[AusNOG] DSLAM Dropout issues

[Andrew Cox]

Hi Stavros,

For this disconnection you've included it looks as thou the line has dropped
then the pppoe (so a sync issue would be the cause).

*Mar 18 23:04:13 (none) daemon.crit syslog: Clear IP addresses.  Connection
DOWN.*
*Mar 18 23:04:13 (none) daemon.crit syslog: Clear IP addresses.  PPP
connection DOWN.*

However where you're seeing a seperate PPPoE disconnect but without the sync
drop read on:

Pastebin it looks like that was taken directly from one of the RB450G's,
there's a number of things to look at here to determine what might be a
possible cause, including the default ppp profile setups on the RB450G's

Are you able to include the output of */ppp profile export *excluding any
profiles you're not using?

Just guessing based on what you've said so far but it could be incorrectly
set keep-alive or session timeout on the RB450G

If a modem isn't responding to the keep-alive requests then it'll be
disconnected, turning this off will stop sessions from disconnecting unless
initiated by a user-disconnect or the BRAS is rebooted (or manually via
winbox/ssh etc). If you're just trying to determine the cause, I'd try
setting this to 0 and ensure the one-session-per-host value on the ppp
profile is active.

Have a super mega nice day.

Kind Regards,
Andrew Cox, MTCNA
AccessPlus - Head Network Administrator
BigAir Universe Broadband - Senior Network Administrator
Ph: 1300 739 822 (7am - 12 midnight AEST)

On 29 April 2011 01:42, Stavros Patiniotis <stavros at staff.esc.net.au> wrote:

> 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
>
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