ip ttl-expires enable
Use ip ttl-expires enable to enable sending ICMP time exceeded messages.
Use undo ip ttl-expires enable to disable sending ICMP time exceeded messages.
Syntax
ip ttl-expires enable
undo ip ttl-expires enable
Default
Sending ICMP time exceeded messages is disabled.
Views
System view
Predefined user roles
network-admin
mdc-admin
Usage guidelines
A device sends ICMP time exceeded messages by following these rules:
The device sends an ICMP TTL exceeded in transit message to the source 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 the device itself, 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.
A device disabled from sending ICMP time exceeded messages does not send ICMP TTL exceeded in transit messages but can still send ICMP fragment reassembly time exceeded messages.
Examples
# Enable sending ICMP time exceeded messages.
<Sysname> system-view [Sysname] ip ttl-expires enable