Dasan V5808 - ICMP Message Control; Blocking Echo Reply Message; ICMP Message Structure

UMN:CLI User Manual
V5808
244
7.17 ICMP Message Control
ICMP stands for Internet Control Message Protocol. When it is impossible to transmit data
or configure route for data, ICMP sends error message about it to host. The first 4 bytes
of all ICMP messages are same, but the other parts are different according to type field
value and code field value. There are fifteen values of field to distinguish each different
ICMP message, and code field value helps to distinguish each type in detail.
The following table shows explanation for fifteen values of ICMP message type.
Type
Value
Type
Value
ICMP_ECHOREPLY
0
ICMP_DEST_UNREACH
3
ICMP_SOURCE_QUENCH
4
ICMP_REDIRECT
5
ICMP_ECHO
8
ICMP_TIME_EXCEEDED
11
ICMP_PARAMETERPROB
12
ICMP_TIMESTAMP
13
ICMP_TIMESTAMPREPLY
14
ICMP_INFO_REQUEST
15
ICMP_INFO_REPLY
16
ICMP_ADDRESS
17
ICMP_ADDRESSREPLY
18
-
-
Tab. 7.1 ICMP Message Type
The following figure shows simple ICMP message structure.
0 7 15 16 31
8-bit Type
8-bit Code
16-bit Checksum
(Contents Depend on Type and Code)
Fig. 7.16 ICMP Message Structure
It is possible to control ICMP message through user’s configuration. You can configure to
block the echo reply message to the partner who is doing ping test to device and interval
to transmit ICMP message.
7.17.1 Blocking Echo Reply Message
It is possible to configure block echo reply message to the partner who is doing ping test
to switch. To block echo reply message, use the following command.
Command
Mode
Description
ip icmp ignore echo all
Global
Blocks echo reply message to all partners who are
taking ping test to device.
ip icmp ignore echo broadcast
Blocks echo reply message to partner who is taking
broadcast ping test to device.