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Webcast-Catalyst9k
Bronze

icmp unreachable messages and ping codes

Hi every body.

My book says when we use ping, we could receive five poossible responses identified by code in the output. For example:

! echo reply received

. nothing was received, ping timed out

U Icmp unreachable( destination )

N icmp unreahable( network)

M can not fragment the packet

? unknown packet received.

=================================

Let say we are not using ping, we are using wireshark.

we can capture Icmp messages exchanged between hosts when trouble occurs .

According to book, ICmp unreachable messages can includes fives seperate unreacable codes that further identify why the packet cannot be delivered.

These codes are:

Network unreachable:

host unreacable

Can't fragment

protocol unreachable

port unreachable

what are the alphabitical codes to represent these above messages?

thanks a lot.

2 REPLIES
Bronze

Re: icmp unreachable messages and ping codes

I did some research and found something. I am posting here if someone might be interested, may find it useful.

The codes are not represented by alphabets as is the case in ping. Rather they are represented by digits.

Below is the link.

http://www.tcpipguide.com/free/t_ICMPv4DestinationUnreachableMessages-3.htm#Table_89

Hall of Fame Super Blue

Re: icmp unreachable messages and ping codes

Sarah

Just for your reference in case you haven't seen this here is the full list of ICMP type and codes -

http://www.iana.org/assignments/icmp-parameters

Jon

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