Section B-2. ICMP Type and Code Numbers


B-2. ICMP Type and Code Numbers

The Internet Control Message Protocol (ICMP) transports error or control messages between routers and other devices. An ICMP message is encapsulated as the payload in an IP packet. Figure B-3 shows the ICMP message format. Notice that in the case of an error condition, the first 8 bytes (64 bits) of the original datagram causing the error are included in the ICMP message. This provides the protocol and port numbers of the original message to be seen, making troubleshooting easier.

Figure B-3. ICMP Message Format


ICMP type codes are registered with the IANA. The information presented here is reproduced with permission from the IANA. For the most current ICMP type code number assignment information, refer to www.iana.org/numbers.htm under the "ICMP Type" link.

Table B-2 shows the assigned ICMP type numbers, ICMP codes (where applicable), a brief description, and a reference to an RFC.

Table B-2. Assigned ICMP Type Numbers, Codes, Descriptions, and Associated RFCs

Type

Code

Name

Reference

0

 

Echo Reply

RFC 792

1

 

Unassigned

 

2

 

Unassigned

 

3

 

Destination Unreachable

RFC 792

 

0

Net Unreachable

 
 

1

Host Unreachable

 
 

2

Protocol Unreachable

 
 

3

Port Unreachable

 
 

4

Fragmentation Needed and Don't Fragment Was Set

 
 

5

Source Route Failed

 
 

6

Destination Network Unknown

 
 

7

Destination Host Unknown

 
 

8

Source Host Isolated

 
 

9

Destination Network Is Administratively Prohibited

 
 

10

Destination Host Is Administratively Prohibited

 
 

11

Destination Network Unreachable for Type of Service

 
 

12

Destination Host Unreachable for Type of Service

 
 

13

Communication Administratively Prohibited

RFC 1812

 

14

Host Precedence Violation

RFC 1812

 

15

Precedence Cutoff in Effect

RFC 1812

4

 

Source Quench

RFC 792

5

 

Redirect

RFC 792

 

0

Redirect Datagram for the Network (or Subnet)

 
 

1

Redirect Datagram for the Host

 
 

2

Redirect Datagram for the Type of Service and Network

 
 

3

Redirect Datagram for the Type of Service and Host

 

6

 

Alternate Host Address

 
 

0

Alternate Address for Host

 

7

 

Unassigned

 

8

 

Echo

RFC 792

9

 

Router Advertisement

RFC 1256

10

 

Router Solicitation

RFC 1256

11

 

Time Exceeded

RFC 792

 

0

Time to Live Exceeded in Transit

 
 

1

Fragment Reassembly Time Exceeded

 

12

 

Parameter Problem

RFC 792

 

0

Pointer Indicates the Error

 
 

1

Missing a Required Option

RFC 1108

 

2

Bad Length

 

13

 

Timestamp

RFC 792

14

 

Timestamp Reply

RFC 792

15

 

Information Request

RFC 792

16

 

Information Reply

RFC 792

17

 

Address Mask Request

RFC 950

18

 

Address Mask Reply

RFC 950

19

 

Reserved (for Security)

 

20 to 29

 

Reserved (for Robustness Experiment)

 

30

 

Traceroute

RFC 1393

31

 

Datagram Conversion Error

RFC 1475

32

 

Mobile Host Redirect

 

33

 

IPv6 Where-Are-You

 

34

 

IPv6 I-Am-Here

 

35

 

Mobile Registration Request

 

36

 

Mobile Registration Reply

 

37

 

Domain Name Request

 

38

 

Domain Name Reply

 

39

 

SKIP

 

40

 

Photuris

 
 

0

Reserved

 
 

1

Unknown Security Parameters Index

 
 

2

Valid Security Parameters, but Authentication Failed

 
 

3

Valid Security Parameters, but Decryption Failed

 

41 to 255

 

Reserved

 




Cisco Field Manual. Catalyst Switch Configuration
Cisco Field Manual. Catalyst Switch Configuration
ISBN: 1587050439
EAN: N/A
Year: 2001
Pages: 150

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