Enabling sending ICMP time exceeded messages
About ICMP time exceeded messages
A device sends ICMP time exceeded messages by following these rules:
The device sends the source an ICMP TTL exceeded in transit message when the following conditions are met:
The received packet is not destined for the device.
The TTL field of the packet is 1.
When the device receives the first fragment of an IP datagram destined for it, it starts a timer. If the timer expires before all the fragments of the datagram are received, the device sends an ICMP fragment reassembly time exceeded message to the source.
Restrictions and guidelines
If the ICMP time exceeded message sending is disabled, the device does not send ICMP TTL exceeded in transit messages. However, it can still send ICMP fragment reassembly time exceeded messages.
Procedure
Enter system view.
system-view
Enable sending ICMP time exceeded messages.
ip ttl-expires enable
By default, the sending of ICMP time exceeded messages is disabled.