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Re: [802.21] SAP semantics



Title:
Benjamin: see in-line

Peretz Feder

On 9/6/2006 10:59 PM, Benjamin Koh Tien-Ming wrote:
Hi all!

IMHO, Vivek seems to be saying that unless there are new functions
specifically to be supported by the MIH_NET_SAP, there's no need to
describe a new SAP (Correct me if I'm wrong Vivek).
By this argument we should remove MIH_LINK_SAP.

I basically agree with that viewpoint, having a SAP that basically maps
existing functionality does not seem that critical at this point in
time. Is there any new service unique to the MIH_NET_SAP? It may help
clarify the discussion.
Define means of interface that invoke layer 2 or layer 3 transport mechanism for remote MIHF peers

Regards,
Ben



Peretz Feder wrote:
  
Vivek, pls see in line (red):

*/ /*

*/"The L2 transport functions are provided by media specific SAPs. The
L3 transport functions may be provided by other higher layer services. /*

*/I don’t see the need to introduce another SAP for these transport
functions."
/*

*/
Pls. look at the attached, it is exactly what you are indicating here.
The proposed MIH-NET-SAP is an explanation and illustration of what you
have just described:/*

*/
The L2 transport functions are provided by media specific SAPs.
/*

*/
In the attached pls note the media specific text
/*

*/
/*

*/
The L3 transport functions may be provided by other higher layer

That too is described in the mapping exercise. We are not proposing a
new SAP, just map it properly to L2 and L3.
/*

*/Peretz Feder
/*

*//*

*/
/*



On 9/6/2006 5:00 PM, Gupta, Vivek G wrote:
    
Some comments below.

Best Regards

-Vivek

 

------------------------------------------------------------------------

* *Ajay Rajkumar wrote:

Hong-Yon,

I agree that SAP is defined to provide an abstraction between a
service provider entity and a user entity.
Also, MIH protocol would be used to provide communication between the
two MIHF entities.
The problem arises from the current text in the draft in Section 5.6

"Upper layers may directly send commands to MIHF. Similarly MIHF
entity may also
send commands to another remote (peer) MIHF entity. Primitives
corresponding to all these services
described above are within the scope of MIH_SAP."

*/[Vivek G Gupta] /*

*/This text can be updated. Below is a suggestion for the second part
of this paragraph in section 5.6 (pg 29 of draft D01.09)/*

*/ /*

*/“The MIH_SAP and associated primitives provide the interface from
MIHF to the upper layers of the mobility-management stack. Upper
layers need to register with MIHF as users to receive MIHF generated
events and also for link layer events that originate at layers below
the MIHF but may be passed on to upper layers through MIHF. Upper
layers may directly send commands to MIHF. Similarly MIHF entity may
also send transport these commands and events to another remote (peer)
MIHF entity./* */Primitives corresponding to all these services
described above are within the scope of MIH_SAP/**. **/The L2
transport functions are provided by media specific SAPs. The L3
transport functions may be provided by other higher layer services.”/*

*/ /*

*/I don’t see the need to introduce another SAP for these transport
functions./*

This implies that MIH_SAP is being used both by the MIH User as well
as MIHF to communicate with the remote entity, which is my view is
incorrect.

*/[Vivek G Gupta] /*

*/MIHF does not use MIH_SAP. That notion is indeed incorrect./*

*/The first sentence in paragraph above (copied below) illustrates
that clearly as well./*

*/“The MIH_SAP and associated primitives provide the interface from
MIHF to the upper layers of the mobility-management stack”/*


Regards,
-ajay

*/ /*


Hong-Yon Lach wrote:

Salut all,

A SAP is defined to provide an abstraction of service between a
service provider entity and its user entities in the local system. A
protocol provides a specification of interactions and operations
between “peer” entities in different (sometimes virtual) systems with
well-defined PDUs exchanges over a communications transport.

If a local MIH-user needs a remote services by a remote MIHF, it makes
its request to the local MIHF through the MIH SAP. The local MIHF
determines that it needs the support of a remote MIHF, it thus
performs the necessary operations with the remote MIHF using the MIH
protocol. Upon the end of the MIH protocol operation, the local MIHF
provides a response to the MIH-user via the MIH SAP.

An entity can initiate the execution of its function and/or protocol
by many different triggers: timeout of a timer, request by its users,
detection of certain system conditions, reception of a PDU from its
peer, etc. The entity can initiate its function and/or protocol
without going through its SAP. A SAP is not the only means to have its
serving entity to initiate a function and/or protocol.

I hopes this addresses your concerns.

Cheers,
Hong-Yon