BER & MW Loops

ahXing · Created Nov 28, 2020 23:29:31

Hi!

You've asked:

1) "what the BER and how to solve it ?"

2) "what the Loops ? and how to use it in different alarms?"

First, BER = Bit Error Rate, the chance that a bit-error will occur.

BER is often expressed in scientific notation such as 10E-6: which means: "One in a million bits passing, there will be 1 bit error". So, the BER will tell you something how well a channel is.

Another practical example: traditional 2 Mbit/s circuit (E1): 2048 kbit/s - so each second, 2048000 bits will pass. With a BER of 10E-6, it is very likely 2 bits are wrong of those 2048000 bits that has passed.

How to solve this? Many approaches:

1) Improve the quality of the link. If a BER is very high (unusual high for your media) then something is wrong and you have to investigate. For a radio link, it means: "Increase the quality of your radio link - often by increasing power, with the hope your SNR (Signal to Noise Ratio) improves, hence - lowers the BER.

2) Implement FEC (Forward Error Correction) ... With BER = 10E-6 if you already know 1 out of a million bits will be wrong, then make sure you can detect and calculate the correct value (fix the error) of that wrong bit.

3) If you have a link with high BER (i.e. a lot of bits are going to be wrong - and you know it)... try to decrease the packetsize (i.e. sending only small groups of bits) and hope your higher level protocols can request a resend. By using only small packets, you hope - the amount of packets going through is still okay.

Loops...

By setting a 'loop' somewhere in the circuit, you needed only one BER tester at one end. A loop, is like a mirror: all the traffic sent, is being reflected back where it came from. So! as troubleshooting, you could measure the BER, set a loop and if the data came back clean (without errors) then you know... 'until the loop and back, it is fine'.

Then you move the loop further down the line... until you see a sudden increase of errors... if that happens, you know, something is wrong between loop1 and loop2... and you can narrow down your investigation.

Hope this helps.

ahXing

wissal · Created Nov 28, 2020 20:29:46

Hello,

If a BER tester is available, the BER tester can be used to test whether E1 services are available.

Prerequisites

The NE must be configured with E1 services, and the E1 services must be transmitted through the DDF.

Tools, Equipment, and Materials

NCE
Web LCT also supports this operation and the steps are the same as those on the NCE.
BER tester
For a test of CES services in CESoPSN mode, a BER tester supporting Nx64 Kbit/s timeslot setting is necessary.

Procedure

On the DDF at the central site, connect the BER tester to the first E1 port of the IDU.

The BER tester indicates the AIS alarm.
Figure 1 Connecting the BER tester
On the NMS, perform an inloop for the corresponding E1 port at the remote site.
1. Select the PDH interface board in the Object Tree.
2. In the Function Tree, choose Configuration > PDH Interface.
3. Select By Function and select Tributary Loopback from the drop-down menu.
4. In Tributary Loopback, select Inloop.
5. Click Apply.
  The Confirm dialog box is displayed.
6. Click OK.
  The Confirm dialog box is displayed.
7. Click OK.
  The Operation Result dialog box is displayed.
8. Click Close.
Test the bit errors for two minutes.
There should be no bit errors.
For a test of CES services, it is necessary to configure 64 Kbit/s timeslots on a BER tester to align with the timeslots carrying CES services.
Release the inloop set in 2.
1. Select the PDH interface board in the Object Tree.
2. In the Function Tree, choose Configuration > PDH Interface.
3. Select By Function and select Tributary Loopback from the drop-down menu.
4. In Tributary Loopback, select Non-Loopback.
5. Click Apply.
  The Confirm dialog box is displayed.
6. Click OK.
  The Confirm dialog box is displayed.
7. Click OK.
  The Operation Result dialog box is displayed.
8. Click Close.
Repeat 1 through 4 to test all other E1 ports.

Routing Loop

A routing loop refers to the situation where packets are forwarded back-and-forth between two or more routers until the time to live (TTL) becomes 0 when they are discarded. Routing loops deteriorate network performance and must be prevented.

