Table 86: ICMP Message Classes, Types and Codes
Message
Class
|
Type Value
|
Message
Name
|
Summary
Description of Message Type
|
Defining
RFC Number
|
ICMPv4
Error Messages
|
3
|
Destination
Unreachable
|
Indicates that a datagram could
not be delivered to its destination. The Code value provides
more information on the nature of the error.
|
792
|
4
|
Source
Quench
|
Lets a congested
IP device tell a device that is sending it datagrams to slow down the
rate at which it is sending them.
|
792
|
5
|
Redirect
|
Allows a router to inform a host
of a better route to use for sending datagrams.
|
792
|
11
|
Time
Exceeded
|
Sent when a
datagram has been discarded prior to delivery due to expiration of its
Time To Live field.
|
792
|
12
|
Parameter
Problem
|
Indicates a miscellaneous problem
(specified by the Code value) in delivering a datagram.
|
792
|
ICMPv4
Informational Messages
(part 1 of 2)
|
0
|
Echo
Reply
|
Sent in reply
to an Echo (Request) message; used for testing connectivity.
|
792
|
8
|
Echo (Request)
|
Sent by a device to test connectivity
to another device on the internetwork. The word Request
sometimes appears in the message name.
|
792
|
9
|
Router
Advertisement
|
Used by routers
to tell hosts of their existence and capabilities.
|
1256
|
10
|
Router
Solicitation
|
Used by hosts to prompt any listening
routers to send a Router Advertisement.
|
1256
|
13
|
Timestamp
(Request)
|
Sent by a device
to request that another send it a timestamp value for propagation time
calculation and clock synchronization. The word Request
sometimes appear in the message name.
|
792
|
14
|
Timestamp
Reply
|
Sent in response to a Timestamp
(Request) to provide time calculation and clock synchronization
information.
|
792
|
15
|
Information
Request
|
Originally
used to request configuration information from another device. Now obsolete.
|
792
|
ICMPv4
Informational Messages
(part 2 of 2)
|
16
|
Information
Reply
|
Originally used to provide configuration
information in response to an Information Request message. Now
obsolete.
|
792
|
17
|
Address
Mask Request
|
Used to request
that a device send a subnet mask.
|
950
|
18
|
Address
Mask Reply
|
Contains a subnet mask sent in
reply to an Address Mask Request.
|
950
|
30
|
Traceroute
|
Used to implement
the experimental enhanced traceroute utility.
|
1393
|
ICMPv6
Error Messages
|
1
|
Destination
Unreachable
|
Indicates that a datagram could
not be delivered to its destination. Code value provides more
information on the nature of the error.
|
2463
|
2
|
Packet
Too Big
|
Sent when a
datagram cannot be forwarded because it is too big for the maximum
transmission unit (MTU) of the next hop
in the route. This message is needed in IPv6 and not IPv4 because in
IPv4, routers can fragment oversized messages, while in IPv6 they cannot.
|
2463
|
3
|
Time Exceeded
|
Sent when a datagram has been
discarded prior to delivery due to the Hop Limit field being
reduced to zero.
|
2463
|
4
|
Parameter
Problem
|
Indicates a
miscellaneous problem (specified by the Code value) in delivering
a datagram.
|
2463
|
ICMPv6
Informational Messages
|
128
|
Echo Request
|
Sent by a device to test connectivity
to another device on the internetwork.
|
2463
|
129
|
Echo
Reply
|
Sent in reply
to an Echo (Request) message; used for testing connectivity.
|
2463
|
133
|
Router
Solicitation
|
Prompts a router to send a Router
Advertisement.
|
2461
|
134
|
Router
Advertisement
|
Sent by routers
to tell hosts on the local network the router exists and describe its
capabilities.
|
2461
|
135
|
Neighbor
Solicitation
|
Sent by a device to request the
layer two address of another device while providing its own as well.
|
2461
|
136
|
Neighbor
Advertisement
|
Provides information
about a host to other devices on the network.
|
2461
|
137
|
Redirect
|
Redirects transmissions from
a host to either an immediate neighbor on the network or a router.
|
2461
|
138
|
Router
Renumbering
|
Conveys renumbering
information for router renumbering.
|
2894
|