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[Weaver]

Packet loss in PPP LCP pings continues just the same, bright red ‘dripping blood’ from the top of the graph down.

[Weaver]

I've now swapped lines @a.4 and @a.1 at the wallsocket points. The fault has now moved to graph 4 in clueless. Sanity check: So this means a bad modem in line 1 doesn't it? (Brain failing due to exhaustion, apol.)

Status now: Graph 1 currently clear, graph 4 dripping blood.

Suggestion: Earlier perplexing results would just mean that it's either something to do with duff PSUs - which have not been swapped out (thanks Burakkucat, for pointing this out) - or there's more than one bad modem in the spares pool?

[d2d4j]

Hi weaver

Why not save time and change the power supply from a known good router with the perceived bad router

If issue is then seen on the good router as was with original power supply, you know it's the psu

If the issue stays with the perceived bad router, just change the router with good to see if it resolved issue (keep it on same line though)

If issue remains, can you factory default bad router and reset it back up, then test

Your theory over bad router spare seems ok, but I would test this by changing a good router with this spare and see if issue arises

Many thanks

John

[Weaver]

@d2d4j good point. Will do, delayed because I  have been waiting a short while to let A&A collect a little more data.

[Weaver]

FYI: I must not put these devices back to factory settings as they need to be in modem-only mode (bridge mode) which is a non-default setting preconfigured by AA before delivery.

(Btw And as routers they are shite, a security hazard, and in any case unusable as what I need is a straight PPPoE modem not a router. See earlier thread investigating the innards of the DLink DSL-320B-Z1:
   http://forum.kitz.co.uk/index.php/topic,17065.msg313922.html#msg31392
)

[Weaver]

This afternoon, I changed the modem out yet again, for yet another spare. (I have a lot of fairly new spares.) I also swapped out the PSU along with it.

I then swapped the lines back at the Wallsockets to the way they were originally.

[burakkucat]

As long as you are keeping notes of each experiment performed and the result obtained, then you should be able to rule out (or in) any particular item of local hardware.

I have to confess that now I am completely ker-fuddled as to "what's what". 

[Weaver]

The next step was to question the Firebrick itself, as its port operations haven't been investigated. I swapped the Ethernet cables between modems #1 and #3 (line @a.4) where they go into the Firebrick's ports.

Amazingly this has almost 99% cured the problem, with a microscopic amount of dripping blood just before every hour. This time pattern suggests a software bug perhaps.

I looked back at the Firebrick software upgrade status, and I noted that there had been a software upgrade a few days before the onset of the fault, but there's no obvious way to explain with the time gap between the installation and the start of the fault.

One other thing I should look at is the network cables between Firebrick and modems just in case they could have been damaged.

So the current state is that the dripping blood is spectacularly reduced, down to acceptable levels. Because the cables are into the wrong ports compared with the line identifiers @a.1, @a.3 etc, I will have to clean up somehow.

At the moment, the Firebrick config is wrong, because it specifies an upstream traffic limit in bps for each line, and these have got scrambled. Line 1 has traditionally had a rather higher upstream traffic allowance than the others, this is now incorrectly assigned to line @a.4 and vice versa. I wonder if this upstream rate limiting system could have something to do with it. It would have to have been hacked in the most recent release.

[Weaver]

All of this work carried out by my beautiful assistant, thanks Janet.

[Chrysalis]

This is very hard to guess remotely what might be going on, cable swapping improving things would suggest to me tho that the line isnt at fault.

Swapping the cables on the firebrick would also perhaps serve to re-initiate the connections, flushing buffers and so forth, meaning it could be something like a memory leak which got resolved when the port was reset. So another idea is if it starts getting worse, dont swap any cables but just reboot the firebrick, to see if that also yields a temporary improvement.

[aesmith]

I think the A&A monitoring is by LCP ping, so I was wondering whether that would preempt any traffic shaping on your PPPoE router.   Depends how the shaping an queuing is done on  the firebrick.   Does the A&A graph show packet loss if you max out your links with real traffic?

[Weaver]

No, it doesn't seem to show bright red in the period of a speed test.

[Weaver]

And it's back. Bad as ever, after about 22 hrs. It came back showing on line @a.4 at around 15:30. This line is the one that originally was connected to port #3 of the Firebrick, now it's connected to port #1 on the FB.

So it seems (sanity check pls?) that the trouble follows Firebrick port #1 around.

[burakkucat]

So it seems (sanity check pls?) that the trouble follows Firebrick port #1 around.

For the first 24 hour period, connect the equipment as --

• Line 1 > Port 1
• Line 2 > Port 2
• Line 3 > Port 3

For the second 24 hour period, connect the equipment as --

• Line 1 > Port 2
• Line 2 > Port 3
• Line 3 > Port 1

Then, finally, for the third 24 hour period, connect the equipment as --

• Line 1 > Port 3
• Line 2 > Port 1
• Line 3 > Port 2

For each of the three 24 hour periods note which line shows the problem. If it is Line 1, Line 3 and Line 2 then that does appear to point to Port 1 on the Firebrick.

Perhaps you should suggest to Adrian Kennard that he might like to spend a long weekend at Skye Shepherd Huts and, whilst in the vicinity, take a look at your Firebrick FB2500?

[Weaver]

> Perhaps you should suggest to Adrian Kennard that he might like to spend a long weekend at Skye Shepherd Huts and, whilst in the vicinity, take a look at your Firebrick FB2500?

That's an excellent idea. I'm told it's very agreeable there!