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RE: [802.21] SAP semantics

Title:
Hi Adrian and all,
 
What you described is generally true. However, with regard to the original question, I don't think it is necessary to have two separate SAPs.
 
The question regarding the remote MIH communication is different from a local use case. In a remote scenario, conceptually, the local MIHF becomes a user of the remote MIHF. The command is sent via the MIH Protocol (either via L2 or L3), and should be processed by the remote MIHF. In this case, there should be no problem for the remote MIHF to make use of the MIH_SAP for the commands come in via the MIH Protocol, since functions supported over the MIH protocol should not be different from that of the local MIHF. Therefore, it is rather an optimized design.
 
cheers
 
Cheng Hong
 

From: stds-802-21@ieee.org [mailto:stds-802-21@ieee.org] On Behalf Of Stephens, Adrian P
Sent: Monday, September 04, 2006 3:09 PM
To: Phillip Barber; Peretz Feder
Cc: Andrea Francini; STDS-802-21@listserv.ieee.org
Subject: RE: [802.21] SAP semantics

Hello All,
 
While Phillip's answer is correct,  I'd say it's not optimal.
 
The SAP should group together all the primitives that are required
for one instance of a particular entity to provide services to an instance
of another entity.
 
If each entity is providing services to the other,  I'd respectfully
suggest that two SAPs should be provided.   This should make the
description of the purpose of the SAP clearer.
 
Also,  architecturally,  it also makes it possible to reroute the
communications,  e.g. to insert a new
entity that relates to just one SAP and has no effect on the other
such as a new fragmentation/reassembly sublayer.
 
 
Best Regards,
 
Adrian

From: stds-802-21@ieee.org [mailto:stds-802-21@ieee.org] On Behalf Of Phillip Barber
Sent: 04 September 2006 07:07
To: Peretz Feder
Cc: Andrea Francini; STDS-802-21@listserv.ieee.org
Subject: Re: [802.21] SAP semantics

My quick answer is 'Yes'.
 
The SAP is just a focal point for communications in the model.
 
While for any specific message exchange through a SAP the roles of the participants are set, the roles of the participants may change from message exchange-to-message exchange. In one exchange the MS may be a service user. In another exchange the MS may be a service provider.
 
Thanks,
Phillip Barber
Chief Scientist
Broadband Wireless Solutions
Huawei Technologies Co., LTD.
----- Original Message -----
Sent: Sunday, September 03, 2006 8:31 PM
Subject: Re: [802.21] SAP semantics

Phil, as the 802.16g SAP expert, what is your take on the following? 

Can an entity (MIHF 802.21 in this case) that provides services through a SAP (MIH_SAP)
also obtain services (transport and delivery of commands to a remote MIHF)
through the same SAP?

Andrea wrote: I always thought that at the two ends of a SAP the roles of service user and
service provider are fixed. Is this not the case? Can the same entity (the MIHF
in our case) be at the same time a service provider and a service user with
respect to the same SAP?

Peretz Feder


On 9/3/2006 12:56 AM, Andrea Francini wrote:
Hello Everyone,

I have a very basic question from reading the latest 802.21 draft
(P802-21-D01-09):

In section 5.6 (page 29, line 34 through 40) I find the following statement:

"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 commands to another remote (peer) MIHF entity.
Primitives corresponding to all these services described above are within the
scope of MIH_SAP."

The statement indicates that MIHF provides services to a number of upper layers
(MIH users) through the MIH_SAP. Then the statement also seems to indicate (the
wording is not totally explicit) that MIHF can use MIH_SAP to send commands to a
remote MIHF entity.

My question is about the general SAP semantics: 

Can an entity (MIHF in this case) that provides services through a SAP (MIH_SAP)
also obtain services (transport and delivery of commands to a remote MIHF)
through the same SAP?

I always thought that at the two ends of a SAP the roles of service user and
service provider are fixed. Is this not the case? Can the same entity (the MIHF
in our case) be at the same time a service provider and a service user with
respect to the same SAP?

Thanks a lot,

Andrea