Why is LDP loop detection unnecessary


LSPs are generated strictly based on IP routing. Routing protocols such as OSPF and IS-IS have a mechanism to ensure loop-free routes. Therefore, LDP loop detection is unnecessary.

Other related questions:
Why is LDP loop detection not required on the AR
LDP is generated based on IP routes. A routing protocol such as IS-IS or OSPF can avoid routing loop generation, so LDP loop detection is not required any more.

Loop prevention and breaking on S series switch
For S series switches except S1700 switches, use any of the following methods to remove loops: 1. Configure features such as STP, RSTP, MSTP, VBST,RRPP, and SEP to prevent loops. 2. Bundle dual physical links into a single logical link to prevent loops while implementing redundancy and increasing bandwidth. 3. Configure the switch to transparently transmit packets of different VLANs along different paths. 4. Enable loop detection and loopback detection to detect loops on the switch or downstream network connected to the switch, and configure the switch to take the preconfigured action to remove loops. Fixed switches only support loopback detection.

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.

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