is there any difference between IMUX and Q/BRI ?

[cutechap25]

is there any difference between IMUX and Q/BRI ?

Thanks in adv.

[trapehzoid]

need to be more descriptive. Difference in what?

An IMUX is a term used to describe a device that 'muxs' a larger data stream over several individual smaller channels and back again. In the VTC world, this is almost always referring to getting one larger call using several ISDN lines. For instance, getting a 384kbs call out of 6 individual 64kbs ISDN calls. These used to be stand-alone units, but are now integrated into almost every piece of VC gear that interfaces to ISDN.

A Q/BRI would be referring to a 4 x BRI interface of some sort most likely.. but I have no idea what you are referring to exactly. Last piece of gear to use that type of terminology I think was a Madge device.

And in the case of Madge, yes, a MUX card and a QBRI card were very different :) QBRI was an ISDN interface card.. and if memory serves, the MUX card simply allowed the unit to do bonding for ISDN (loosely). If my memory serves.

What exactly are you trying to figure out?

[Oliver Black]

A QBRI card is a flavor of an IMUX card that aggregates four BRI ISDN lines into one fat data stream. QBRI is the physical interface. IMuxing (inverse multiplexing) is the process of putting that data onto the four separate lines and also receiving data from the four separate lines and putting them into a single data stream for the VC system to deal with. An IMUX can have different interfaces,1,2,3,4, or more BRI's, PRI's, etc.

[MACC the AVCOtek]

A Q/BRI would be referring to a 4 x BRI interface of some sort most likely.. but I have no idea what you are referring to exactly. Last piece of gear to use that type of terminology I think was a Madge device.


The Polycom VSX7000 utilizes a Q/BRI module to interface with ISDN. This module works just as Oliver Black describes - plug up to 4 BRIs into the box (which, incidentally, plugs into the subwoofer), configure the codec correctly (numbers and SPIDs) and make ISDN calls up to 512K.

[George]

Well if the Tandberg 1000 has 3 ISDN ports does that make it a Tri/Bri? :D

[trapehzoid]

my point remains the same.. these terms need more context to be meaningful :)

[Glen Sykes]

my point remains the same.. these terms need more context to be meaningful :)


Certainly does, I have a QBRI IMUX from Polycom, i also have a RAS gateway with a QBRI interface. QBRI only means that it has 4 x BRI interfaces.

IMUXes on the other hand can come with all sorts of interfaces, tri-bri, quad-bri, 12XBRI, PRI.

At a guess, this might be a question relating to BONDING vs H.221, in which case in a nutshell.....

BONDING: This is where channels are aggregated via the dialing of a single number. The IMUX at the remote end is configured so that it knows the numbers of the circuits it is attached to. When accepting the call, the IMUX informs the dialer of the remaining numbers required to dial based on the interface that the call came in on. Once the remaining channels are dialed, frame alignment is established across all the channels dialed. This means that the relative delay between the channels must be within a defined parameter (the actual time escapes me for the moment). This is one of the reasons you will see downspeeding at call setup, as a channel simply takes a route that is too slow to be 'bonded'.

H.221: This is where the dialer dials all the numbers for the far end, so for a 6 channel call, the dialer dials 6 seperate numbers. This is in fact the only mandatory standard for call setup in the H.320 standard, even though BONDING is by far the most popular. 6 Channel H.221 calls have cause tech support engineers no end of problems over the years, particularly with some Sony endpoints that didn't support BONDING at all. In H.221, each 64k channel is individually framed, meaning that generally H.221 calls were more resilient, but more of a pain in the arse to set up!

Hope this answered the question, if it didn't hope you found it useful anyway!!!

Cheers,

Glen

[robertk]

Well if the Tandberg 1000 has 3 ISDN ports does that make it a Tri/Bri? :D

Sure, the same way the Picturetel Venue was sold with a Tri-Bri card.


//Robert

[sdevoy]

What's a BI-BRI then? Or is that a question dor another forum!

[Glen Sykes]

What's a BI-BRI then? Or is that a question dor another forum!


You made that up silly ;)