
icmp <subcommands>

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

     

    icmp echo [ON | off]

     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,
     JNOS submits an ICMP Source Quench to the originator.  Usually,
     before the originator will have reacted to the source quench,
     JNOS'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 ON.
    

    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 [0|1|2]

     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
     0 (off).  A trace value of 1 traces all icmp packets, while a
     value of 2 traces only icmp types known to Jnos.

     

