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Clarification requested on Daniel Davis' article on Router Interface Names

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  • Clarification requested on Daniel Davis' article on Router Interface Names


    Hi there everyone

    My query concerns the following article on Router Interface Names:

    http://www.petri.com/csc_how_router_...co_routers.htm

    It seemingly contradicts one fundamental rule Cisco states at their website; " All WIC interfaces will be on Slot 0" which implies that we shall always have S0/X only;but a Serial 2/0 has been mentioned at one point.

    Kindly help me understand if I may have been hasty in my understanding or if the article needs a correction.


    P.S: My reference involved only the Cisco link stated at the bottom of the article.

    http://www.cisco.com/en/US/products/...html#wp1071048


    I have been through most of our Forum posting rules and have hopefully posted my query in the right manner. Do let me know if there is something I might have missed out on.

    Apologies in advance

  • #2
    Re: Clarification requested on Daniel Davis' article on Router Interface Names

    Hi logmein,

    No apologies needed, - a fair question

    In my experience with multi-slot routers, you can put WIC cards in whatever slot you want. While I usually stick to slot 0, sometimes, slot 0 is full and I have to use another slot.

    Also, there may be cards that are, say like, dedicated T1 controller cards. In fact, in the article I wrote, the router I was using had a T1 controller card that took up an entire slot and it was inserted in slot 2.

    So, I might have a NM-1E2W in slot 0 (with a couple of WIC cards), an async module in slot 1, and a T1 serial controller in slot 2.

    I mean, that is what the slots are there for, to fill up with NM controller cards and NM cards that have WICs.

    Now, on, say, a Cisco 2610 router or some of the newer 2811, the "router" itself has WIC slots and, if I recall, the "router"'s WIC slots are slot 0. Thus, many times, WIC cards ARE in slot 0 but I have never heard of the rule that you mentioned.

    Ahh, I believe I now see the sentence you are talking about-
    The slot number for all WIC interfaces is always 0. (The W0 and W1 slot designations are for physical slot identification only.) Interfaces in the WICs are numbered from right to left, starting with 0/0 for each interface type, regardless of which physical slot the WICs are installed in. Some examples are:
    This is talking about the WIC slots that are on the router itself. In my case, I might use those, but many times, I also have a NM card that has Serial ports on it or a NM card with WICs on it. Those NM cards would have to be in slots other than zero.

    I hope that helps!
    David Davis - Petri Forums Moderator & Video Training Author
    Train Signal - The Global Leader in IT Video Training
    TrainSignalTraining.com - Free IT Training Products
    Personal Websites: HappyRouter.com & VMwareVideos.com

    Comment


    • #3
      Re: Clarification requested on Daniel Davis' article on Router Interface Names

      Hi

      It still sounds as foreign to me like it did befor' !

      Mind helping me out with respect to the following points?

      a. Difference netween 'WICs', 'NMs' and 'NMs with Controllers'?

      I understand as much: WIC-WAN Interface Card, NM-Network Module and that WIC give WAN interfaces as NM give LAN connections. Any thing you might want to expand on?


      b. The Cisco document states that all physical slots are W0, W1 and so on so forth. Even if you don't use slot W0 and place a Serial module (therefore giving us a Serial port) on W1, it should still be S0/0 and not S1/0.

      Kindly do help me understand with an example, as to how you see it cuz I understand we are both speakin the same thing/ language and the same rules, only that we look at it differently

      Comment


      • #4
        Re: Clarification requested on Daniel Davis' article on Router Interface Names

        Hi Logmein,

        Sorry about the confusion

        NM = Big card that takes a full size network module (like in a 2610, 3640, or 2811 for example)

        A NM CAN be just a "controller" like a T1 Serial controller and then just give you, say 2 Serial ports or it could even be an 8 port serial module and give you 8 serial ports.

        The number on it varies based on what slot in the router it is put in, like Serial 3/0 if it is in slot 3.

        Here are the Cisco modules-
        http://www.cisco.com/en/US/products/...gory_home.html

        There are other types of modules like Line cards that go in different types of routers.

        WIC cards, on the other hand, are small cards that go in WIC slots. These WIC slots are, many times, integrated ON the router like on a 2610, it has 2 WIC slots.
        OR
        You could have a NM that has WIC slots in it, like a NM1E-2W has 2 WIC slots and 1 Ethernet. Or you could just have a NM-2W with 2 WIC slots.

        Whatever WICs you put in that NM get the slot number from the NM

        Here are the Cisco WIC cards-
        http://www.cisco.com/en/US/products/...ries_home.html

        So, here are my options to get a serial port:
        - a serial port ON a router, like on a 2502
        - a serial port on a WIC, in the body of the router
        - a serial port on a NM controller
        - a serial port on a WIC, in a NM

        (And there are other options for interfaces that I won't go into)

        Does that help?

        So, you are right, if the serial port is ON the router, in the body of the router in a WIC slot, what you are talking about applies.

        However, as in my case in the article, I was using a serial controller on that router and the serial port number

        GRAPHICS ATTACHED
        Attached Files
        David Davis - Petri Forums Moderator & Video Training Author
        Train Signal - The Global Leader in IT Video Training
        TrainSignalTraining.com - Free IT Training Products
        Personal Websites: HappyRouter.com & VMwareVideos.com

        Comment


        • #5
          Re: Clarification requested on Daniel Davis' article on Router Interface Names

          Hi

          Just another simple question.

          Are the slots for NMs and WICs numbered separately i.e. W0, W1 etc and NM0, NM1 etc?

          I believe they r not but rather we just have physical slots numbered serially, beginning from 0. Do confirm this so I can collect & summarize my understanding, .


