[asterisk-dev] Native Bridging: terminology

[Russell Bryant]

On 03/18/2010 10:25 AM, Mark Michelson wrote:
> Klaus Darilion wrote:
>> Hi!
>>
>> What is the exact meaning of "native bridging"? For example I know with
>> DAHDI it means direct bridging on the hardware. But what about from one
>> DAHDI interface card to another DAHDI card? Are there some optimizations
>> that the audio stays within the kernel module or is it always send via
>> Asterisk's core?
>>
>> Or in case of a SIP-to-SIP call with canreinvite=no. Will there be some
>> optimizations that audio stays within the rtp module or will it be sent
>> via Asterisk's core? If there are such optimizations - is this called
>> direct bridging or is direct bridging the RTP exchange between clients
>> directly using canreinvite=yes (which I would not call direct bridging
>> but "offload" or "bypass")? Or is this the "external native bridge"?
>>
>> thanks
>> klaus
>>
>
> The term "native bridge" is a bit overloaded in Asterisk. On the surface, it
> simply means that the two legs of a call have the same channel->tech->bridge
> function.
>
> I can't speak for DAHDI, but within SIP, native bridging has two subcategories.
> One, typically referred to as "SIP native bridging" is used when reINVITEs are
> enabled. The endpoints send their media directly to one another. The other
> subcategory is called "Packet 2 Packet" or "P2P" bridging. If reINVITEs are not
> enabled, but there are also no features that require the Asterisk core to be in
> the voice path, then the bridging will be done at the RTP layer of Asterisk.

There is a section on the architectural concept of bridging (including 
native bridging) in include/asterisk/doxygen/architecture.h.  If anyone 
would like to help expand upon this text, I would appreciate it.  :-)

-- 
Russell Bryant
Digium, Inc.  |  Engineering Manager, Open Source Software
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