Hi, Reading http://www.asteriskguru.com/tutorials/bri.html , it seems PtP is the way to connect businesses but if you read http://public.swbell.net/ISDN/connect.html you would think the opposite. Can anyone elaborate a bit PtP or PtmP respective advantages ? Cheers -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20080929/70293357/attachment.htm
On Mon, Sep 29, 2008 at 01:26:10PM +0200, Olivier wrote:> Hi, > > Reading http://www.asteriskguru.com/tutorials/bri.html , it seems PtP is > the way to connect businesses but if you read > http://public.swbell.net/ISDN/connect.html you would think the opposite. > > Can anyone elaborate a bit PtP or PtmP respective advantages ?With analog phone lines you can have multiple handsets share the same physical line. That is: multiple FXSs and one FXS. Only one talk at a time. PtMP is an attempt to preserve that feature: multiple CPE units can share the same physical connection to a network unit. Only up to two talks at a time. Another nice feature of analog handsets is that they are powered from the FXS. Likewise BRI phones can be powered from the network unit. Those two features are quite nice when your equipment is a simple phone. They are mostly useless for a PBX: your PBX will have an independent power source anyway. And will most likely want to handle all the line by itself. The problem is that those features come with a price tag of complexity. For instance, many providers want to save power and hence drop the (even layer 1) connection to a ptmp bri cpe unit because it is probably an isdn phone that takes some precious power (some 25V, IIRC). As a result, your PBX cannot really tell if the red alert it has is faked or not. -- Tzafrir Cohen icq#16849755 jabber:tzafrir.cohen at xorcom.com +972-50-7952406 mailto:tzafrir.cohen at xorcom.com http://www.xorcom.com iax:guest at local.xorcom.com/tzafrir
Philipp Kempgen
2008-Sep-29 12:14 UTC
[asterisk-users] OT - Avantages of ISDN PtP and PtmP
Olivier schrieb:> Reading http://www.asteriskguru.com/tutorials/bri.html , it seems PtP is > the way to connect businesses but if you read > http://public.swbell.net/ISDN/connect.html you would think the opposite.That's not true, although "multipoint" sounds better than just one "point". :-) PtMP: Usually you connect your devices (phones etc.) directly to the line (although you could connect a PBX). Each of the phones has a totally different number. PtMP is what home users get unless they request something else. PtP: You connect just one device which is your PBX. You get a block of numbers (xx / xxx / xxxx / ...). The nice thing is that you can easily map these external DID numbers to internal extensions, i.e. ......xx -> xx More expensive than PtMP. btw: _PRI_ is always PtP. Philipp Kempgen -- http://www.das-asterisk-buch.de - http://www.the-asterisk-book.com Amooma GmbH - Bachstr. 126 - 56566 Neuwied -> http://www.amooma.de Gesch?ftsf?hrer: Stefan Wintermeyer, Handelsregister: Neuwied B14998 --
2008/9/29 Olivier <oza-4h07 at myamail.com>:> Hi, > > Reading http://www.asteriskguru.com/tutorials/bri.html , it seems PtP is > the way to connect businesses but if you read > http://public.swbell.net/ISDN/connect.html you would think the opposite. > > Can anyone elaborate a bit PtP or PtmP respective advantages ? >IMHO: PtMP should only be used if you have Multiple devices connected to your ISDN (Hence the Multiple part in its name) - This setup means that for each outgoing call, the calling device has to negotiate almost from scratch, access to a B-channel, and every inbound call is sent (broadcast) to every connected device to give it the chance to grab it. This is an almost compeletly chaotic and stateless environment (I know, of course there IS state, just a lot less of it). PtP on the other hand is stateful - The one device negotiates a connection when it comes up, and monitors the line constantly, so it knows if (for example) the line goes down. Calls in both directions are sent to the one known endpoint, directly addressed to a B-channel that it already knows should be available. Also, if a call comes in to an unrecognised DDI/address, PtMP can only time-out (no-one grabs the call) where PtP can dynamically know that the call is rejected and handle it "properly" For 99% of Asterisk installs, where Asterisk is managing/routing all calls on a line, PtP is going to be the right choice. Cheers, Steve