[c-nsp] Strange DS3 Problems

[Jay Hennigan]

Adam Piasecki wrote:

> I'm currently having two problems with the Ds3,
> 
> 1) The max download speed i've ever gotten is 700kb/s, this doesn't seem
> right at all for 10/10mb dedicated, 45mb burstable.

Definitely not right.

> 2) the Ds3 is bouncing. It goes into a down/down state and i'll have a FERF
> alarm light on the router. This will clear in about 20-30secs without me
> doing anything.

FERF = Far end receive failure.  The other side is reporting loss of 
signal from you.  Other end should be seeing a boatload of input errors 
and carrier transitions in this condition.  Transmission to you from ISP 
is fine.  Transmission from you to ISP is impaired.

> It seems to happen more when the Ds3 is under load, though it has happend
> without any load.

How is the circuit clocked?  Ensure that there is exactly one clock 
source on the circuit and that framing and linecode match throughout 
among you, your ISP and carrier.  (Usually C-bit B3ZS, clock source from 
ISP.)

> Questions
> 
> 1) What is the rx FEBE since last clear counter mean? I notice this is the
> only sort of error i'm getting now.

Far end bit errors.  The remote end is signaling to you that it is 
receiving errors from you.  An attenuator on the other side may be 
needed, and/or the other end may have bad cabling or faulty equipment 
receiving from you.  The other end is likely seeing input errors 
corresponding to your FEBEs.  This correlates to the FERF alarm, 
pointing to a problem in the direction leaving you and arriving at the 
other end.

> 2) Is a 7206 non-VXR NPE 200 strong enough for a full DS3, if i'm just doing
> a default route, and a very small ACL.

Yes, without breaking a sweat.

> 3) Is it possible that i have a BAD PA-T3, I did have it connected without
> the Attunator for sometime,
> and i'm afraid that might have fried something.

If so it would be on your transmit side based on the FEBEs.  Can you run 
clean to a remote co-ax loop at the ISP?  Can the ISP run clean to a 
co-ax loop on your side?

> 4) Has anyone used Fiber to DS3 converters in the past? Good/Bad?

No direct experience but be sure to include their configuration options 
when verifying clocking, linecode, framing agreement.  Verify light 
levels and clean optics.  If dark fiber end-to-end with no intervening 
repeaters, swap transmit and receive strands on both sides and see if 
the direction of impairment flips.  If so, this would indicate a problem 
with the fiber media.

You'll need someone with clue on the other end of the circuit to help 
you troubleshoot this, as the problem is coming in to their end.

--
Jay Hennigan - CCIE #7880 - Network Engineering - jay at impulse.net
Impulse Internet Service  -  http://www.impulse.net/
Your local telephone and internet company - 805 884-6323 - WB6RDV