ICMP ERROR MESSAGES
Hi guys, as we know ICMP is a common protocol in TCP/IP suite. It is
used conjunction with IP to provide diagnostics and control information
of IP packets.
ICMP included: ICMP
Messages, ICMP Error Messages, ICMP Query/ Information Messages,
Neighbor Discovery in IPv6,... And now, I'll talk recall about ICMP ERROR MESSAGES.
Firstly, I'll talk about Extended ICMP & Multipart Messages.
[RFC4884] specifies a method for extending the ultility of ICMP
Messages by allowing an extension data structure to be appended to them.
The extension data structure includes an extension header and extension
objects that may contain a variable amount of data.When this extensions
are used, the ICMP payload area containing the original datagram must
be at least 128 bytes long.
Secondly, I'll present Destination Unreachable ( ICMPv4 type 3, ICMPv6 type 1) and Packet Too Big (ICMPv6 type2).
This type of messages is used to indicate that there are errors while delivered datagram all the way. There are 3 in 16 code of error are used. It's Host Unreachable (code1), Port Unreachable(code3), Fragmentation Required/ Don't Fragment Specified (code4), and Communication Administratively Prohibited (code 13).
* Host Unreachable and ICMPv6 Address Unreachable: this message is generated by a router or a host when it is required to send an IP datagram to host using direct delivery host but for some reason it can not reach to it.
* ICMPv6 No Router to Destination (Code 0): this message is indicated when a IP datagram can reach to destination by no router is present.
* ICMPv4 Packets Too Big (PTB): If the datagram does not fit into the MTU in use on the selected outgoing network interface, the datagram must be fragmented. If Dont Fragmet field was set in its IP Header, it will be dropped.
Then, I talk about Redirect
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