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Schwarz Albrecht | 2 Jun 2008 13:20
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H.248.48 vs Y.2173 (App. II) RTP/RTCP-based performance notification


Hi Geoff,

we did talk about the potential relevance of Y.mpm for RTCP HR/H.248.48
last year.
Y.mpm is now under AAP as Y.2173:
http://www.itu.int/ITU-T/aap/AAPRecDetails.aspx?AAPSeqNo=1738

Please have a look at 
Appendix II - Application scenario 2: RTP/RTCP-based performance
notification
(Is Fig. II.5 from you?)

I didn't review Y.2173 so far, thus I may not comment whether this is
consistent with H.248.48.
At least I would suppose that reference point Mu would be related to
H.248/H.248.48 in case of a reporting interface to ITU-T RACF (via
Rw/Q.3303.2) or ETSI TISPAN RACS (via Ia/ES 283018).

BR, Albrecht
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Agonias, Richard L. (Digitel-GSM | 4 Jun 2008 02:30
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total bandwidth for AMR 12.2

Hi,

 

Hope you can help me. I want to get the bandwidth consumption of the IP Payload on our MGW with an AMR 12.2 codec. What’s the formula?

 

Regards,

 

Richard

 

 

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Schwarz Albrecht | 4 Jun 2008 07:16
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Re: total bandwidth for AMR 12.2

Richard,
 
you may find the general formula in below contribution:
 
AVD-2999 3 H.248 Statistics – Transformation of Traffic-volume related Statistics between Protocol Layers and potential Transformation Rules 
 
See IV.6.3 Bitrate.
You need the AMR framing specifications, i.e.
a) native (=IETF based framing): see RFC 4867
b) 3GPP-specific framing: see FPs for CS domain.
You are interested in the L3 SDU based bitrate.
 
You may transform (under conditions) such kind of traffic metrics between layers, see IV.7. E.g. if you are looking on L3 PDU based values.
 
-Albrecht
 

From: megaco-bounces <at> ietf.org [mailto:megaco-bounces <at> ietf.org] On Behalf Of Agonias, Richard L. (Digitel-GSM)
Sent: Mittwoch, 4. Juni 2008 02:30
To: megaco <at> ietf.org
Subject: [Megaco] total bandwidth for AMR 12.2

Hi,

 

Hope you can help me. I want to get the bandwidth consumption of the IP Payload on our MGW with an AMR 12.2 codec. What’s the formula?

 

Regards,

 

Richard

 

 

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Viresh.Gupta | 4 Jun 2008 08:06
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(no subject)


Hi,
        I am facing trouble in setting up router redundancy for the SoftSwitch ( controls media gateway on H.248). What is the convergance timers for H.248 if any?

Thanks & Regards
Viresh Gupta
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Schwarz Albrecht | 4 Jun 2008 08:30
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router redundancy; RE: (no subject)

Viresh,
 
guess you are considering the H.248 Control Association and/or the underlying (IP or ATM) transport connection (and perhaps changeover, re-registration procedures).
 
Could you indicate correspondent H.248 protocol elements from Annex D and Annex E of H.248.1 you are considering?
 
You know that any general answer is just impossible.
 

From: megaco-bounces <at> ietf.org [mailto:megaco-bounces <at> ietf.org] On Behalf Of Viresh.Gupta <at> Airtel.in
Sent: Mittwoch, 4. Juni 2008 08:06
To: megaco <at> ietf.org
Subject: [Megaco] (no subject)


Hi,
        I am facing trouble in setting up router redundancy for the SoftSwitch ( controls media gateway on H.248). What is the convergance timers for H.248 if any?

Thanks & Regards
Viresh Gupta
This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies and the original message. Any unauthorized review, use, disclosure,dissemination, forwarding, printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful.
The recipient acknowledges that Bharti Airtel Limited or its subsidiaries and associated companies(collectively "Bharti Airtel Limited"),are unable to exercise control or ensure or guarantee the integrity of/overthe contents of the information contained in e-mail transmissions and further acknowledges that any views expressed in this message are those of the individual sender and no binding nature of the message shall be implied or assumed unless the sender does so expressly with due authority of Bharti Airtel Limited. Before opening any attachments please check them for viruses and defects.
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geoff.hunt | 4 Jun 2008 10:41
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Re: H.248.48 vs Y.2173 (App. II) RTP/RTCP-based performance notification

Hi Albrecht, All,

The background to Albrecht's comment is that H.248.48, an H.248 package,
was being developed in ITU-T SG16 to allow transport of RTCP HR metrics
from a Media Gateway to its Media Gateway Controller. Work on H.248.48
is now "on hold" in SG16 pending finding a way forward for RTCP HR in
AVT, see draft-ietf-avt-rtcphr-03 and AVT minutes from Philadelphia.

