Re: M3UA notify message
"nitin" <[email protected]>
| Newsgroups | gmane.ietf.sigtran |
|---|---|
| Message-ID | <004001c63887$16c61ae0$2c01a8c0@Nitinnew> |
I am explaining some scenarios :-
1. Consider SG consisting of SGP1 and SGP2.
Suppose an AS contain one ASP and the traffic mode of AS is override.
If we look in terms of SGP then this override mode
is of no use, but if we look in terms of SG and this ASP is making associations with
two SGP then this is of much significance. Actually for SGP , ASP is identified by
the sctp association . For even if there is only one ASP in AS but for SGP's they
don't know this ASP as single ASP.
Please take AS as inactive initially on both SGP's.
ASP SGP1 SGP2 SG
| aspAc | | |
|---------------->| | | ( please note here that i have drawn notify from SG,
|<-----------------| | | just to highlight that state of AS is maintained at SG,
| asp ac ack | | | so logically this notify is sent with respect to SG)
|<--------------------------------------------------|
| notify AS active | |
| | | |
|---aspAc------------------------>| |
| aspac ack | | |
|<----------------------------------| |
| notify Alt. Asp Ac. | |
|<--------------------------------------------------|
| | | |
| | | |
Now sicne when we have configured AS at the SG, we have configured that AS has only one SGP
in override mode. However this override mode doesn't makes sense with one ASP in AS.
But here what is happening that SGP's doesnot know , that it is the same ASP which is doing
active with both SGP's. So when ASP does active with SGP1 then AS becomes active. Now when
ASP does active with SGP2 this is new ASP for SGP2. So what should be done in this case.Should
Alternate ASP active notify be sent in this case to same ASP .
2. Now consider another case.
In this scenario , ASP1 and ASP2 are both part of AS and SGP1 and SGP2 are both part of SG1.
In this case assume that ASP1 and ASP2 are both inactive at their respective SGP's.
Now my question is little bit different in this case as explained below:-
ASP1 ASP2 SGP1 SGP2
| aspAc | | |
|--------------------------------->| |
|<---------------------------------| |
| asp ac ack | | |
|<--------------------------------| |
| notify AS active | |
| | | |
| data | |
|---------------------------------->
| | | |
| | |
| | |
| |
| | | |
| | | |
Should this data message be dropped at SG or should it be allowed to SS7 side , Since AS is active at SG
but ASP2 is not active on SGP2.
3. Now here is the 3rd scenario , this is related to n+k AS.
In this case , configuration is AS consisting of ASP1 and ASP2.
SG consisting of SGP1 and SGP2.
Obviously the traffic mode is loadshare.
Now only ASP1 is doing ASP active on SGP1 and SGP2.
ASP2 has not done any m3ua procedures with neither SGP1 , nor SGP2.
ASP1 ASP2 SGP1 SGP2
| aspAc | | |
|--------------------------------->| |
|<---------------------------------| |
| asp ac ack | | |
| | |
| | |
| | | |
|----------asp Ac.---------------------------------------->|
<-----------ASP act . ack--------------------------------------- |
| | |
|<----------------------------------------------------|
| |
| | | |
| | | |
Now since ASP1 has done active on both SGP1 and SGP2 , it is active on two SGP's.
So with respect to SG two SGP's are active. Should in this case AS be active or not.
thanks
nitin
----- Original Message -----
From: "Brian F. G. Bidulock" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Thursday, February 23, 2006 11:34 AM
Subject: Re: [Sigtran] M3UA notify message
> Prabind,
>
> You are correct, there is a case where the ASP state is shared across
> the SGPs making up an SG: in the Override traffic mode AS it is
> necessary to share which ASP is "Active" and which is "Standby" as only
> one ASP can be Active for the AS.
>
> This is also a case where state transitions directly associated with
> ASPTM/ASPSM message procedures must be considered on an SG-wide basis,
> contrary to Tolga's previous statements on this thread.
>
> It is possible, but perhaps less important to interoperability, that an
> SG could coordinate the ASP state for ASPs in a Loadshare or Broadcast
> AS. That is, when loadsharing, the selection algorithm at an SGP could
> consider the availability of ASPs to other SGPs to more equally
> distribute traffic. For Broadcast mode AS, consideration of ASP state
> across the SGP could provide a more optimal broadcast of traffic (i.e.
> without sending multiple messages to or missing completely an ASP).
>
> For the case of SSNM, it is possible (but not required) for the SG to
> avoid sending duplicate SSNM messagese to any given ASP. By considering
> the ASP state on an SG-wide basis, it is possible to ensure that only
> one SSNM message is sent to an ASP (via only one SGP).
>
> The override and SSNM cases were given consideration in the original
> thread that led to the wording 1.4.1. The others were not so much.
>
> Therefore, I agree that the statement in 1.4.1 should not be ammended.
>
> --brian
>
>
> [email protected] wrote: (Thu, 23 Feb 2006 09:50:04)
> >
> > I am still concerned about this statement from Tolga:
> >
> > " In any case, it is good that there is finally consensus regarding that
> > ASPSM/ASPTM procedures and associated state machines being independent
> > on
> > each SGP."
> >
> > If multiple SGPs are serving a single AS, then shouldn't the ASP states
> > also be shared across the related SGPs?
> > Else if I am wrong then the following statement in section 1.4.1 should
> > be amended to share the AS states only.
> > " Where an SG contains more than one SGP, the MTP3 routeset, SPMC and
> > remote AS/ASP states of each SGP SHOULD be coordinated across all the
> > SGPs."
> >
> > Tolga, further considering the sahring of ASP states then, in the case
> > of the interoperability issue (as you depicted), the rfc says that if an
> > ASP is already inactive the ASP-UP message would still be respnded by an
> > ack.
> >
> > I think the things become simpler if we consider sharing of ASP states
> > of a particular AS across all SGPs serving that AS.
> >
> >
> > Regards,
> >
> > Prabind
> >
>
> --
> Brian F. G. Bidulock
> [email protected]
> http://www.openss7.org/
>
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