LCP down!

Hey... what exactly does it mean in the router logs when it says "LCP down"? I occasionally get disconnections which are picked up by the router log, and they always say "LCP down" followed by the LCP coming up again, and then CHAP authentication success.

But sometimes (see examples below), the connection comes back within a few seconds. Sometimes it takes a few minutes. I'm on AOL and sometimes I know it's affected other AOL users, and they've got the same thing in their logs.

So when an LCP down error occurs, is it always an AOL issue? I've seen router logs sometimes show "Loss of synchronization" which I think is the line losing synch with the exchange. I don't normally get that though, so I assume these LCP errors aren't between me and the exchange... or am I wrong?!

Fri, 2009-09-04 00:01:56 - LCP down.
Fri, 2009-09-04 00:01:57 - Initialize LCP.
Fri, 2009-09-04 00:01:57 - LCP is allowed to come up.
Fri, 2009-09-04 00:02:02 - CHAP authentication success

Fri, 2009-08-28 00:38:05 - LCP down.
Fri, 2009-08-28 00:38:05 - Initialize LCP.
Fri, 2009-08-28 00:38:05 - LCP is allowed to come up.
Fri, 2009-08-28 00:39:06 - Initialize LCP.
Fri, 2009-08-28 00:39:06 - LCP is allowed to come up.
Fri, 2009-08-28 00:39:55 - CHAP authentication success
Fri, 2009-08-28 00:40:26 - LCP down.
Fri, 2009-08-28 00:40:27 - Initialize LCP.
Fri, 2009-08-28 00:40:27 - LCP is allowed to come up.
Fri, 2009-08-28 00:40:44 - CHAP authentication success

By the way, I should add that I live VERY close to the exchange and my line stats are very good as a result... so I'm not convinced that the occasional disconnection is anything local....

LCP is the Link Control Protocol, used by PPP to separate out the housekeeping traffic it needs to know about from the actual traffic that you/'re interested in.

I noticed in my logs that I had another brief disconnection for a few seconds last night (see below).

Wed, 2009-10-28 02:15:32 - LCP down.
Wed, 2009-10-28 02:15:32 - Initialize LCP.
Wed, 2009-10-28 02:15:32 - LCP is allowed to come up.
Wed, 2009-10-28 02:15:43 - CHAP authentication success

I was just intrigued; is this a loss of connection between the exchange and the ISP? Or is it between me and the exchange? If it was between me and the exchange, wouldn't there be a "loss of synchronisation" message too?

I can vouch that its not restricted to AOL - my Virgin ADSL shows it (usually in bursts) too.

Is this from a Linksys router by any chance?

I used to see the same report in my router logs from a Linksys WAG200G. It's the router losing sync with the exchange. Might be worth your time posting your router stats for us.

In my case, I was losing sync due to bursts of noise on the line, which hs ended up in a repair to my incoming cable and a lift-and-shift at the exchange.

No it's from a Netgear DG834v3. I don't think it is necessarily losing synch with the exchange when it does it, because it also reports "LCP down" when I know there's a problem with AOL (i.e. it's affecting other users too).

I think the router reports "Loss of synchronisation" if you lose synch with the exchange, and I didn't get that. For the record, my downstream line att. is 14db, and my downstream SNR margin is about 13db, so no problems there at all.

It doesn't do it often, but I was just curious as to what it means. I've seen it do it once or twice where it does something like this:

03:27:01 CHAP authentication success
03:27:01 LCP down
03:27:01 Initialize LCP
03;27:01 LCP is allowed to come up
03:27:05 CHAP authentication success

On that example, there was nothing in the log before the first "CHAP authentication success"! It seems somehow that perhaps AOL did something with their CHAP servers and it upset my connection (on that occasion, anyway).

Are you syncing at 8128kbps down? That SNR margin looks a little high, unless you're syncing at full speed with room to spare. Best thing to do is post your router stats.

I'm confident it's not a line fault as this doesn't happen that often - maybe once every 2 weeks. And like I said, normally when it does happen, I find other people are complaining that theirs went off too. I was just wondering exactly what "LCP down" meant, as it seems the router uses that phrase to indicate the connection has gone down, regardless of what caused it.

(Also, it once happened when I was using the internet so I was able to immediately check the router - and it was still synched to the exchange despite the log saying "LCP down". So I don't think too much can be read into that phrase, unfortunately.)

Here are my stats anyway...

ADSL Link Downstream Upstream
Connection Speed 8128 kbps 448 kbps
Line Attenuation 14 db 3 db
Noise Margin 13 db 26 db

Edited by deleted (Fri 30-Oct-09 10:46:32)

LCP Down means the router has lost connectivity with the ISP although the router is still seeing the actual ADSL line. With a Netgear which has an LED for ADSL and one for Internet, you should find the ADSL LED is still on but the Internet LED is off.

John.