I didn't contribute to Y.2173 in ITU-T SG13. The material that Albrecht
points out is in an Appendix, which is not normative.

Members of the MEGACO and AVT communities, and who work in organisations
which are members of ITU-T, may wish to review Y.2173 during its AAP
period.

BR
Geoff

-----Original Message-----
From: Schwarz Albrecht [mailto:Albrecht.Schwarz <at> alcatel-lucent.de] 
Sent: 02 June 2008 12:21
To: Hunt,RG,Geoff,DMM R
Cc: megaco <at> ietf.org
Subject: H.248.48 vs Y.2173 (App. II) RTP/RTCP-based performance
notification

 
Hi Geoff,

we did talk about the potential relevance of Y.mpm for RTCP HR/H.248.48
last year.
Y.mpm is now under AAP as Y.2173:
http://www.itu.int/ITU-T/aap/AAPRecDetails.aspx?AAPSeqNo=1738

Please have a look at
Appendix II - Application scenario 2: RTP/RTCP-based performance
notification (Is Fig. II.5 from you?)

I didn't review Y.2173 so far, thus I may not comment whether this is
consistent with H.248.48.
At least I would suppose that reference point Mu would be related to
H.248/H.248.48 in case of a reporting interface to ITU-T RACF (via
Rw/Q.3303.2) or ETSI TISPAN RACS (via Ia/ES 283018).

BR, Albrecht
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Agonias, Richard L. (Digitel-GSM | 5 Jun 2008 08:59
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fax and data over MSC-Server

Hello,

 

Does anyone here implemented fax and data services on the MSC-Server. What’s the standard bandwidth for this?

 

Thanks!

 

 

-richard

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Perz, Gernot | 5 Jun 2008 15:05
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how to identify a "malicious ServiceChange"?

Hello, 

I've recently discusssed the following problem:

In a softswitch environment where an MGC is controlling a big trunking
Gateway, a single ServiceChange looking harmless as the following:

!/1 [192.168.5.210]:2944  T=14905015 
    { C=- { SC=ROOT 
              { SV { MT=Restart , 
                     RE="901 Cold Boot" ,
                     20080503T09011001
                   }
               }
           }
    }

could have disastrous effects if it is sent by the GW (or an attacker
simulating the GW) maliciously. The MGC would assume that all the trunks
went down and have/had to be re-established. As a result of this
Servicechange a lot of Controller-side objects would be logically
released by the MGC, resulting in loss of calls, enforced recoveries on
the MG, etc.

The discussion arose out of the assumption of a misbehaving MG sending
this ServiceChange in a loop (f. I. due to SW problem), but we ended at
the conclusion that even the very first "malicious ServiceChange" could
be "deadly".

Question:
=========

Is there some recommended strategy to detect this sort of "malicious
ServiceChange" on the MGC, like some plausibility check against "normal
MEGACO communication traffic" of the same GW?

F. I., usually one wouldn't assume that this ServiceChange would
plausibly occur mixed into fast sequences of NOTIFYs and transaction
replies from the GW. You would rather expect to observe some
communication problems to the GW before this sort of ServiceChange
occurs.

With kind regards and thanks in advance!

Gernot Perz
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Schwarz Albrecht | 5 Jun 2008 15:44
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Re: how to identify a "malicious ServiceChange"?

There are multiple countermeasures here, like
- H.248 entity authentication
- H.248 message encryption
- H.248 message policing

Guess you know H.Sup7, which is providing some guidelines on each topic.
ITU-T H.Sup7 (ex H.248.CtrlAssoc) "Gateway Control Protocol: Establishment Procedures for the H.248
MGC-MG Control Association" 
http://www.itu.int/md/T05-SG16-080422-TD-PLEN-0480/en

See e.g.
§ 5.6.4	Security: Authentication	
§ 12 		H.248 Control Association: policing of incoming H.248 messages

Masquerading may be addressed by encryption, incorrect SW implementation may demand for message
policing. § 12/H.Sup7 is indicating many message policing options, but of course not exhaustive, just
looking at the simple policy conditions. Underlying assumption are correct H.248 implementations.
If you are faced with incorrect SW implementations, you may need additional, DPI type message polcing
conditions ("Deep H.248 Message Inspection") IMO.

