icmp <subcommands>

These commands are used for the Internet Control Message Protocol service.

icmp echo [ON | off]

(B) Display or set the flag controlling the asynchronous display of ICMP Echo Reply packets. This flag must be on for pings to work. Default is on.

icmp quench [on | OFF]

With 'icmp quench off', when a packet is received and memory available < threshold, the packet will be dropped (i.e., no quench or anything.) The higher protocol layers will keep track of re-transmitting the dropped packets.

With 'icmp quench on', when packets are received and the high water mark for dynamically allocatable storage has been exceeded, JNOS40 submits an ICMP Source Quench to the originator. Usually, before the originator will have reacted to the source quench, JNOS40's dynamically allocatable storage will have been exhausted. What happens after that is uncertain, but it is assumed to be unfavorable. Many tcp/ip implementations don't even respond to Source Quenches at all. See also 'memory threshold command.'

Default is OFF.

icmp status

Display statistics about the Internet Control Message Protocol (ICMP), including the number of ICMP messages of each type sent or received.

icmp timeexceed [<ON | off>]

Allows 'time exceeded' message to be sent when the ttl of an ip packet to be routed becomes zero. When turned OFF, no message is sent which allows the system to become invisible for 'traceroutes', etc.

icmp trace [on | off]

(B) Display or set the flag controlling the display of ICMP error messages. These informational messages are generated by Internet routers in response to routing, protocol or congestion problems. This only functions when in console mode. Default is off.