221 lines
8.5 KiB
Text
221 lines
8.5 KiB
Text
<!-- $Id: isdn.sgml,v 1.15 1998-08-09 14:27:37 wosch Exp $-->
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<!-- The FreeBSD Documentation Project -->
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<sect><heading>ISDN<label id="isdn"></heading>
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<p><em>Last modified by &a.wlloyd;</em>.
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<p>A good resource for information on ISDN technology and hardware is
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<url url="http://alumni.caltech.edu/~dank/isdn/" name="Dan Kegel's
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ISDN Page">.
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A quick simple roadmap to ISDN follows:
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<itemize>
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<item>If you live in Europe I suggest you investigate the ISDN card
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section.
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<item>If you are planning to use ISDN primarily to connect to the
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Internet with an Internet Provider on a dialup non-dedicated basis, I
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suggest you look into Terminal Adapters. This will give you the most
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flexibility, with the fewest problems, if you change providers.
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<item>If you are connecting two lans together, or connecting to the
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Internet with a dedicated ISDN connection, I suggest you consider the
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stand alone router/bridge option.
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</itemize>
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<p>Cost is a significant factor in determining what solution you will
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choose. The following options are listed from least expensive to most
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expensive.
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<sect1><heading>ISDN Cards</heading>
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<P><em>Contributed by &a.hm;</em>.
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<P>This section is really only relevant to ISDN users in countries where
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the DSS1/Q.931 ISDN standard is supported. </P>
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<P>Some growing number of PC ISDN cards are supported under FreeBSD 2.2.x
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and up by the isdn4bsd driver package. It is still under development but
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the reports show that it is successfully used all over Europe.</P>
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<P>The latest isdn4bsd version is available from
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<url url="ftp://isdn4bsd@ftp.consol.de/pub"
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name="ftp://isdn4bsd@ftp.consol.de/pub">
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The main isdn4bsd ftp site (You have to log in as user isdn4bsd , give
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your mail address as the password and change to the "pub" directory.
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Anonymous ftp as user "ftp" or "anonymous" will NOT
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(!) give the desired result ! ).</P>
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<P>Isdn4bsd allows you to connect to other ISDN routers using either IP
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over raw HDLC or by using synchronous PPP. A telephone answering machine
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application is also available.</P>
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<P>Many ISDN PC cards are supported, mostly the ones with a Siemens ISDN
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chipset (ISAC/HSCX), support for other chipsets (from Motorola, Cologne
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Chip Designs) is currently under development. For an up-to-date list of
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supported cards, please have a look at the
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<url url="ftp://isdn4bsd@ftp.consol.de/pub/README" name="README">
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file.</P>
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<P>In case you are interested in adding support for a different ISDN protocol,
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a currently unsupported ISDN PC card or otherwise enhancing isdn4bsd, please
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get in touch with <url url="mailto:hm@kts.org" name="hm@kts.org">.</P>
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<P>A majordomo maintained mailing list is available. To join the list,
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send mail to <TT><url url="mailto:majordomo@FreeBSD.ORG" name="majordomo@FreeBSD.ORG"></TT>
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and specify: </P>
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<p><tt>subscribe freebsd-isdn</tt></p>
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<P>In the body of your message. </P>
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<sect1><heading>ISDN Terminal Adapters</heading>
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<p>Terminal adapters(TA), are to ISDN what modems are to regular phone
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lines.
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<p>Most TA's use the standard hayes modem AT command set, and can be
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used as a drop in replacement for a modem.
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A TA will operate basically the same as a modem except connection and
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throughput speeds will be much faster than your old modem. You will
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need to configure <ref id="ppp" name="PPP"> exactly the same as for a
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modem setup. Make sure you set your serial speed as high as possible.
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The main advantage of using a TA to connect to an Internet Provider is
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that you can do Dynamic PPP. As IP address space becomes more and more
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scarce, most providers are not willing to provide you with a static IP
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anymore. Most standalone routers are not able to accommodate dynamic IP
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allocation.
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TA's completely rely on the PPP daemon that you are running for their
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features and stability of connection. This allows you to upgrade easily
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from using a modem to ISDN on a FreeBSD machine, if you already have PPP
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setup. However, at the same time any problems you experienced with the
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PPP program and are going to persist.