> -----Original Message-----
> From: megaco-bounces <at> ietf.org 
> [mailto:megaco-bounces <at> ietf.org] On Behalf Of Perz, Gernot
> Sent: Donnerstag, 5. Juni 2008 15:06
> To: megaco <at> ietf.org
> Subject: [Megaco] how to identify a "malicious ServiceChange"?
> 
> Hello, 
> 
> I've recently discusssed the following problem:
> 
> In a softswitch environment where an MGC is controlling a big 
> trunking Gateway, a single ServiceChange looking harmless as 
> the following:
> 
> !/1 [192.168.5.210]:2944  T=14905015 
>     { C=- { SC=ROOT 
>               { SV { MT=Restart , 
>                      RE="901 Cold Boot" ,
>                      20080503T09011001
>                    }
>                }
>            }
>     }
> 
> could have disastrous effects if it is sent by the GW (or an 
> attacker simulating the GW) maliciously. The MGC would assume 
> that all the trunks went down and have/had to be 
> re-established. As a result of this Servicechange a lot of 
> Controller-side objects would be logically released by the 
> MGC, resulting in loss of calls, enforced recoveries on the MG, etc.
> 
> The discussion arose out of the assumption of a misbehaving 
> MG sending this ServiceChange in a loop (f. I. due to SW 
> problem), but we ended at the conclusion that even the very 
> first "malicious ServiceChange" could be "deadly".
> 
> Question:
> =========
> 
> Is there some recommended strategy to detect this sort of 
> "malicious ServiceChange" on the MGC, like some plausibility 
> check against "normal MEGACO communication traffic" of the same GW?
> 
> F. I., usually one wouldn't assume that this ServiceChange 
> would plausibly occur mixed into fast sequences of NOTIFYs 
> and transaction replies from the GW. You would rather expect 
> to observe some communication problems to the GW before this 
> sort of ServiceChange occurs.
> 
> With kind regards and thanks in advance!
> 
> Gernot Perz
> 
> _______________________________________________
> Megaco mailing list
> Megaco <at> ietf.org
> https://www.ietf.org/mailman/listinfo/megaco
>
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Schwarz Albrecht | 10 Jun 2008 11:23
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supplementary media formats; RE: [ams-design] Granularity of micro-applications

Paul,
 
we got a similar discussion for H.248.
We did introduce the notion of "supplementary media formats", see
H.248 Sub-series Implementors’ Guide (Rev.)
 
-Albrecht
 

7.1.7.1.3   ReserveValue

...

Note:  A single set of property values may consist of a single media type (e.g. audio or video) related media format complemented by a list of supplementary media formats. Supplementary media formats are for example:

·        Comfort noise ([IETF RFC 3389]),

·        RTP Payload for DTMF digits, telephony tones and telephony signals ([IETF RFC 4733]),

·        Voiceband data (VBD) services (according to [ITU-T V.152]),

·        or other auxiliary media (e.g. inband signaling) associated to the main media flow.

 

...

From: ams-design-bounces <at> lists.packetizer.com [mailto:ams-design-bounces <at> lists.packetizer.com] On Behalf Of Robert Jongbloed
Sent: Dienstag, 10. Juni 2008 02:56
To: ams-design <at> lists.packetizer.com
Subject: Re: [ams-design] Granularity of micro-applications

My $0.02

 

The apps should be logically distinct entities, always being from the “user” perspective. While the line could be blurred as in DTMF (they are tones so aren’t they voice?) it is still a distinct function. A Bluetooth earpiece could do voice but not DTMF, and the DTMF for the same call is done by a separate entity, the handset. So I think there should be separate “uii_app” and “fax_app”.

 

Dealing with things like RFC2833 means there may need to be a multiplexing capability (somehow) at the app to container boundary. Or perhaps some mechanism for peer to peer communication between apps.

 

 

Robert Jongbloed

OPAL/OpenH323 Architect and Co-founder.

 

From: ams-design-bounces <at> lists.packetizer.com [mailto:ams-design-bounces <at> lists.packetizer.com] On Behalf Of Paul E. Jones
Sent: Tuesday, 10 June 2008 8:42 AM
To: ams-design <at> lists.packetizer.com
Subject: [ams-design] Granularity of micro-applications

 

Folks,

 

One of the things that has been sitting in the back of my mind is the granularity of micro-applications.  Originally, I had proposed that we might have a “voice_app” and a “video_app”, for example.  But, what constitutes a “voice_app”?  Does that include DTMF or would that be separate?  (Given that we would need to multiplex DTMF within the audio path – due to the unfortunate use of RFC 2833 – it might make sense for DTMF to be a function of the voice_app.)

 

But, what about fax?  Fax could arguably be separated entirely.  In fact, I’m wondering if we ought to solicit the help of Q14/16 in the design of a fax_app that might be used in AMS.

 

The thinking is that a typical PSTN GW might advertise that it has the voice_app and fax_app and modem_app applications.  These would not be operating in parallel, obviously.  So, when a fax tone is detected, a transition could be made from the voice_app to the fax_app.

 

Does that kind of separation make sense, or do you think that the fax functionality ought to be defined as a part of the voice_app?

 

My thinking is that by separating the voice_app and fax_app, we not only define a cleaner and simpler voice_app, but it would also allow an AMS user to walk up to a fax machine, for example, and receive a fax while talking on the phone, as the fax_app would be invoked in parallel.

 

Paul

 

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