[Serusers] About B2BUA

[chang hui]

Jiri,

Thanks for your explanation, and let me know the architecture drawback of the B2BUA.
Since we have no way to choose other means to implement pre-paid, we have to go along with B2BUA in a short term.
Could you give me any advise how to implement B2BUA based on SER and estimate the work we should do?
Could you give me a performance estimate?

Best Regards and Thanks.


Chang Hui
-----Original Message-----
From: Jiri Kuthan [mailto:jiri at iptel.org]
Sent: Saturday, January 04, 2003 8:29 PM
To: chang hui; serusers at lists.iptel.org
Subject: RE: [Serusers] About B2BUA

Hello,

I see -- prepaid scenarios are indeed difficult without a B2BUA.
There has been a proposal few times to use session timer (a proxy
looks at ballance and attaches a hint to SIP requests indicating
when a call should terminate), but the work has not been pursued.

You may find a discussion of B2BUA architectural drawbacks on the
SIP mailing list, selected postings are at http://www.iptel.org/info/trends/#b2bua.
imho, the most compelling issue is that of robustness and scalability.
A b2bua needs to keep track of all current calls. A broken b2bua affects
signaling for all existing calls.

Basically, a B2BUA is simply two UAs glued together. It accepts
transactions as a server, and initiates client transactions
based on them. It keeps dialog state (callid, cseqs, etc.) and
may initiate in-dialog transactions on its own (like the BYE
transaction in which you are interested).

It is doable to implement a B2BUA on top of ser, but it would
cost quite some development effort. Particularly, it would take
dialog maintenance (better with persistency so that signaling
does not get broken on reboot). We  can provide guidanance to
volunteers willing to go through this exercise.

-Jiri

At 02:28 AM 1/4/2003, chang hui wrote:
>Jiri,
>
>Thanks for your prompt response.
>We want to implement a pre-paid system in which once subscriber's balance is depleted, the dialog could be torn in time. However other Proxy or other elements could not take part in the call, they could not send a BYE to caller directly. It's the why we consider B2BUA.
>We project to build a B2BUA to support voice/video/IM at first stage, and support other SIP based services as they emerged.
>However, I just noticed the definition of B2BUA in 2543-bis04 in several sentences,  there has no other analysis on performance, reliability, limitations and how to implement it. So, I hope to get help from the society.
>Thanks for your help again.
>
>Koalas
>
>-----Original Message-----
>From: Jiri Kuthan [mailto:jiri at iptel.org]
>Sent: Friday, January 03, 2003 11:06 PM
>To: chang hui; serusers at lists.iptel.org
>Subject: Re: [Serusers] About B2BUA
>
>Hello,
>
>ser is not a B2BUA -- it can act as proxy, redirect, transactional UAS
>or registrar. These modes make a vast majority of network scenarios
>happy without a need to use a B2BUA. Which is good, because B2BUAs
>inherently have certain scalability, reliability and security limitations.
>
>Is there a particular reason why you would like to use a B2BUA?
>
>-Jiri
>
>At 08:00 AM 1/3/2003, chang hui wrote:
>>Hi All,
>>
>>I am newbie of this field, thanks everyone help me.
>>I am interesting in B2BUA, however, except some brief defination in 3261, I could not find any further defination or how to implement about B2BUA, I noticed that SER could be implemented as a B2BUA, where can I find some implementation? or where can I get any description?
>>
>>Koalas
>>_______________________________________________
>>Serusers mailing list
>>serusers at lists.iptel.org
>>http://lists.iptel.org/mailman/listinfo/serusers
>
>--
>Jiri Kuthan            http://iptel.org/~jiri/

--
Jiri Kuthan            http://iptel.org/~jiri/