Subject: Queries in v12

From: Prashant Jain <[email-masked]>
Date: Thu, 25 Nov 1999 01:52:40 +0530

hi tom, Brian,

We have some queries:

1.  As per ANNEX D which discusses Application Level Framing, an entity (MG/MGC)
,which generates a Response for a transaction request,  shall store the Response
for LONG TIMER seconds. Also it is stated that this LONG TIMER value calculation
should take into account the maximum number of retries, maximum repetition timer
and the maximum propagation delay.

Now the Qs. is what does "maximum propagation delay of  a packet in the network"
actually means. Does this parameter relates to "Time to Live" field in IP
datagram header since TTL field denotes the maximum time for which a IP
datagram can stay in the network.
If this is not so, then what does it really represents and how it can be used to
determine the LONG TIMER value ?

2. In section 7.2.8, there is a field called "profile" in the Service Change
Descriptor. What is the actual significance of profile parameter and when it
shall be used between MG and MGC.

3. As per the ABNF grammar of MEGACO, there is a field "Time Notation"
associatied with the Transaction Pending Reply.
The query is what is the significance of attaching Time Stamp with Transaction
Pending. Can the receiver of the Pending Response estimate something based on it
for e.g., remote entity normalExecutionTime etc.

4. As per section 8.2.3, MGC shall set two properties, namely,
normalMGExecutionTime and normalMGCExecutionTime. Earlier in the mailing list it
was said that these shall be present in the ROOT package. But the ABNF grammar
allows the properties to be specified only in a Descriptor, as signified by the
property param field present in the Local Control Descriptor, etc.
So the Qs. is that if MGC wants to set the above properties at ROOT
terminationID, we would require to have one more Descriptor called  root
Descriptor in the list. Is it correct?

We would appreciate if you reply.

Regards,

Prashant Jain

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From: "Rosen, Brian" <[email-masked]>
Date: Wed, 24 Nov 1999 16:45:06 -0500

> datagram can stay in the network.
I suppose you could consider TTL, but I think you would have
a hard time interpreting a millisecond value from the TTL
field.

> determine the LONG TIMER value ?
I'd use a provisioned initial guess.  I might be able to use some
experience data (response time I observed over time) to
update it.

> shall be used between MG and MGC.
It is expected that various groups (including, but not
limited to IETF and/or ITU) will define various profiles.
For example, the Multiservice Switching Forum anticipates
it would define a profile for a trunk gateway.

Profiles would include things like the minimum packages that must
be implemented.  It might specify transport above the
requirements of the protocol (that is, specify the gateway
must implement a transport that is listed as optional in
the protocol).

It could have things like naming conventions for terminationIDs.

> for e.g., remote entity normalExecutionTime etc.
Sounds like a left over from a prior definition of Pending.
I'll take a look at it for possible fixing.

> Descriptor in the list. Is it correct?
No, the Root termination is a termination with the terminationID= root.  It
has a TerminationState.  Root properties would be
defined in the TerminationState descriptor of the root.

So one might say:
Modify=Root{TerminationState{normalMGCExecutionTime=250}}

To read normalMGExecutionTime, one might use:
AuditValue=Root{Media}

I don't think root has a localControl, but if someone
comes up with a stream specific root property maybe it could.

Brian

---

From: Prashant Jain <[email-masked]>
Date: Thu, 25 Nov 1999 10:23:00 +0530

hi brian,
Thanks for the reply.

Our one more doubt is below marked by <PJ>.

** <PJ> **  Ok fine. Let us say we put initial guess for the value of network
propagation delay. But one Qs. is still unanswered that how to calculate the
value of LONG TIMER. Can we calculate it approximately as follows:

LONG TIMER = (Max. Num. Retries + 1) * Max. Retransmit Timer + Max. Network
Propagation Delay.

The above calculation is based on the assumption that for each Retransmission,
maximum value of Retransmit Timer (maximum RTO value) is taken in order to have
worst case estimate. The Max. network delay has been added assuming that the
last retransmission made by the sender can stay alive in the network for the
duration given by Max. network propagation delay and could produce duplicate
copies of the transaction. It is also presumed that the value of the
Retransmission time out (RTO) for the last retry is small as compared to the
max. network propagation delay. Otherwise, the above equation is modified to

LONG TIMER = (Max. Num. Retries + 1) * Max. Retransmit Timer + (Max. Network
Propagation Delay - Last RTO).

Does the above estimation sound correct or do we have some wrong understanding
regarding LONG TIMER values.

Regards,

Prashant Jain