[161] in linux-net channel archive
Re: PPP and VJ compression problem
daemon@ATHENA.MIT.EDU (Al Longyear)
Tue Mar 28 23:51:38 1995
From: longyear@netcom.com (Al Longyear)
To: scldad@sdc.com.au (Stephen Davies)
Date: Tue, 28 Mar 1995 18:58:27 -0800 (PST)
Cc: linux-ppp@vger.rutgers.edu, linux-net@vger.rutgers.edu
In-Reply-To: <199503270957.TAA00476@mustang.sdc.com.au> from "Stephen Davies" at Mar 27, 95 07:27:50 pm
Stephen Davies wrote:
> The only way I can get non-trivial transfers to work is to turn off VJ
> compression. That is:
>
> pppd /dev/cua1 38400 -vj asyncmap 00000000 crtscts lock defaultroute connect
> 'chat -v -f /etc/pppscript'
>
> works perfectly but if I remove the -vj, I get disconected after
> transferring
> a couple of K bytes.
How about after a couple of frames for a connection? Say, 16 . . . :)
> Mar 27 18:12:52 mustang chat[233]: Cisco Systems - Customer
> Information
> Mar 27 18:13:17 mustang pppd[232]: sent [IPCP ConfReq id=0x1 <addr 203.2.199.1>
> <compress VJ 0f 01>]
> Mar 27 18:13:17 mustang pppd[232]: rcvd [IPCP ConfReq id=0x1 <compress VJ 0f
> 00> <addr 192.189.54.157>]>
Here is the request from the remote asking if it is legal to use VJ
header compression with 16 slots.
> Mar 27 18:13:17 mustang pppd[232]: sent [IPCP ConfAck id=0x1 <compress VJ 0f
> 00> <addr 192.189.54.157>]
The answer from Linux is yes.
> Mar 27 18:13:17 mustang pppd[232]: rcvd [IPCP ConfAck id=0x1 <addr 203.2.199.1>
> <compress VJ 0f 01>]
Here is the acknowledgement that the system will accept 16 slots.
Stephen,
There are some terminal servers which will do nasty things such as
'lie'. They will say that they will accept VJ header compression with
16 slots as indicated by the trace above. Unfortunately, they really
don't expect clients to use that many slots.
You should try the option "vj-max-slots 1" and see if this will work
rather than disabling the VJ header compression all together. If this
does work, try it with two, then three. You may have to work up to 16,
which is the default value.
Possible problems have been noted for the Annex (Xylogics) terminal
server with their 5.2 revision code.
In addition, the 'dp' program with revision 3.1.2 had problems for
other reasons, but along the same lines.
--
Al Longyear longyear@netcom.com
