Layer 3 Loop Detection on iMaster NCE-TXN

Hello, everyone!

I would like to share a method for enabling Layer 3 Loop Detection in Mobile communication bearer network on OptiX PTN 7900 equipment on Huawei’s new Cloud-based iMaster NCE-TXN

Description

    OptiX PTN 7900  is a new generation metropolitan optical transport platform that transmits packets. It is used to build at the core and aggregation layers of a metropolitan transport network for bearer networks for mobile communication, and enterprises.  Any service interruption due to loop creation can lead to network disaster. For avoiding L3 loop, we need to apply a method to detect Loop.

Usage Scenario

    The Layer 3 loop detection function detects whether a loop exists on a network. If a routing loop is detected, the device should report an alarm. so that you can take rapid measures to ensure proper service running.

Prerequisites

You need to have the Operator Group or higher rights.

Tools, Equipment, and Materials

• iMaster NCE TXN

• PTN7900 V100R012C00

Procedure

1.       In the NE Explorer, choose Configuration > Control Plane Configuration > Three-layer Loop Detection from the function tree. On the Three-layer Loop Detection tab on the right, you can view ROUTE_LOOP_ALM alarm threshold.

2.       In the Three-layer Loop Detection page, set loopDetectEn to Apply.

Parameter description

Detection period (s)

When TTL exceeded packets statistics are collected within Detection period (Value range: 5 to 3600

Default value: 60)

Alarm threshold (%)  [Value range: 1 to 100 Default value: 10]

ROUTE_LOOP_ALM alarm is reported, when conditions (Y/X<Z, Y>0, and X>0) are met,

X indicates the collected statistics on packets dropped because the TTL expires in the preceding detection period, which is large in the loop start phase because a large amount of traffic is sent.

Y indicates the collected statistics on packets dropped because the TTL expires in the current detection period, which is small because traffic drop in the current period completes and only some protocol packets whose TTL expires are sent on the network.

Z indicates the alarm threshold. 

End remarks

To ensure network reliability, loop avoidance is necessary but needs to plan this activity under approved activity window and with Huawei GTAC support