Subject: (usr-tc) strange MPIP problem

From: Mark Thornton <[email-masked]>
Date: Wed, 16 Feb 2000 16:43:13 +0000

I ran into a strange MPIP problem and wanted to see if anyone else has
experienced this.

Yesterday I decided to move the mpip server from my primarily ISDN chassis
to one of my dialup chassis with less traffic. The modem MPIP clients were
fine, but ISDN clients using the NetGear router began having trouble
authenticating. A PPP monitor of the connection showed that it stalled for
10-15 seconds after receiving the username/password packet, then requested a
disconnect. Other ISDN clients were working just fine. The problem continued
through the night as more clients using the NetGear called to complain. I
went back and reversed out the only change I had made in the dialup system
and they were immediately able to log in.

What impact could MPIP have during the login process? It was the initial
channel that was failing, not the bundle.

Mark Thornton
San Marcos Internet, Inc.
512-393-5300

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From: Jeff Mcadams <[email-masked]>
Date: Wed, 16 Feb 2000 16:53:24 +0000

Thus spake Mark Thornton

>Yesterday I decided to move the mpip server from my primarily ISDN
>chassis to one of my dialup chassis with less traffic. The modem MPIP
>clients were fine, but ISDN clients using the NetGear router began
>having trouble authenticating. A PPP monitor of the connection showed
>that it stalled for 10-15 seconds after receiving the username/password
>packet, then requested a disconnect. Other ISDN clients were working
>just fine. The problem continued through the night as more clients
>using the NetGear called to complain. I went back and reversed out the
>only change I had made in the dialup system and they were immediately
>able to log in.

Who requested the disconnect?  Or did it just drop?  I sounds, perhaps,
like the system is trying to contact the MPIP server but is unable to do
so...after 10-15 seconds, I would expect one side or the other to
request a disconnect thinking something isn't working right.  I'm not
sure why this would specifically affect Netgear's, and not other
multi-link dialin's that would be hitting the same chassis, but that
sounds like its what's going on.

Check to make sure your server has all the clients configured in it with
all the right shared secrets and stuff.  There's just not that much to
configuring MPIP to make it work.

Oh, I also am assuming that you're using Arc's for all your service with
MPIP...MPIP was always broken on NETServers...save yourself a lot of
time and frustration and don't even try to do MPIP on NETServers.  :)

>What impact could MPIP have during the login process? It was the
>initial channel that was failing, not the bundle.

The systems use MPIP after they get endpoint discriminator and
authentication information (endpoint discriminator, EDO, information is
exchanged during LCP, authentication is the usual PAP, CHAP, whatever).
Multi-Link uses a combination of endpoint class, endpoint discriminator,
and authentication name to determine if the new dialed in link belongs
to an already existing bundle or not.  If all three of those values
match an already existing bundle, then the link is bundled in with that
bundle...if any don't match, a new bundle is created.  So, the systems
transmit this information via MPIP to the MPIP server to find out if
there is an already existing bundle with those three values.  If the
system can't contact the MPIP server, I assume something would
eventually timeout and a disconnect would occur.
-- 
Jeff McAdams                            Email: [email-masked]
Head Network Administrator              Voice: (502) 966-3848
IgLou Internet Services                        (800) 436-4456

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