bluetooth channels -- not very clear on concept

[Zhang Weiwu]

Maksim Yevmenkin wrote:
>
>Hello,
>
>[...]
>
> > On my configuration I setup LAN access server listen to channel 1, and
> > everyone dials in on that channel. I'm not sure of the concept of
> > "channels",
>
>  *:1 - LISTEN -- main server
>  BD_ADDR_LOCAL:1 <-> BD_ADDR_REMOTE1:1 -- client (1)
>  BD_ADDR_LOCAL:1 <-> BD_ADDR_REMOTE2:1 -- client (2)
>
>becase BD_ADDR of the remote device is different you can share the same
>RFCOMM channel between serval devices.

Nice. Now I got it. Thank you.

>
> > sometimes when other people are connected, I use "rfcomm_pppd
> > -c -C LAN -l bluetooth-client" and get "no socket available" prompt, 
then I
> > use "rfcomm_pppd -c -C 1 -l bluetooth-client" and it works.
>
>hmmm... is that the exact command you using? in client mode (-c) you need
>to specify the address of the server to connect to (-a) otherwise it will
>not work. also what does "no socket available" is that the error you are
>getting?

Sorry I wasn't clear. Here is the script(1) to produce the problem:

thinkpad# rfcomm_pppd -c -a 00:04:61:80:6f:e4 -C LAN -l bluetooth
rfcomm_pppd: Could not obtain RFCOMM channel: Socket is not connected
thinkpad# rfcomm_pppd -c -a 00:04:61:80:6f:e4 -C 1 -l bluetooth
thinkpad# ifconfig tun0
tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 1500
        inet 192.168.0.87 --> 192.168.0.120 netmask 0xffffffff
        Opened by PID 47776

MAC OS and Windows doesn't ask for Channel number. They recognize LAN and 
connect to channel 1. Linux user always gets refused. (so strange the Linux 
bluetooth LAN tool pand(1) don't have a parameter to specify what channel 
to connect to.)

> > Sometimes (not very frequently) iBook disconnects and cannot connect
> > anymore unless the
> > bluetooth ppp server restart. (Windows notebook no problem.) Is it 
because
>
>that is strange. i'd like to take a look at hcidump output. you will need
>to download it from http://www.geocities.com/m_evmenkin/

Do you mean your homepage? You forgot I am in China I cannot go to 
geocities. To help me you sent me your sdp package through email a week 
ago:)

Today the iBook problem is (I guess) solved. I found this line in ppp.log:
Mar  3 10:59:34 dino ppp[2274]: Phase: deflink: ** Too many ECHO LQR 
packets lost **
I disabled lqr, the iBook don't have the problem any more.

> > we are sharing channel No.1? Should I register LAN service on channel 
one
> > through channel six?
>
>if you only have one bluetooth device attached to the server then you
>should be fine. you need to register mulitple RFCOMM channels only if you
>are running multiple RFCOMM servers. you can do it if you have more the
>one bluetooth device attached to the server. again, keep in mind that a
>single bluetooth device can only have 8 clients at a time.

Thank you for the advice.

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