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diff --git a/Documentation/isdn/syncPPP.FAQ b/Documentation/isdn/syncPPP.FAQ new file mode 100644 index 000000000..3257a4bc0 --- /dev/null +++ b/Documentation/isdn/syncPPP.FAQ @@ -0,0 +1,224 @@ +simple isdn4linux PPP FAQ .. to be continued .. not 'debugged' +------------------------------------------------------------------- + +Q01: what's pppd, ipppd, syncPPP, asyncPPP ?? +Q02: error message "this system lacks PPP support" +Q03: strange information using 'ifconfig' +Q04: MPPP?? What's that and how can I use it ... +Q05: I tried MPPP but it doesn't work +Q06: can I use asynchronous PPP encapsulation with network devices +Q07: A SunISDN machine can't connect to my i4l system +Q08: I wanna talk to several machines, which need different configs +Q09: Starting the ipppd, I get only error messages from i4l +Q10: I wanna use dynamic IP address assignment +Q11: I can't connect. How can I check where the problem is. +Q12: How can I reduce login delay? + +------------------------------------------------------------------- + +Q01: pppd, ipppd, syncPPP, asyncPPP .. what is that ? + what should I use? +A: The pppd is for asynchronous PPP .. asynchronous means + here, the framing is character based. (e.g when + using ttyI* or tty* devices) + + The ipppd handles PPP packets coming in HDLC + frames (bit based protocol) ... The PPP driver + in isdn4linux pushes all IP packets direct + to the network layer and all PPP protocol + frames to the /dev/ippp* device. + So, the ipppd is a simple external network + protocol handler. + + If you login into a remote machine using the + /dev/ttyI* devices and then enable PPP on the + remote terminal server -> use the 'old' pppd + + If your remote side immediately starts to send + frames ... you probably connect to a + syncPPP machine .. use the network device part + of isdn4linux with the 'syncppp' encapsulation + and make sure, that the ipppd is running and + connected to at least one /dev/ippp*. Check the + isdn4linux manual on how to configure a network device. + +-- + +Q02: when I start the ipppd .. I only get the + error message "this system lacks PPP support" +A: check that at least the device 'ippp0' exists. + (you can check this e.g with the program 'ifconfig') + The ipppd NEEDS this device under THIS name .. + If this device doesn't exists, use: + isdnctrl addif ippp0 + isdnctrl encap ippp0 syncppp + ... (see isdn4linux doc for more) ... +A: Maybe you have compiled the ipppd with another + kernel source tree than the kernel you currently + run ... + +-- + +Q03: when I list the netdevices with ifconfig I see, that + my ISDN interface has a HWaddr and IRQ=0 and Base + address = 0 +A: The device is a fake ethernet device .. ignore IRQ and baseaddr + You need the HWaddr only for ethernet encapsulation. + +-- + +Q04: MPPP?? What's that and how can I use it ... + +A: MPPP or MP or MPP (Warning: MP is also an + acronym for 'Multi Processor') stands for + Multi Point to Point and means bundling + of several channels to one logical stream. + To enable MPPP negotiation you must call the + ipppd with the '+mp' option. + You must also configure a slave device for + every additional channel. (see the i4l manual + for more) + To use channel bundling you must first activate + the 'master' or initial call. Now you can add + the slave channels with the command: + isdnctrl addlink <device> + e.g: + isdnctrl addlink ippp0 + This is different from other encapsulations of + isdn4linux! With syncPPP, there is no automatic + activation of slave devices. + +-- + +Q05: I tried MPPP but it doesn't work .. the ipppd + writes in the debug log something like: + .. rcvd [0][proto=0x3d] c0 00 00 00 80 fd 01 01 00 0a ... + .. sent [0][LCP ProtRej id=0x2 00 3d c0 00 00 00 80 fd 01 ... + +A: you forgot to compile MPPP/RFC1717 support into the + ISDN Subsystem. Recompile with this option enabled. + +-- + +Q06: can I use asynchronous PPP encapsulation + over the network interface of isdn4linux .. + +A: No .. that's not possible .. Use the standard + PPP package over the /dev/ttyI* devices. You + must not use the ipppd for this. + +-- + +Q07: A SunISDN machine tries to connect my i4l system, + which doesn't work. + Checking the debug log I just saw garbage like: +!![ ... fill in the line ... ]!! + +A: The Sun tries to talk asynchronous PPP ... i4l + can't understand this ... try to use the ttyI* + devices with the standard PPP/pppd package + +A: (from Alexanter Strauss: ) +!![ ... fill in mail ]!! + +-- + +Q08: I wanna talk to remote machines, which need + a different configuration. The only way + I found to do this is to kill the ipppd and + start a new one with another config to connect + to the second machine. + +A: you must bind a network interface explicitly to + an ippp device, where you can connect a (for this + interface) individually configured ipppd. + +-- + +Q09: When I start the ipppd I only get error messages + from the i4l driver .. + +A: When starting, the ipppd calls functions which may + trigger a network packet. (e.g gethostbyname()). + Without the ipppd (at this moment, it is not + fully started) we can't handle this network request. + Try to configure hostnames necessary for the ipppd + in your local /etc/hosts file or in a way, that + your system can resolve it without using an + isdn/ippp network-interface. + +-- + +Q10: I wanna use dynamic IP address assignment ... How + must I configure the network device. + +A: At least you must have a route which forwards + a packet to the ippp network-interface to trigger + the dial-on-demand. + A default route to the ippp-interface will work. + Now you must choose a dummy IP address for your + interface. + If for some reason you can't set the default + route to the ippp interface, you may take any + address of the subnet from which you expect your + dynamic IP number and set a 'network route' for + this subnet to the ippp interface. + To allow overriding of the dummy address you + must call the ipppd with the 'ipcp-accept-local' option. + +A: You must know, how the ipppd gets the addresses it wanna + configure. If you don't give any option, the ipppd + tries to negotiate the local host address! + With the option 'noipdefault' it requests an address + from the remote machine. With 'useifip' it gets the + addresses from the net interface. Or you set the address + on the option line with the <a.b.c.d:e.f.g.h> option. + Note: the IP address of the remote machine must be configured + locally or the remote machine must send it in an IPCP request. + If your side doesn't know the IP address after negotiation, it + closes the connection! + You must allow overriding of address with the 'ipcp-accept-*' + options, if you have set your own or the remote address + explicitly. + +A: Maybe you try these options .. e.g: + + /sbin/ipppd :$REMOTE noipdefault /dev/ippp0 + + where REMOTE must be the address of the remote machine (the + machine, which gives you your address) + +-- + +Q11: I can't connect. How can I check where the problem is. + +A: A good help log is the debug output from the ipppd... + Check whether you can find there: + - only a few LCP-conf-req SENT messages (less then 10) + and then a Term-REQ: + -> check whether your ISDN card is well configured + it seems, that your machine doesn't dial + (IRQ,IO,Proto, etc problems) + Configure your ISDN card to print debug messages and + check the /dev/isdnctrl output next time. There + you can see, whether there is activity on the card/line. + - there are at least a few RECV messages in the log: + -> fine: your card is dialing and your remote machine + tries to talk with you. Maybe only a missing + authentication. Check your ipppd configuration again. + - the ipppd exits for some reason: + -> not good ... check /var/adm/syslog and /var/adm/daemon. + Could be a bug in the ipppd. + +-- + +Q12: How can I reduce login delay? + +A: Log a login session ('debug' log) and check which options + your remote side rejects. Next time configure your ipppd + to not negotiate these options. Another 'side effect' is, that + this increases redundancy. (e.g your remote side is buggy and + rejects options in a wrong way). + + + |