"blocked" Line Status?

[Guest Buzby]

Hi there,

 

We're using VG 6.0.3377 and are getting a 'Blocked' line status on one of our servers. It doesn't affect calls, but it frequently 'overwrites' the current status of each call in the Line Monitor application which is very annoying.

 

I've attached a hardware log example in the hope you can shed some light on the status, I can see errors in the logs which I suspect is related.

 

If we need to speak to our ISDN provider - specifically what technical information should we give them - at the moment they are saying that 'Blocked' is not a status provided on their lines so they're having nothing to do with it.

 

Cheers,

Tyron

0816tw.zip

[SupportTeam]

'Blocked' is whenever a channel is taken out of service. Most ISDN switches can 'block' individual channels, and dropping the ISDN D channel will 'block' all of the channels on the trunk.

 

Trace shows that Dialogic is reporting DTE1_ECS - Error count saturation errors. (frame error, CRC error, synchronization problem etc.)

 

Often it caused by incorrect clocking setting; for example, when both provider and the board try to create a clock. In your case the board, most likely, must derive the clock from the network; you may want to double-check with your provider.

 

Ensure Clock Source in Dialogic Config Manager is set to Network. Also check your wiring.

 

Which Dialogic card and drivers are used on this system?

[Guest Buzby]

Thanks for replying, we're using a Dialogic D/600JCT-2E1 card with SR 5.1.1, with SP1 and point release applied.

 

I cannot find the 'Clock Source' option in the DCM for this card - not sure where I should look?

 

It's wierd - the system never used to do this - it has been installed for over 3 years but only done this for the past 6 months or so. Maybe you're right about the wiring, but surely damaged wiring would makes the calls unreliable (which they're not)?

 

Could the errors derive from other factors beyond our control, such as noise on the line or similar?

 

Cheers,

Tyron

[SupportTeam]

In SR6.0 go do a 'Configure Device' on the card and on "TDM Bus Configuration" tab select:

Derive Clock From : NETREF_1

 

Provide NETREF One From : NetworkInterfaceOne

 

Guess electrical noise can affect connection as well. Check that cabling is well away from other electrical equipment.

 

(BTW. With 600JCT we recommend using SR6.0 and VG v7)

[Guest Buzby]

Thanks - just checked that screen and both parameters are already set. In fact, they're not changeable either even with the service shut down.

 

There's a custom cable going between the ISDN NTU and our Dialogic card, so we can't replace it, but it doesn't overlay any electric cables etc. I'll check to see if the electrical supply to the NTU is smoothed.

 

I guess there's not much more we can look at other than speaking to the telco again?

 

Cheers,

Tyron

[SupportTeam]

Best to speak to both Telco and to card supplier.

 

You may need to run ISDIAG on the card and monitor for errors and/or have Telco attach a protocol analyser to your E1 trunk at your premises.

[Guest Buzby]

Hi there,

 

Just a short note to let you know that the problem has now been resolved. We spoke to the telco who came in and measured a 'high resistance' on the copper cable linking the main fibre in the street to the NTU next to our server. They replaced the few metres copper and the blocked status disappeared.

 

Apparently most ISDN switches wouldn't have noticed this fault, only Dialogic cards are sensitive to faults like this.

 

Thanks again for your help.

 

Cheers,

Tyron