What is LBDT and what are the differences between LBDT and LDT

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Loopback detection (LBDT) is different from loop detection (LDT) in the following aspects:

1. Application scenario: LBDT is applied on edge switches to prevent switch port fiber loopback or loopback of downstream loops to the port. LDT is applied on aggregation switches to detect loopbacks and loops on the entire Layer 2 network.

2. Configuration modes: LBDT is configured based on port modes. LDT is configured based on system modes.

3. Configuration command:
LBDT configuration command: loopback-detect enable. This command is used to enable loopback detection for ports.
LDT configuration command: loop-detection enable. Example: loop-detection enable vlan 200. This LDT configuration command is used to enable the VLAN-based loop detection function.

Other related questions:
How to set an interval for sending LBDT packets on an S series switches and how to distinguish LBDT packets sent by different interfaces
S series (except the S1700) and E series switches send LBDT packets in the following modes: 1. For fixed switches in V100R005 - An LBDT packet is sent every 100 ms. You can run the loopback-detect interval interval-time command to set an interval for sending LBDT packets. In the command, the value of interval-time ranges from 5 to 300, in seconds. By default, the interval for sending LBDT packets is 30s. - LBDT packets sent by different interfaces are distinguished based on protocol IDs carried in the packets. By default, the protocol ID of interface 1 on the S3700 is 0x606 and the protocol IDs of the other interfaces are incremented. You can run the loopback-detect protocol protocol-id command to manually set a protocol ID. Note that the protocol ID cannot be the same as an existing protocol ID. For details, see the command reference. 2. For fixed switches in V100R006 and later versions, modular switches, and E series switches - An LBDT packet is sent every 5s. You can run the loopback-detect packet-interval packet-interval-time command to set an interval for sending LBDT packets. The value of packet-interval-time ranges from 1 to 300, in seconds. - LBDT packets sent by different interfaces are distinguished based on interface indexes carried in the packets. Note: LBDT packets are sent frequently. Therefore, the CPU usage will increase if the LBDT function is enabled on all interfaces.

Why is no trap reported after LBDT detects a loop on an S series switches
After loopback detection is configured on an S series (except the S1700) or E series switch, an alarm is sent after a loop is detected only when the action is set to port-trap or trap using the loop-detection mode port-trap or loopback-detect action trap command.

Can protocol packets be sent if an interface with a loop detected is blocked on an S series switches
Can protocol packets be sent if an interface with a loop detected is blocked on an S series (except the S1700) or E series switch? For S series switches (except the S1700), the destination MAC address of LDT packets and tagged LBDT packets is all Fs. These packets cannot be sent through an interface if it is blocked. The destination MAC address of untagged LBDT packets is a BPDU MAC address. These packets can still be sent through an interface even if it is blocked. For E series switches, the destination MAC address of tagged LBDT packets is all Fs. These packets cannot be sent through an interface if it is blocked. The destination MAC address of untagged LBDT packets is a BPDU MAC address. These packets can still be sent through an interface even if it is blocked.

What are the differences between video and presentation?
Video refers to video streams captured by a camera and output from the HD OUT 1 port of an HD endpoint. Presentation refers to the computer desktop content, such as electronic forms, figures, and slides, which the local site shares with remote sites.

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