Reference Guide

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20
ICMP Message Types
This chapter lists and describes the possible ICMP Message Type. The first three columns list
the possible symbol or type/code. For example, you would receive a ! or 03 as an echo reply
from a ping.
Table 20-2. ICMP Messages and their definitions
Symbol Type Code Description Query Error
• Timeout (no reply)
! 0 3 echo reply •
U 3 destination unreachable:
0 network unreachable •
1 host unreachable •
2 protocol unreachable •
3 port unreachable •
4 fragmentation needed but don’t fragment bit set •
5 source route failed •
6 destination network unknown •
7 destination host unknown •
8 source host isolated (obsolete) •
9 destination network administratively prohibited •
10 destination host administratively prohibited •
11 network unreachable for TOS •
12 host unreachable for TOS •
13 communication administratively prohibited by
filtering
•
14 host precedence violation •
15 precedence cutoff in effect •
C 4 0 source quench •
5 redirect •
0 redirect for network •
1 redirect for host •
2 redirect for type-of-service and network •