Subject: RE: [Mipshop] Some comments on draft-faccin-mih-infoserv-01

From: [email-masked]
Date: Fri, 21 Oct 2005 16:09:38 -0500

Hi Dirk,
You bring up very interesting points for discussion. I can address some
comments as a 802.21 participant.

>1) I understand that the draft presents transport protocol 
>requirements. 
>But do we think that the use cases and general functional 
>requirements are complete? For example, there seems to be the 
>implicit assumption that an IS will always be accessed in an 
>interactive query/response-style. (This is what the 802.21 
>document is proposing). 
>Now, for a non-realtime IS for distributing information about 
>available network services in a certain network-topological or 
>geographical scope, one could also consider 
>multicast/broadcast distribution.

You are essentially referring to a push IS model leaving out the
broadcast/muticast part. This has come up for discussion but there were
no compelling use cases involving wireless terminals. (But who knows
this may change if there is interest for it)Broadcast/multicast
discussion never came up because the IS server may not be located in the
network where mobile is presently registered.  Please bear in mind that
the scope of 802.21 is only handover related, correspondingly the IS
services are meant for use in handovers but not to simply distribute
network services information.

>Now, I think these scenarios imply additional requirements for 
>uniquely identifying and authenticating service descriptions. 
>For example, the same service description may be available 
>from different ISs, and I want to make sure that I can 
>uniquely identify it. This is especially important when we 
>consider periodic transmission, e.g., in multicast 
>distribution scenarios.

This requirement is handled in the security part for either mutual
authentication of the end nodes. The multiplicity of the same/similar
information is handled via network policies at the terminal and network
provisioning. But, there may be use cases that are considered in 802.21
or in the draft. It would certainly useful to discuss them here or on
the 802.21 ML.

>I have another general comment (not on the Internet Draft 
>itself): I am not sure that it is a useful approach to 
>separate the IS content discussion from the IS transport 
>discussion, i.e., by saying the IETF is to develop an IP-based 
>transport for the IEEE 802.21 IS format.

Good point. I don't think 802.21WG is planning to provide a final format
over IP based transport. The format will be discussed here based on
reference from 802.21 specification or other documents.

Regards,
Srini

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From: [email-masked]
Date: Fri, 21 Oct 2005 16:40:55 -0500

Some responses to your questions ... 

>I think these are valid uses of IS. But they are something 
>else than predictive handover.
>
>IMO, the first questions we need to answer should be:
>
>1) Which use case are we addressing here (predictive handover vs.
>    "broader use")?
>2) Does this relate to 802.21 or not?

We are addressing both but perhaps not the parameter you refer to under
broader use. Payments and their options have been discussed but not
considered as something that can be disclosed easily by the service
provider and automated, without user intervention. Hence, in 802.21 the
requirements are to the extent to say whether the network is free or
'not free'.

>3) If "broader use" is considered in-scope: how does broader-use fit to
>    predictive handover, e.g., is there any use for a common 
>approach for
>    information representation and transport protocols.

IMO, any information relevant to a handover decision can be incorporated
in the IS mechanism. That includes all of network identification,
security mechanisms supported, services supported etc. It would bring
some focus by limiting the broader use to handover relevant information.

>Best regards,
>Dirk