Alarms in SDH

[nguyen van toan]

Hello Huub,

I have confusion about alarms in SDH that I your help.

1. Assume I connect SDH equipment to the tester and I will
loopback at VC12 at SDH equipment.
At the tester I trigger AU-AIS. Addition to detecting AU-AIS,
does SDH equipment detect HP-TIM, TU-AIS, LOM ?

2. Assume I performs SDH over Ethernet:

Tester (VC4 - bulk) --> STM-1 --> Tester interface --> SDHoE
(CEP) --> loopback at Ethernet interface. If I trigger MS-AIS (from
tester), can tester detects AU-AIS (on the received signal) ?

+==============+
+===================+
| | MS-AIS
| |
| SDH tester |============> | SDH over
Ethernet |====|
| |
| (CEP) | | LB at Ethernet
interface
| |<============
| |====|
| |
| |
+==============+
+===================+

Thanks,
Toan

[Huub van Helvoort]

Hello Toan,

You wrote:

> I have confusion about alarms in SDH that I your help.
>
> 1. Assume I connect SDH equipment to the tester and I will
> loopback at VC12 at SDH equipment.
> At the tester I trigger AU-AIS. Addition to detecting AU-AIS,
> does SDH equipment detect HP-TIM, TU-AIS, LOM ?

Because of the detection of AU-AIS I expect only TU-AIS reported,
HP-TIM, LOM may be detected but not reported because they are not
the probable cause.

> 2. Assume I performs SDH over Ethernet:
> Tester (VC4 - bulk) --> STM-1 --> Tester interface --> SDHoE
> (CEP) --> loopback at Ethernet interface. If I trigger MS-AIS (from
> tester), can tester detects AU-AIS (on the received signal) ?

The tester will detect and report MS-AIS and consequently also
report AU-AIS.

Unfortunately your figure was corrupted.
(Maybe you used tabs or too long lines >75 char.).

> +==============+
> +===================+
> | | MS-AIS
> | |
> | SDH tester |============> | SDH over
> Ethernet |====|
> | |
> | (CEP) | | LB at Ethernet
> interface
> | |<============
> | |====|
> | |
> | |
> +==============+
> +===================+

Cheers, Huub.

--
reply to hhelvooort with 2 'o's
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[nguyen van toan]

Hello Huub,

1. Repeat the problem above, is there any alarm suppression in SDH
(I mean if the equipment detects and reports AU-AIS, it will not
detect TU-AIS) ?
If my thought is not correct, can you explain me this problem more
details ?

2. In the 2nd problem, I think the tester will detect and report AU-
AIS and it will also report MS-RDI, not MS-AIS as you replied. Is it
right?
(it's difficult to draw a picture here, you can imagine I had an
equipment SoE (Circuit emulation over Ethernet), SDH interface
connects to tester and Ethernet interface will be loopback, and I
trigger MS-AIS from tester).

Thanks,
Toan

[Huub van Helvoort]

Hello Toan,

You replied:

AU-AIS is a signal that consists of all-ONEs.
Consequently, if the AU4 was sub-structured all termination functions
of the substructure will receive an all-ONEs signal and detect TU-AIS.
If the AU4 was not substructured only AU-AIS will be detetced.

> 2. In the 2nd problem, I think the tester will detect and report AU-
> AIS and it will also report MS-RDI, not MS-AIS as you replied. Is it
> right?
> (it's difficult to draw a picture here, you can imagine I had an
> equipment SoE (Circuit emulation over Ethernet), SDH interface
> connects to tester and Ethernet interface will be loopback, and I
> trigger MS-AIS from tester).

The MS-RDI will be detected by the sink termination function that is
co-located at the source termination function that is configured to
send the MS-AIS.
The MS-AIS and AU-AIS will be detected at the far-end sink termination
functions (at the other side of the loop).

Best regards, Huub.