brian

My understanding is M2PA shouldn't keep these states just because other
protocols are keeping these. We don't know about the issues raised at the
time when those protocols were developing. Now M2PA is a new protocol.
M2PA's objective (along with SCTP) should be to provide the same
functionality as MTP2 provides. To provides these M2PA should think its own
like its doing in case of FISU, FIB, BIB, LI etc. We cann't say that by not
providing these, M2PA is deviating from MTP2 but the fact is M2PA doesn't
need to provide this functionality because SCTP is taking care of it.

Same is the case of state machine. I am again sticking to my point that some
states (like initial alignement, alligned etc) aren't required at all in
M2PA (Pl. refer below paragraphs). M2PA could provide the same functionality
as MTP2 without having these states.

& also thanks for your responses .. hope the same in future also.. & hope
others will also participate in this discussion.

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 29 Apr 2003 06:02:22 -0600

pardeep,

On Tue, 29 Apr 2003, pardeep wrote:

> SSCOP connection is separate from the alignment of the link.  M2PA does not
> need to deviate from both Q.703 and Q.2140.
> 
> --brian
> 

You should take the time to understand how these states are necessary and
useful in Q.703 and Q.2140 before you dismiss them out of hand for M2PA.

> others will also participate in this discussion.

We have already completed one round of LC on M2PA.  Drastic changes such as
this are against the existing concensus and are unlikely to be made before
the draft is advanced.

--brian

---

From: "pardeep" <[email-masked]>
Date: Tue, 29 Apr 2003 19:09:55 +0530

pardeep,

--brian

I agree. But implementation of this will make M2PA design simpler & more
efficient, which is the ultimate goal of all of us. I hope to see this
change soon.

--Pardeep

---

From: "Brian F. G. Bidulock" <[email-masked]>
Date: Tue, 29 Apr 2003 08:07:00 -0600

pardeep,

> efficient, which is the ultimate goal of all of us. I hope to see this

I disagree: it is quite efficient (and compatible with MTP3) to follow the
precedent established by Q.703 and Q.2140.  Alignment and proving increases
MTP performance.  Discarding them would decrease MTP performance.  Take the
time to understand them before jumping to sweeping conclusions.

--brian

---

From: Tom George <[email-masked]>
Date: Tue, 29 Apr 2003 11:51:47 -0500

Pardeep,

The states during alignment correspond to steps in the handshaking
procedure that the peers use to make sure they are both ready for
traffic. Eliminating steps in the procedure increases the risk that one
end will send traffic that the other end is not ready to accept. That
would be efficient but bad. 8-)

Once upon a time I wanted M2PA to be a much simpler protocol than MTP2.
But once the decision was made to support an alignment procedure,
processor outage, and deal with level 2 congestion, M2PA was going to be
similar to MTP2 in complexity. Those procedures are there for a purpose,
so it is necessary to support them. That includes being able to deal
with various inputs in different states. 

tomG.

pardeep wrote:
  [...] 
> efficient, which is the ultimate goal of all of us. I hope to see this
  [...]

-- 
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