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Log Reference

S9300, S9300E, and S9300X V200R010C00

This document provides the explanations, causes, and recommended actions of logs on the product.
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ADPIPV4/4/CPCAR_TTL1_DROP: The number of packets sent to the CPU exceed the threshold [ULONG].(SLOT=[STRING], CPCAR TYPE=[STRING], DiscardPacketCount=[STRING], Reason=[STRING]).


The device receives a large number of TTL-expired packets, which are then discarded because the packet rate exceeds CPCAR settings.


Parameter Name Parameter Meaning
SLOT Indicates the slot ID.
CPCAR TYPE Indicates the CPCAR type.
  • CPCAR_TTL1: TTL-expired packets will be discarded.
DiscardPacketCount Indicates the number of discarded packets.
Reason Indicates the reasons for packet discarding.
  • A routing loop may occur: A routing loop may occur on the network. As a result, a large number of TTL-expired packets are received by the device and then discarded because the packet rate exceeds CPCAR settings.

Possible Causes

Cause 1: A routing loop occurs on the network.

Cause 2: The device is attacked by TTL-expired packets.


  1. Run the display cpu-defend statistics command in the user view multiple times to check whether the number of discarded TTL-expired packets continuously increases.

    • If the number of discarded TTL-expired packets does not continuously increase and current services are normal, no action is required.
    • If the number of discarded TTL-expired packets continuously increases, go to step 2.

  2. Check whether a routing loop occurs on the network. If so, eliminate the loop.
  3. Check whether the device is under an TTL-expired packet attack. If so, you are advised to configure the CPU attack defense policy to reduce the number of TTL-expired packets sent to the CPU and identify the attack source based on the source address and port information of attack packets.
  4. If the alarm persists after the routing loop and attack packets are removed, collect alarm information, log information, and configuration information and contact technical support personnel. For details, see Troubleshooting-Information Collection-Collecting Diagnostic Information.
Updated: 2019-08-21

Document ID: EDOC1000142069

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