[rbak-nsp] Strange auth problem after enabling mlppp

[Ian Calderbank]

Yeah, I started working with sms1000's in '00. Nice when the old stuff is
still going.

It'll be the logging config - "logging syslog debug " or something like
that.

Yes, there are various issues...

Timing -  Those T1's are near perfectly synchronous, to the microsecond
(unless the carrier has some serious issues). ADSL's are not, multiple 10's
of milliseconds jitter between any given pair is not uncommon, run a
per-packet load-balancer over that and tcp is screwed by out of order
delivery. The MLPPP support in the SMS , from memory was targeted at
synchronous circuits - ISDN and DS1/T1. 
Thoughput - Those T1's are also exactly the same speed - to the bit. Again,
any two ADSL's are not exactly the same throughput (no matter what the sync
may say). If they are significantly different, there's no way to bias it
towards the faster one.

You've got zero support from RB/ Ericson on this (SMS500 went End Of Support
a number of years ago) so it would be a real suck it and see approach.

There are boxes that do ip layer load balancing of course, the trick is to
find one that is designed to work in a way to bond multiple DSL lines
together, I happen to be doing some work for such a one at the mo, so I'll
PM you the details to avoid too much OT on this list.

ta
Ian

 -----Original Message-----
From: Andy Dills [mailto:andy at xecu.net] 
Sent: 27 July 2010 19:12
To: Ian Calderbank
Cc: redback-nsp at puck.nether.net
Subject: Re: [rbak-nsp] Strange auth problem after enabling mlppp

On Tue, 27 Jul 2010, Ian Calderbank wrote:

> Hey, an SMS500. Nice to see some history still going. J

It was purchased used in like 2003, when Verizon finally rolled out DSL in
our LATA, and hasn't so much as blinked since. We picked up another used one
just in case this one ever died.

> Debug ppp and/or aaa on your sms, can't remember the sub-options but 
> you want the one that shows you the contents of the LCP messages.

That makes sense...

I just turned on "debug ppp lcp".

However, I'm having a hard time getting the debug messages sent via syslog.
It's not the end of the world to get them from the unit directly (they show
up in "show log"), but it's odd to me that the debug logs aren't being sent
with the rest of the info being sent via syslog. If anybody has any thoughts
on that I'm all ears.

I'll test again tonight and see what I see on the redback end.

> Its probably the two ends disagreeing about lcp options, with the 
> obvious suspect being multilink. It may be that your modem doesn't 
> like being offered it, and one end or the other is refusing to negotiate
it away.
> Without debug info, its hard to know which.

That makes sense. 

> MLPPP Bonding is notoriously hard to get working on dsl, good luck. I 
> have some alternative technology suggestions to achieve that end if 
> you want, PM me.

Would you mind explaining why it's hard to get working? That seems strange
to me, given that it works just fine when doing things like bonding 6 DS1s.
Is it the asynchronicity? 

I haven't found much about mlppp DSL when searching. We're planning on using
a cisco 1700 with 2 DSL WICs on the CPE side.

Initially, this is to supply me and one of the other partners with a beefier
connection at home, so we're pretty motivated to find a way to make it
happen, even up to purchasing a newer AOS (is that even possible?) or
equipment.

Thanks,
Andy

---
Andy Dills
Xecunet, Inc.
www.xecu.net
301-682-9972
---