10-18-2010 01:49 AM - edited 03-03-2019 06:05 AM
Hi!
We use a Cisco 2811 with an PRI ISDN card to provide dial-out modems.
What we want to do now:
We try to use the reverse telnet feature to dial out with pppd from Linux. Dialing out and connecting our third party works fine BUT: when the PPP-session is disconnected the Cisco router still shows the modem as in use. And after 30 dial out attempts the router tells us: No more modems
How can I release this modems?
This looks like this when I issue the who command:
C2811-FABL-T#who
Line User Host(s) Idle Location
tty 0/322 Async interface 00:00:00
tty 0/323 Async interface 00:00:03
tty 0/324 Async interface 00:00:07
tty 0/325 Async interface 00:00:06
tty 0/326 Async interface 00:00:00
tty 0/327 Async interface 00:00:01
tty 0/328 Async interface 00:00:01
tty 0/329 Async interface 00:00:08
tty 0/330 Async interface 00:00:01
tty 0/331 Async interface 00:00:01
tty 0/332 Async interface 00:00:10
tty 0/333 Async interface 00:00:01
tty 0/334 Async interface 00:00:03
tty 0/335 Async interface 00:00:10
tty 0/336 Async interface 00:00:07
tty 0/337 Async interface 00:00:01
tty 0/338 Async interface 00:00:10
tty 0/339 Async interface 00:00:09
tty 0/340 Async interface 00:00:01
tty 0/341 Async interface 00:00:01
tty 0/342 Async interface 00:00:03
*514 vty 0 tsea idle 00:00:00 10.113.1.65
Interface User Mode Idle Peer Address
The config we use:
line 0/322 0/357
modem DTR-active
rotary 1
no exec
transport preferred telnet
transport input all
The command to connect with ppp looks like this:
/usr/sbin/pppd debug linkname 3xocL9f7HO connect "/usr/sbin/chat -T <telnr> -f connect.chat -v" disconnect "/usr/sbin/chat -f disconnect.chat -v" pty "/usr/bin/nc <router IP> 5001" user <username> password <password> 172.28.0.2:172.28.1.2
connect.chat:
ABORT BUSY
ABORT ERROR
ABORT 'NO CARRIER'
ABORT 'No Modems Available'
TIMEOUT 10
name: <Router username>
TIMEOUT 5
word: <Router password>
'' ATZ
TIMEOUT 5
OK ATDT\T
TIMEOUT 60
CONNECT \c
disconnect.chat:
'' +++\d\dATH
TIMEOUT 5
OK ATZ
TIMEOUT 5
OK ^U
Sorry if I miss some important information here. I am no Cisco admin.
CU
Thomas
10-25-2010 10:45 AM
Either the Linux device needs to cleanly disconnect the TCP session or you need to set up modem control on the lines so that a disconnect on the modem forces down the TCP connection.
What you want is
line 0/322 0/357
modem inout
Provided that the modem will drop DCD between calls (the default setting for most modems) this will ensure that the TCP session is dropped.
This section will be useful to understand the different modem control configurations
"debug modem" is also helfpul to monitor line states.
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