[AusNOG] DSLAM Dropout issues

[Stavros Patiniotis]

Hello,

For simplicity I'll answer all the questions here in one reply.

The dslams, which are used in private building setups, where purchased from
Versatek. The model is the 24 port adsl2+ vx1000mdi -
http://www.versatek.com./products/vx1000md.htm.

Originally the BRAS were Mikrotik RB450G, but not being familiar with these
devices, I recently installed a Cisco 1841. Before we took over the services
where in bridged mode, but we've made an effort of the last couple months to
swap to pppoe. This is when we've noticed the problem as radius reports
between Lost-Carrier & User-Request disconnects etc. The dslam functionality
is very basic and so there is no way to tell if a port is losing sync,
unless you are polling a web interface every 30 seconds (which I haven't
done).  

I have tried a couple different firmware versions (as supplied by versatek),
as a result of this issue, with no improvement.

A trace of PPP on the bras and modem shows that the modem's are requesting
the disconnect, even though all keepalives are being received and modems in
nailed up mode etc. http://pastebin.com/PK3MjQgy 

We have customers using a variety of modems eg Netgear, TPlink, VER170P and
Netcomm NB5, NB6 etc. The PPP drops happens on the nb6plu4w but not the nb6.
Running a windows 7 pppoe session through the nb6plus4w (ie as a simple
bridge) will solve the problem.

Stavros