9 Replies Latest reply: Jul 18, 2017 8:39 AM by Micheline RSS

    ICMPv6 vs ICMPv6 ND


      Hi Everyone




      i don`t understand if we have ICMPv6  RFC 4443 why we need ICMPv6 ND RFC4861

      what is the difference between ICMPv6 vs ICMPv6 ND?



      i want to tell you something

      RFC language i don`t like it and i don`t understand anything inside it and i don`t understand exactly what the guy who write it need to say

      what do you advice me ?

      i think because it`s language is very difficult to me , do i don`t understand it

      does anything i can read else than RFC documents ?? in ospf eigrp ipv6 rip ipv4 etc ....

      sdavids5670 Micheline_Murphy daniel.dib

        • 1. Re: ICMPv6 vs ICMPv6 ND
          Steven Davidson

          RFC 4443 simply introduces and describes and defines ICMPv6 for IPv6.  In the very first couple of sentences (Introduction) it states:


          "Other documents may also introduce additional ICMPv6 message types, such as Neighbor Discovery messages [IPv6-DISC], subject to the general rules for ICMPv6 messages given in Section 2 of this document."  That's what RFC 4861 is doing.  Acting as that "other document" that introduces a useful application of ICMPv6.


          To recap, RFC 4443 defines ICMPv6.  RFC 4861 describes how ICMPv6 is leveraged to perform neighbor discovery.

          • 2. Re: ICMPv6 vs ICMPv6 ND


            can we say that ICMPv6 is huge point and under it sub-point called ICMPv6 ND?

            i will draw to you what make me confused:-


            is that what you mean? is that what you need to explain? or iam wrong ?

            • 3. Re: ICMPv6 vs ICMPv6 ND
              Steven Davidson

              Right.  ICMPv6 is the straw that stirs the drink.  Several IPv6 features are made possible by ICMPv6.   All you need to do to add a new feature is to add another message type.

              • 4. Re: ICMPv6 vs ICMPv6 ND


                i want to asking you another question i think it`s  very easy  or stupid

                what is the difference between the word "digit " and "Number" in English language ?

                i networking  field is there any difference  ?

                • 5. Re: ICMPv6 vs ICMPv6 ND
                  Steven Davidson

                  46 is a number.  4 and 6 are the two digits which make up the number 46.   I don't think there is any kind of special designation in networking.

                  • 6. Re: ICMPv6 vs ICMPv6 ND

                    Dear Mohamed--I'm not going to write much about your original question, except to say that Steven answered it quite clearly, I think.  (And also, I know that Steven "enjoys" reading the RFCs more than anyone else I know!)


                    I might have written this to you or someone else a while back.... the RFCs are written in a very formal English style that is much more typically used in the legal profession when writing to the court.  As a retired lawyer, and native English speaker, I can tell you that even I have some trouble understanding them sometimes! So hang in there, and don't give up!


                    If something is described as an "industry standard" (versus something that is "proprietary") then it means that it has been submitted to some reviewing body (in the case of RFCs it's the IETF).  The reviewing body has approved the technology and published a description of the technology.  (In this case, the RFCs are the IETF's description of technology it has approved of.)  That means, if there is ever a question on how a standard technology works, the published standard describing it is the best source of information.


                    But as we both found out, however, they might not be the easiest things in the world to read!  So, the next step is what you are doing... consulting other sources such as textbooks, white papers, and our peers! 



                    • 7. Re: ICMPv6 vs ICMPv6 ND


                      ok now i understand

                      but what is the difference between "digit" and "decimal"and "binary"?

                      ok i will draw you what make me confused :-

                      we have 3 types of counting systems:-

                      1-hexa-decimal counting system (hexa-decimal  digit)

                      2- binary counting system

                      can we say about this counting system is "binary  digit " ? or "binary number"

                      in other words ,  why we don`t say "binary digit" like we say "hexa decimal digit" ? why we remove keyword "digit "after"binary"?

                      3- decimal counting system

                      same thing , can we say "decimal digit" like what we do in "hexa-decimal digit" ? or we must say "decimal" without keyword "digit" ?

                      does "digit"keyword in "hexa-decimal digit" only added beside "hexa-decimal" ? or we can add it beside "binary"and "decimal"

                      iam sorry for this long question, but i need to let you understand question inside my brain

                      sorry again

                      • 8. Re: ICMPv6 vs ICMPv6 ND
                        Steven Davidson

                        According to merriam-webster.com a digit is not limited to decimal.  It can apply to binary (base 2), and hexadecimal (base 16).   I don't know why we say hexadecimal.  I just say hex.  So basically there are eight binary digits in decimal number 255 (which has three digits).  255 is also FF (a two digit hexadecimal value).

                        • 9. Re: ICMPv6 vs ICMPv6 ND

                          Hexadecimal-- hexa is Greek (I think?) for six and deci is ten.  So hexadecimal means 6 + 10.  16.  Hex for short. 


                          A digit is the sub-unit that makes up a number.  So in the different counting systems:

                          • 27 is the number.  2 and 7 are the digits.  (Decimal digits are 0-9.)
                          • 11011 is the number.  0 and 1 are the digits.  (Binary digits are 0 and 1.)
                          • 1B is the number.  1 and B are the digits.  (Hexadecimal digits are 0-9 and A-F.) 


                          why we don`t say "binary digit" like we say "hexa decimal digit" ? why we remove keyword "digit "after"binary"?



                          We don't use the keyword digit after the word describing the counting system because referring to the digit means we are talking about the sub-units not the whole number, we rarely talk about the digits themselves.  Generally what is important is not the individual digits, but the value of the number that the digits make up.  However, if you were having a discussion about the digits, it would be correct (and probably more clear) to use the word digit.  If you were having a discussion about the difference of digits among the various counting systems, you would use both words.... binary digits are cooler than hexadecimal digits, for example.


                          On the other hand, we will often talk about the "binary number" or the "hex number" or the sometimes, "the number".  Here we refer to the value of the whole unit.  In the example I gave above, all of the numbers I gave represent the same value.  So if we were having a conversation about at number, and the counting system didn't matter, it would be OK to refer to it as "the number."  But if it were important to make the distinction between the counting systems, it would be correct and more clear to say, "the binary number... the hex number... the decimal number."  (Or better, "the number in ... [counting system]".)


                          Does this make better sense?  MM