Subject: [Megaco] Insufficient bandwidth related query

From: shruti thakral <[email-masked]>
Date: Mon, 8 Oct 2007 13:09:13 +0530

Hi all,

I have a scenario-based query regarding TMAN and b=line of IN SDP. This is 
just my interpretation and I might be wrong.

The Ia Profile document ETSI ES 283 018 v2.0.7 (2007-03) says "the amount 
of required bandwidth for sending packets is expressed using the "b=" line 
of SDP or using the properties of TMAN package. The TMAN package should be 
used in case of variable bit rate traffic." But it doesn't mention 
exactly, furthermore, the kind of linked behaviour expected.

Let us suppose we are using TMAN to set the required bandwidth instead of 
the "b=" line.

TMAN (Traffic Management) package contains properties like
->      Peak data rate (PDR)
->      Sustainable data rate (SDR)
->      Policing (POL)
These properties play a role in QoS support (so does "b=" line of SDP).

PDR specifies peak bytes per second permitted on the stream.
SDR specifies sustainable bytes per second permitted on the stream. 

From what I understand, the byte rate of data being tranferred should be 
between PDR and SDR (these being the max and min thresholds respectively). 

Thus, if traffic crosses the PDR, the MG application should send 
"insufficient bandwidth" error to Toolkit => "I cannot support this much 
traffic with the given bandwidth "

But if the traffic falls below SDR, what would the behaviour be ??
Since this is the minimum traffic promised by the network provider, if at 
some time even if the call parties have traffic less than SDR, it should 
not be an issue, thus (I think) normal behaviour should be expected.

Please comment.

Thanks
Shruti

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From: "Schwarz Albrecht" <[email-masked]>
Date: Mon, 8 Oct 2007 10:57:10 +0200

Shruti,
 
traffic reservation and allocation, and traffic policing, are firstly
separate functions in the Ia profile, knowing that there are semantical
relations.
 
1) use latest draft ETSI ES 283 018 v2.1.0 (2007-09)
Both functions are now in separate sub-clauses. Semantical correlations
are identified.
 
2) traffic policing
Any algorithm for IP byterate policing involves a component for delay
variations, which leads to a bucket component in the algorithm. See also
Draft H.248.53. You should consider the DVT and/or MBS property as well,
and whether you are using a single or a 2-stage policer for sustainable
rates.
 
3) policy action in case of traffic policing
MG application should send "insufficient bandwidth" error 
No. The action is either accept the "whole IP packet", silently reject
or rejection plus statistics update. See H.248.53.
 
4) action of the "traffic reservation and allocation"
MG application should send "insufficient bandwidth" error 
=> possibly yes
 
5) admission control
Further: the "reservation" step is related to an "admission control"
function, which was also subject of discussion a couple of times.
[We are planning more text for clarification, see then 15bTD062
"WI-03098 H.248 Ia Profile V2 - Context/Termination/Stream-level
Admission Control"].
 
The main difference between "admission control" (AC) and "traffic
reservation and allocation" is:
the AC model tries to consider the whole session/call (which is here an
H.248 Context), whereas the later is working more on the level of
individual resource requests.
[A typical BGF AC strategy could be a priority handling of resource
requests: the very first request for a new Context (= first ADD.request
for an IP termination) would be handled with lower priority, but if
accepted, then all subsequent ADD/MOD.requests would get a higher prio.
Such a strategy allows the maximization of the Context completion rate.
Of course, more advanced models will take into account the possible
number of Streams per IP termination. However, the basic model in ES 283
018 is an (IP, IP) Context, which helps already a lot.]
 
-Albrecht

________________________________

	From: shruti thakral [mailto:[email-masked]] 
	Sent: Montag, 8. Oktober 2007 09:39
	To: [email-masked]
	Subject: [Megaco] Insufficient bandwidth related query

	Hi all, 
	
	I have a scenario-based query regarding TMAN and b=line of IN
SDP. This is just my interpretation and I might be wrong. 
	
	The Ia Profile document ETSI ES 283 018 v2.0.7 (2007-03) says
"the amount of required bandwidth for sending packets is expressed using
the "b=" line of SDP or using the properties of TMAN package. The TMAN
package should be used in case of variable bit rate traffic." But it
doesn't mention exactly, furthermore, the kind of linked behaviour
expected. 
	
	Let us suppose we are using TMAN to set the required bandwidth
instead of the "b=" line. 
	
	TMAN (Traffic Management) package contains properties like 
	->        Peak data rate (PDR) 
	->        Sustainable data rate (SDR) 
	->        Policing (POL) 
	These properties play a role in QoS support (so does "b=" line
of SDP). 
	
	PDR specifies peak bytes per second permitted on the stream. 
	SDR specifies sustainable bytes per second permitted on the
stream. 
	
	From what I understand, the byte rate of data being tranferred
should be between PDR and SDR (these being the max and min thresholds
respectively). 
	Thus, if traffic crosses the PDR, the MG application should send
"insufficient bandwidth" error to Toolkit => "I cannot support this much
traffic with the given bandwidth " 
	
	But if the traffic falls below SDR, what would the behaviour be
?? 
	Since this is the minimum traffic promised by the network
provider, if at some time even if the call parties have traffic less
than SDR, it should not be an issue, thus (I think) normal behaviour
should be expected. 
	
	Please comment. 
	
	Thanks 
	Shruti 

	***********************  Aricent-Unclassified
*********************** 
"DISCLAIMER: This message is proprietary to Aricent  and is intended
solely for the use of 
the individual to whom it is addressed. It may contain privileged or
confidential information and should not be 
circulated or used for any purpose other than for what it is intended.
If you have received this message in error, 
please notify the originator immediately. If you are not the intended
recipient, you are notified that you are strictly
prohibited from using, copying, altering, or disclosing the contents of
this message. Aricent accepts no responsibility for 
loss or damage arising from the use of the information transmitted by
this email including damage from virus."