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If you want maximum stability, use the kernel <ref id="ppp" name="PPP">
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option, not the user-land <ref id="userppp" name="iijPPP">.
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<p>The following TA's are know to work with FreeBSD.
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<itemize>
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<item>Motorola BitSurfer and Bitsurfer Pro
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<item>Adtran
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</itemize>
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Most other TA's will probably work as well, TA vendors try to make sure
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their product can accept most of the standard modem AT command set.
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The real problem with external TA's is like modems you need a good
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serial card in your computer.
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You should read the <ref id="uart" name="serial ports"> section in the
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handbook for a detailed understanding of serial devices, and the
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differences between asynchronous and synchronous serial ports.
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A TA running off a standard PC serial port (asynchronous) limits you to
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115.2Kbs, even though you have a 128Kbs connection. To fully utilize
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the 128Kbs that ISDN is capable of, you must move the TA to a
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synchronous serial card.
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Do not be fooled into buying an internal TA and thinking you have
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avoided the synchronous/asynchronous issue. Internal TA's simply have a
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standard PC serial port chip built into them. All this will do, is save
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you having to buy another serial cable, and find another empty
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electrical socket.
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A synchronous card with a TA is at least as fast as a standalone router,
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and with a simple 386 FreeBSD box driving it, probably more flexible.
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The choice of sync/TA vs standalone router is largely a religious
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issue. There has been some discussion of this in the mailing lists. I
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suggest you search the <url url="../search/search.html"
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name="archives"> for the complete discussion.
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<sect1><heading>Standalone ISDN Bridges/Routers</heading>
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<p>ISDN bridges or routers are not at all specific to FreeBSD or any
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other operating system. For a more complete description of routing and
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bridging technology, please refer to a Networking reference book.
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In the context of this page, I will use router and bridge
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interchangeably.
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<p>As the cost of low end ISDN routers/bridges comes down, it will
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likely become a more and more popular choice. An ISDN router is a small
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box that plugs directly into your local Ethernet network(or card), and
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manages its own connection to the other bridge/router. It has all the
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software to do PPP and other protocols built in.
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A router will allow you much faster throughput that a standard TA, since
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it will be using a full synchronous ISDN connection.
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The main problem with ISDN routers and bridges is that interoperability
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between manufacturers can still be a problem. If you are planning to
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connect to an Internet provider, I recommend that you discuss your needs
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with them.
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<p>If you are planning to connect two lan segments together, ie: home
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lan to the office lan, this is the simplest lowest maintenance
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solution. Since you are buying the equipment for both sides of the
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connection you can be assured that the link will work.
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For example to connect a home computer or branch office network to a
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head office network the following setup could be used.
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<em>Branch office or Home network</em>
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Network is 10 Base T Ethernet. Connect router to network cable with
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AUI/10BT transceiver, if necessary.
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<verb>
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---Sun workstation
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---FreeBSD box
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---Windows 95 (Do not admit to owning it)
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Standalone router
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ISDN BRI line
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</verb>
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If your home/branch office is only one computer you can use a twisted
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pair crossover cable to connect to the standalone router directly.
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<em>Head office or other lan</em>
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Network is Twisted Pair Ethernet.
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<verb>
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-------Novell Server
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| H |
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| ---Sun
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| U ---FreeBSD
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| ---Windows 95
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| B |
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|___---Standalone router
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ISDN BRI line
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</verb>
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One large advantage of most routers/bridges is that they allow you to
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have 2 SEPARATE INDEPENDENT PPP connections to 2 separate sites at the
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SAME time. This is not supported on most TA's, except for
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specific(expensive) models that have two serial ports. Do not confuse
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this with channel bonding, MPP etc.
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This can be very useful feature, for example if you have an dedicated
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internet ISDN connection at your office and would like to tap into it,
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but don't want to get another ISDN line at work. A router at the office
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location can manage a dedicated B channel connection (64Kbs) to the
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internet, as well as a use the other B channel for a separate data connection.
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The second B channel can be used for dialin, dialout or dynamically
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bond(MPP etc.) with the first B channel for more bandwidth.
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<p>An Ethernet bridge will also allow you to transmit more than just
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IP traffic, you can also send IPX/SPX or whatever other protocols you
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use.</p>
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