The Echo Reply is an ICMP message generated in response to an ICMP Echo Request message, and is mandatory for all hosts and routers.
Message Format:
| 00 |
01 |
02 |
03 |
04 |
05 |
06 |
07 |
08 |
09 |
10 |
11 |
12 |
13 |
14 |
15 |
16 |
17 |
18 |
19 |
20 |
21 |
22 |
23 |
24 |
25 |
26 |
27 |
28 |
29 |
30 |
31 |
| Type = 0 |
Code = 0 |
Header Checksum |
|
Identifier |
<p align="center">Sequence Number |
</table>
|
Data ::: |
</table>
- Type and Code must be set to 0.
- The Identifier and Sequence Number can be used by the client to manage which Echo Requests are associated with the Echo Replies.
- The Data received by the Echo Request must be entirely included in the Echo Reply.
