Internet Control Message Protocol (Icmp) - Allied Telesis SwitchBlade x908 Series Software Reference Manual

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 Message Type
Echo reply (0)
Destination unreachable (3)
Source Quench (4)
Redirect (5)
Echo request (8)
Router Advertisements (10)
Time to Live Exceeded (11)
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
Control List (ACL)
C613-50007-01 REV B
Device Response
This is used to implement the ping command. Your device
sends out an echo reply in response to an echo request.
This message is sent when your device drops a packet
because it did not have a route to the destination.
Your device sends this message when it must drop a packet
due to limited internal resources. This could be because the
source was sending data too fast to be forwarded.
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.
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.
These are Router Discovery Protocol messages. If Router
Discovery is enabled, your device sends these to announce
the IP addresses of the sending interface.
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.
Commands.
Software Reference for SwitchBlade® x908, x900 and x600 Series Switches
TM
AlliedWare Plus Operating System - Software Version 5.3.1
Internet Protocol (IP) Addressing and Protocols
Chapter 49, Access
22.9