FreeBSD's pppd and l2tpd: connection stalls

[Markus Dolze]

Hello,

I have problems with net/l2tpd. The people at their mailing list can't help me and it seems to be a problem with pppd, so I write to the list.

Situation:
I'm using L2TP over IPsec to secure a wireless lan. The lan connection itself works fine. The IPsec connection works fine (transport mode).

System:
FreeBSD 5.2-RELEASE-p2

Problem:
When I'm transfering a large file (it is *reproducable* with mozilla-source-1.6.tar.gz) transfer via ftp over the L2TP connection, the connections always stalls at the same point (number of transfered bytes). This also happens without IPSec.

I had a look with ethereal at the L2TP traffic, L2TP packets are fine, but the ppp packets insist mostly of 0x00 and ethereal reports 'bad ppp content type'. The file contains a lot of 0x00 at the position the transfer stalls. L2tpd uses pppd for the ppp connection. I tried setting MRU and MTU, but that doesn't help much (the number of transfered byte grew about 100). Disabling VJ header compression seems to have positive effect, too.

Questions:
Are there any issues known with pppd 2.3.5? 
Any ideas? 
Can anybody verify this?

Regards
Markus Dolze