SLIP on PCM Links

[cpux10]

Hi,

We have a 9-LIM system on TSW SP5, in which some of the LIMs are on remote locations.

The problem I'm facing is that I encounter SLIP alarms on some of my PCM links (seen in GJLSP), where these SLIPs lead to DIST MARK in that PCM link and sometimes a "25 SLIP ON GROUP JUNCTOR LINE" alarm.

The strange thing for me is that this is ONLY seen on PCM links that are in a remote LIM with ELU31 boards. LIMs that don't have ELU31 boards never have SLIP alarms. LIMs on the main site with ELU31 also never have SLIP alarms.

Does this have anything to do with the ELU31 sync rings or something related?

I would appreciate any thoughts or suggestions...

 

[TBLuk]

I don't think the ELU31s should be related to PCM slips, as the ring sync is to keep the ELU31s within the same base station group in sync - not the LIMs.

How do the remote LIMs connect to the GSM? Has the network provider done checks to ensure there are no issues?

Is it intermittent? Does the LIM still function properly with the code 25s?

If so, it's possibly worth doing some faultfinding in swapping cards with a known working LIM (if downtime is available)
i.e. swap a GJUL with a known stable LIM, and monitor, do the same with a GJUG

 

[cpux10]

Thanks for the reply TBLuk,

The remote LIMs are connected to the GSM using SDH equipment...

I am thinking of another reason for the problem; I once saw someone saying on the forum that when using 120 ohm cabling, using the lowest position of the GJUG5 boards should be avoided! Now that I am checking, the PCM links which are causing me problems are all on the low positions of the GJUG5 (0-3, 0-7, 0-11, 0-15, 0-19).

Could this be causing the problem?

 

[whosrdaddy]

yes,

it is known that the 4th port GJUG5 board is less accurate (PCB design fault, something with resistors and voltage) and therefore more sensitive, espescially with SDH equipment. We faced the exact same problem.

You can do 2 things:

- contact Aastra about it and ask for replacement boards (There is a newer board for the LBP22 chassis where the design fault has been corrected).

- don't use the 4th port on the GJUG5

/Daddy

-----------------------------------------------------
What You See Is What You Get
Never underestimate tha powah of tha google!

 

[TBLuk]

would be good to know the ROF affected. I'd heard about this problem, but I'd never experienced the problem myself.
It does seem odd that it's more prolific with SDH connections, the frame structure should be the same for any G.703

 

[cpux10]

Thanks guys,

I don't have site access now, but I will try changing the GSMULT's to avoid using the 4th GJUG5 ports, and I'll get back with the results.

 

[ceejay55]

r8 gjug5

GJUG5
1 Reason for revision
Sync and slip problems in Link 3. Refer to:
(FR 114 425, MX 219 966, FR 114 426, MX 223088, FR 114 434, MX 220 719)
2 Technical solution
New PCB, TVM 113 5394 R3D with a number of changed/deleted or new components, see 13132-
ROF 137 5389/2.
Deviation description, 170 05-ROF 137 5389/2

 

[cpux10]

The problem is not seen anymore after changing the GJUG5 ports and not using the 4th port!

Thanks to everyone for helping.