Possible Adverse Impact

A routing loop, especially a routing loop lasting for a long period of time, results in failure in forwarding packets to correct destinations, and may cause link congestion or even the partial breakdown of a network.

Possible Causes

Temporary loops are generated during route convergence.
Some algorithms, such as the Routing Information Protocol (RIP), have defects.
Information that can prevent routing loops is lost during route import.
Loop risks are introduced by aggregation route advertisement.
Some network configurations are incorrect.

Preventive Measures

Use routing protocols with complete routing loop avoidance mechanisms, such as Open Shortest Path First (OSPF), and Intermediate System to Intermediate System (IS-IS).
Set the costs of imported routes to values greater than possible values on actual networks.
Configure black-hole routes for aggregation routes.
Ensure that network configurations are correct.

More detail :

https://support.huawei.com/hedex/hdx.do?docid=EDOC1100113421&lang=en

Thanks

ahXing · Created Nov 28, 2020 23:29:31

Hi!

You've asked:

1) "what the BER and how to solve it ?"

2) "what the Loops ? and how to use it in different alarms?"

First, BER = Bit Error Rate, the chance that a bit-error will occur.

BER is often expressed in scientific notation such as 10E-6: which means: "One in a million bits passing, there will be 1 bit error". So, the BER will tell you something how well a channel is.

Another practical example: traditional 2 Mbit/s circuit (E1): 2048 kbit/s - so each second, 2048000 bits will pass. With a BER of 10E-6, it is very likely 2 bits are wrong of those 2048000 bits that has passed.

How to solve this? Many approaches:

1) Improve the quality of the link. If a BER is very high (unusual high for your media) then something is wrong and you have to investigate. For a radio link, it means: "Increase the quality of your radio link - often by increasing power, with the hope your SNR (Signal to Noise Ratio) improves, hence - lowers the BER.

2) Implement FEC (Forward Error Correction) ... With BER = 10E-6 if you already know 1 out of a million bits will be wrong, then make sure you can detect and calculate the correct value (fix the error) of that wrong bit.

3) If you have a link with high BER (i.e. a lot of bits are going to be wrong - and you know it)... try to decrease the packetsize (i.e. sending only small groups of bits) and hope your higher level protocols can request a resend. By using only small packets, you hope - the amount of packets going through is still okay.

Loops...

By setting a 'loop' somewhere in the circuit, you needed only one BER tester at one end. A loop, is like a mirror: all the traffic sent, is being reflected back where it came from. So! as troubleshooting, you could measure the BER, set a loop and if the data came back clean (without errors) then you know... 'until the loop and back, it is fine'.

Then you move the loop further down the line... until you see a sudden increase of errors... if that happens, you know, something is wrong between loop1 and loop2... and you can narrow down your investigation.

Hope this helps.

ahXing

Mohamed_Ahmed · Created Nov 30, 2020 09:25:31

Posted by wissal at 2020-11-28 20:29 Hello,If a BER tester is available, the BER tester can be used to test whether E1 services are a ...

thanks Wissal

Mohamed_Ahmed · Created Nov 30, 2020 09:26:16

Posted by ahXing at 2020-11-28 23:29 Hi! You've asked: 1) "what the BER and how to solve it ?"

thank you very much for detailed info

Lianet · Created Jan 8, 2021 01:30:45

Interesting question.

user_4034933 · Created Jan 19, 2021 15:30:49

Thanks for sharing

faysalji · Created Nov 23, 2021 12:16:13

Solutions are already provided, good.

Mohamed_Ahmed · Created Nov 24, 2021 16:31:10

Well done.solved

Saqib123 · Created Nov 24, 2021 18:37:20

Issue Resolved.
Thank You

BER & MW Loops

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Preventive Measures

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BER & MW Loops

Recommended answer

Prerequisites

Tools, Equipment, and Materials

Procedure

Routing Loop

Possible Adverse Impact

Possible Causes

Preventive Measures

Third Party’s Trade Secret

My Followers