Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 633)

Internet Protocol (IP) Addressing and Protocols
Software Reference for x310 Series Switches
C613-50046-01 REV A AlliedWare Plus TM Operating System - Version 5.4.4C 24.9
Internet Control Message Protocol (ICMP)
The Internet Control Message Protocol (ICMP) allows networking devices to send
information and control messages to other devices or hosts. Your device implements all
non-obsolete ICMP functions.
The following table lists the ICMP messages implemented by your device.
ICMP messages are enabled on all interfaces by default. You can control the flow of ICMP
messages across different interfaces using the access-list commands. See
Chapter 34,
IPv4 Hardware Access Control List (ACL) Commands and Chapter 35, IPv4 Software
Access Control List (ACL) Commands .
ICMP Message Type Device Response
Echo reply (0) This is used to implement the ping command. Your
device sends out an echo reply in response to an echo
request.
Destination unreachable (3) This message is sent when your device drops a packet
because it did not have a route to the destination.
Redirect (5) Your device issues this message to inform a local host that
its target is located on the same LAN (no routing is
required) or when it detects a host using a non-optimal
route (usually because a link has failed or changed its
status).
For example, if your device receives a packet destined to
its own MAC address, but with a destination IP address of
another host in the local subnet, it returns an ICMP
redirect to the originating host.
ICMP redirects are disabled on interfaces on which local
proxy ARP is enabled.
Echo request (8) This is related to echo replies. If your device receives an
echo request, it sends an echo reply. If you enter the ping
command, your device generates echo requests.
Router Advertisements (10) These are Router Discovery Protocol messages. If Router
Discovery is enabled, your device sends these to
announce the IP addresses of the sending interface.
Time to Live Exceeded (11) If the TTL field in a packet falls to zero, your device sends
this message.This occurs when there are too many hops
in the path that a packet is traversing.