Got a shark fin modem, manual:
[link|ftp://ftp.3com.com/pub/cable_modems/3cr29220/tailfin_2369_00.pdf|ftp://ftp.3com.com/p...ilfin_2369_00.pdf]

It has been failing in such a way that it refuses to see
the name server across the way.

Ping tells me:
"From 149.112.50.65 icmp_seq=46711 Destination Host Unreachable"

The modem's internal address is 149.112.50.65. All of them are.

Sometimes the shark would make some noise, lose it's WAN
address, and pick up a totally bogus one, making the whole
world unreachable. 3 minutes later, it would pick up the right one.

It was CONSTANT last Thursday. Friday they came, worked on
the wires, said all signal levels are low, they'd be back.


It then worked, off and on. DL 20-30MB OK, then pause for a while,
etc, etc. Would kill my office VPN sessions forcing me
to log back in, re-ssh, etc.

They came back today, saw them working on the pole.

Same symptoms.

ARRGG!!!

I call. They had closed out the trouble ticket.

BASTARDS!

They reopened the ticket and will be here tomorrow. I
lost it on the phone support person, which is RARE. I power
cycled the modem for her (I was feeling generous), but
then she gave the standard spiel about how rebooting the
computer usually helps. I explained that it was hooked to
a home network via a Linksys router. She said, "Oh, that's
why I can't ping you". She started on the difficulty of
diagnosing non Windows environments.

I then exploded.

YOUR PEOPLE DETERMINED YOU HAVE LOW SIGNAL STRENGTH.
THEY WERE HERE LAST WEEK, THEY WERE HERE TODAY, SO OBVIOUSLY
THEY THINK IT IS A PROBLEM WITH THE WIRING OR YOUR SYSTEM
AND NOT MY PARTICULAR SETUP. BUT I HAVE A DEDICATED WINDOWS
PC SETUP THAT I CAN PLUG THIS INTO DIRECTLY IF YOU INSIST,
EVEN THOUGH WE KNOW IT WILL MAKE NO DIFFERENCE AT ALL!!!!!!!

That's when she put me on hold, came back, and promised a
guy out the next day. Good thing I was planning on working
home all week. Too back it's tough to work at home
via Putty over dialup when I can't trust the cable.

I did a bit of research on this model and signal strengths.
According to web lore (does NOT match the docs at all, but
neither do my current singal strengths)

> You can check the levels your self with the IP address 149.112.50.65.
> Levels in should be less than 7db and greater than -5.
> REturn should be less than 45db. Any higher and it may affect
> the speeds. Noise can also cause problems and is introduced

My current setting are:

Downstream Receive Power Level: -12 dB
Upstream Transmit Power Level: 47 dB

This means I am out of spec according to the guy who wrote that,
but the docs show numbers wildly different. I assume this guy
is closer than the docs and the docs refer to a different release.

I have difficulty forcing the problem to appear. I placed
a 24MB file on my Comcast web space (max 25 MB) and toss off
a bunch of "curl >/dev/null" processes. Sometime they hang
but they very rarely show the ping failure.


So, where is the authoritative source on all things cable
modem? Or do I start looking at DSL, which is more expensive
AND slower, at least here?

They seemed to have done somthing at about 11PM last night.

Now:
Downstream Receive Power Level: -11 dB

Before
Downstream Receive Power Level: -12 dB

7dB - -5dB is the "range", so it got a bit better.

My failure rate has dropped and my office VPN has not died.

My firmware is too old to take advanatage of the diags they point out on that page.
Oh well.

for now.

Swapped out the tailfin modem for a Motorola SB5100.

Sucker run 3 times faster than the tailfin!!!!!!
Calculated based on true file sizes being moved,
not random spec.

I've been running many simultaneous DLs of my trash
file to >/dev/null, while working in multiple SSH sessions,
while having a Cisco VPN up.

Not a burp.

Typical name server ping times are are 9ms. When I am pulling 364KB
per second down my name server ping times go to 12-29ms.

Many DLs, no failures.

Ssh bash command line feels local.
A remote vim session over ssh barely feels it.

I LOVE THIS THING!!!!!

1) Do you have a business account?

Far more leverage.

My brother Rob has a problem with his local cable company. He had a business account that he paid 3K for over a 6 month period. When the techies were working on his line started making noises about leaving at 5PM he raised hell. They worked all weekend, replacing almost every piece of equipment between him and the headend.

The service manager called him and bitched about him demanding people work all weekend and the costs involved. Rob responded: Gimme your boss. He then raised hell concerning the intermittant problems and outlined how much money he lost (or claimed to have lost) due to the crappy service. They wrote him a check for $2,200.

2) Keep the executive level letter under 1 page. You can have up to 4 pages of supporting detail, but do NOT overhwhelm them.

3) The master cover letter should include a list of everyone else who is receiving. Let them know who is involved. Let them shake in terror. Let them start scrambling to cover their asses. The initial reaction will give the other guys ammo, or it may lead to solving your problem.

4) Follow up with phone calls. Try to get reactions. Call each person who is not in the direct line of fire and ask their opinion and if they recommened you speak to someone else. Be happy to be their weapon in their quest for corporate domination. It may help you later as a contact.

5) Keep a really good log of every conversation. As you move through the list, drop an occasional name of the other people you were talking to. This willl give an appearance of connectedness and people will be more likely to talk to you in order to further their own careers.

6) Be cordial. Do not insult any of the techs. When speaking to the execs, stress that you understand getting reliable tech people will always be a problem, and you will be happy to work toward a resolution with whoever they direct you to. For all you know, you will get a high level job out of this.

7) Don't claim to be a technical person who can solve their problems. You don't TRULY know their internal systems so what should be a simple fix to you could be horribly complex. Even if you are right, it will not matter since you have no internal standing. Simply state you have faith their ability to solve the issue and keep pushing.

Back to dialup.
Can find a downstream signal blinky light.
ARRRGGGGG!!!!

They will be back on Wednesday.