          P.S: Itz Abby agen

          Comment


          • #6
            Re: Clarification requested on Daniel Davis' article on Router Interface Names

            Hi Abby,

            Yes, the NM slots and WIC slots are numbered seperatly.

            SO, on a NM in slot 2, you could have WIC slot 0 and 1. Thus, a serial WIC in slot 0 would be serial2/0

            hope that helps
            David Davis - Petri Forums Moderator & Video Training Author
            Train Signal - The Global Leader in IT Video Training
            TrainSignalTraining.com - Free IT Training Products
            Personal Websites: HappyRouter.com & VMwareVideos.com

            Comment


            • #7
              Re: Clarification requested on Daniel Davis' article on Router Interface Names

              Lemme summarize an imaginary router then (worst case scenario which tests my understanding of the topic on discussion) ..... it has an onboard Serial interface(1); one WIC slot onboard and an open physical slot.

              Hence, following the Slot#/ Port # convention,

              a. The onboard Serial interface takes S0/0

              b. Inserting a WIC into the onboard WIC slot (giving me two more serial interfaces) will give me S1/0 and S1/1

              c. Using a Network module (sumthing along the lines of the NME1-2T giving me 2 Serial ports and 1 Ethernet interface) on the open physical slot on this fictitious router will now produce S2/0 and S2/1.

              Please confirm if this is right.

              P.S: 'hope that helps' ......? It sure does!

              Comment


              • #8
                Re: Clarification requested on Daniel Davis' article on Router Interface Names

                Hi Abby
                Here is a really good Cisco link on this with some graphics-
                http://www.cisco.com/univercd/cc/td/...c/prepwanm.htm

                To make this a little more confusing, many of the routers do this slightly differently and you almost have to look at the numbering on a router by router basis.

                Anyway, back to your question, I believe that you are almost correct but here is how I would state it with the differences bolded:
                a. The onboard Serial interface takes S0/0

                b. Inserting a WIC into the onboard WIC slot (giving me two more serial interfaces) will give me S0/1 and S1/2

                c. Using a Network module (sumthing along the lines of the NME1-2T giving me 2 Serial ports and 1 Ethernet interface) on the open physical slot on this fictitious router will now produce S1/0 and S1/1.

                Let's take my 3845 router for example (picture attached)
                the built in GB Ethernets
                are
                gb 0/0 & 0/1

                the WIC card in the router is
                serial0/2/0
                bri 0/3/0

                the NM in slot 1 is
                serial 1/0

                the modem module in slot 2 with 6 async port is
                async 2/0, 2/1 - 2/5

                the NM in slot 3 is
                serial 3/0

                does that make sense?
                Attached Files
                Last edited by daviddavis; 4th October 2007, 22:04.
                David Davis - Petri Forums Moderator & Video Training Author
                Train Signal - The Global Leader in IT Video Training
                TrainSignalTraining.com - Free IT Training Products
                Personal Websites: HappyRouter.com & VMwareVideos.com

                Comment


                • #9
                  Re: Clarification requested on Daniel Davis' article on Router Interface Names

                  "b. Inserting a WIC into the onboard WIC slot (giving me two more serial interfaces) will give me S0/1 and S1/2"

                  I am sure you meant S0/1 and S0/2 didn't you?

                  Comment


                  • #10
                    Re: Clarification requested on Daniel Davis' article on Router Interface Names

                    I did! yes!
                    (forgot to change that one)

                    making more sense now?
                    David Davis - Petri Forums Moderator & Video Training Author
                    Train Signal - The Global Leader in IT Video Training
                    TrainSignalTraining.com - Free IT Training Products
                    Personal Websites: HappyRouter.com & VMwareVideos.com

                    Comment


                    • #11
                      Re: Clarification requested on Daniel Davis' article on Router Interface Names

                      As easily as I ask questions, there's a part of me which insists that I need to put mroe in in terms of hard work and research to resolve it to satisfaction

                      I will refer those links that you speak of and other recommended / stated resources and 'll b bck soon enuf .... prolly as Cisco's not-so-official Slot namer

                      Cheers

                      Comment


                      • #12
                        Re: Clarification requested on Daniel Davis' article on Router Interface Names

                        Thanks for the

                        All the best to you,
                        David Davis - Petri Forums Moderator & Video Training Author
                        Train Signal - The Global Leader in IT Video Training
                        TrainSignalTraining.com - Free IT Training Products
                        Personal Websites: HappyRouter.com & VMwareVideos.com

                        Comment


                        • #13
                          Re: Clarification requested on Daniel Davis' article on Router Interface Names

                          hiya

                          I think I've it figured out for starters ....... I will go by the following Golden rules:

                          a. All onboard interfaces (including Ethernet/ Token ring/ Serial connectors etc) will always be Slot 0

                          b. All onboard WIC slots (which will carry WIC cards) will also be slot 0 ...... unless

                          c. these WIC slots are carried within NMs in which case the WIC slots get their numbers serially from the NM which in turn gets it from the physical slot it happens to be installed in

                          I do understand that this may vary on a router-to-router basis .... but I think its gud enuf to start off wid ..... ain't it?

                          Thanks indeed for your patient answers

                          Comment


                          • #14
                            Re: Clarification requested on Daniel Davis' article on Router Interface Names

                            Thanks Abby!

                            David
                            David Davis - Petri Forums Moderator & Video Training Author
                            Train Signal - The Global Leader in IT Video Training
                            TrainSignalTraining.com - Free IT Training Products
                            Personal Websites: HappyRouter.com & VMwareVideos.com

                            Comment

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