Error in H.323v3 ASN.1

[Paul E. Jones]

Paul,

The problem with this simpler approach to deprecating the fields is that
there will still be v2 entities that expect to see the aliasesInconsistent
field and there may be v3 entities out there that assume a different field
is there and things will be broken between those endpoints.

Perhaps it might be less of an impact, though...

Paul

----- Original Message -----
From: "Paul Long" <Plong at SMITHMICRO.COM>
To: "Mailing list for parties associated with ITU-T Study Group 16"
<ITU-SG16 at mailbag.cps.intel.com>
Cc: <h323implementors at imtc.org>; <h323implementors at pulver.com>
Sent: Thursday, October 05, 2000 2:08 PM
Subject: RE: Error in H.323v3 ASN.1


> Paul,
>
> I just checked, and we are shipping v3 EPs. I agree that there are
probably
> many more v2 entities than v3 entities, and therefore if we have to break
> one, we should break the one which will have the least impact on the
market.
>
> To minimize the impact this will have on interoperability, however, let's
> don't simply move the reasons around. Instead, lets deprecate the current
> routeCallToSCN and aliasesInconsistent reasons using the following
syntaxes
> in IGv3 and H.225.0v4.
>
> Proposed IGv3 syntax
>
> AdmissionRejectReason ::= CHOICE
> {
> calledPartyNotRegistered NULL, -- cannot translate address
> invalidPermission NULL, -- permission has expired
> requestDenied NULL, -- no bandwidth available
> undefinedReason NULL,
> callerNotRegistered NULL,
> routeCallToGatekeeper NULL,
> invalidEndpointIdentifier NULL,
> resourceUnavailable NULL,
> ...,
> securityDenial NULL,
> qosControlNotSupported NULL,
> incompleteAddress NULL,
>
> -- changes start here:
> deprecatedAliasesInconsistent NULL, -- do not use
> deprecatedRouteCallToSCN SEQUENCE OF PartyNumber, -- do not use
> callCapacityExceeded NULL, -- destination has exceeded call capacity
> aliasesInconsistent NULL, -- multiple aliases in request identify distinct
> people
> routeCallToSCN SEQUENCE OF PartyNumber
> }
>
>
> Proposed H.225.0v4 syntax
>
> AdmissionRejectReason ::= CHOICE
> {
> calledPartyNotRegistered NULL, -- cannot translate address
> invalidPermission NULL, -- permission has expired
> requestDenied NULL, -- no bandwidth available
> undefinedReason NULL,
> callerNotRegistered NULL,
> routeCallToGatekeeper NULL,
> invalidEndpointIdentifier NULL,
> resourceUnavailable NULL,
> ...,
> securityDenial NULL,
> qosControlNotSupported NULL,
> incompleteAddress NULL,
>
> -- changes start here:
> deprecatedAliasesInconsistent NULL, -- do not use
> deprecatedRouteCallToSCN SEQUENCE OF PartyNumber, -- do not use
> exceedsCallCapacity NULL, -- destination does not have the capacity for
> this call
> aliasesInconsistent NULL, -- multiple aliases in request identify distinct
> people
> routeCallToSCN SEQUENCE OF PartyNumber,
> collectDestination NULL,
> collectPIN NULL
> }
>
> I assume we can change both because neither are Decided and these are true
> irreconcilable errors in the documents, correct? Here are the specifics:
We
> rename the old reasons to "deprecate*", add the new ones after
> callCapacityExceeded/exceedsCallCapacity, and then in the text of IGv3 and
> H.225.0v4 say that the old ones shall not be transmitted and if received
> shall be treated like undefinedReason. Otherwise, a receiver would have to
> parse the AdmissionReject message differently depending on the version of
> the transmitter. We, Smith Micro, can actually do that with our ASN.1
parser
> but I'm guessing that most implementations cannot. Maybe we should even
> change the type of deprecatedRouteCallToSCN to NULL so that the ASN.1 PER
> parser would simply skip over the contents via the encapsulating open
type.
> I know that our parser would do this. Would others?
>
> v1 implementations won't have a problem, because they would ignore this
> reason, anyway, but we could encourage v2 implementations to treat
> aliasesInconsistent like undefinedReason since they won't know if it is
> aliasesInconsistent from a v2 EP or some other extended choice from a v3+
> EP.
>
> Paul Long
> Smith Micro Software, Inc.
> --------------------------------------------------------------------------
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