Introduction To Ldt; Configuring Ldt; Establishing The Configuration Task - Huawei Quidway S9300 Configuration Manual

10 LDT Configuration

10.1 Introduction to LDT

This section describes the concept of LDT.
After the LDT function is configured on an interface, the interface sends loopback detection
packets to detect loops in the local VLAN.
If the S9300 detects that the broadcast packets sent from an interface can be received by other
interfaces on the S9300, the S9300 considers that loops exist on the network of this interface.
In this case, the S9300 sends a trap message to the user and records the event in the log. In
addition, the S9300 sets the status of the interface according to the operation mode of the
interface. By default, the S9300 sets the interface to the Blocking state. The blocked interface
cannot forward packets other than BPFUs, ARP packets, and ICMP packets. The interface is
thus controlled and the influence of the loops on the entire network is minimized.

10.2 Configuring LDT

This section describes how to configure the LDT function.

10.2.1 Establishing the Configuration Task

10.2.2 Enabling LDT Globally
10.2.3 Enabling LDT in a VLAN
10.2.4 Enabling LDT Control on an Interface
10.2.5 (Optional) Disable LDT on an Interface
10.2.6 (Optional) Setting the LDT Interval on an Interface
10.2.7 (Optional) Setting the Recovery Time of a Blocked Interface
10.2.8 Checking the Configuration
10.2.1 Establishing the Configuration Task
Applicable Environment
When packets sent from an interface are sent back to local device through another interface, it
indicates that a loop exists on the interface. Loops may cause broadcast storms. The LDT function
is used to detect loops on the interfaces of the S9300.
After LDT is enabled for Ethernet interfaces on the S9300, the S9300 periodically detects loops
on each Ethernet interface. If a loop is detected on an Ethernet interface, the S9300 sets the state
of the interface to LDT.
Pre-configuration Tasks
None.
10-2 Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
Quidway S9300 Terabit Routing Switch
Configuration Guide - Ethernet
Issue 03 (2009-08-20)