What are the proper contents of an ICMP message? (Buffer, Don’t Fragment, etc..)

icmpnetworking

I'm creating a Tracert program and am wondering if the value "buffer" used in the Ping payload really matters. Can it be anything, or do routers respond differently based on the contents of the buffer?

What about the other parts of an ICMP ping message? Don't Fragment, etc…

http://msdn.microsoft.com/en-us/library/ms144962.aspx

I found one sample that sets the buffer like this:

    byte[] Buffer
    {
        get
        {
            if (_buffer == null)
            {
                _buffer = new byte[32];
                for (int i = 0; i < Buffer.Length; i++)
                {
                    _buffer[i] = 0x65;
                }
            }
            return _buffer;
        }
    }

Best Answer

No, the data section of an ICMP echo is not meaningful.

It serves as a means to make the request and reply packets larger (potentially past the point of fragmentation, the path's MTU) to test network conditions, but is not handled in any way by ICMP implementations (aside from being copied into the echo reply by a responding device).

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