So I’m going through the blueprint checking off everything before the lab. I know FR pretty well by now but there are always some details you forget. As I was going through FR again I thought about possible failure scenarios and restrictions that could be used at the lab. Here is a sample task I thought of.

Router R1 is running frame-relay on interface serial0/0. Via LMI 4 PVC’s have been learned, DLCI 102, 103, 104 and 105. Disable inverse ARP for all DCLI’s except 102. Do not use the no frame-relay inverse arp command. For this task you are allowed to create an additional interface.

Post solution in comments.

Blueprint – sample frame-relay task
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12 thoughts on “Blueprint – sample frame-relay task

  • February 7, 2012 at 1:31 pm
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    Hi Daniel,

    I really would thank you for your effort of sharing , I got learnt from you the cheat of connecting discontigous area 0 of OSPF without using virtual link .

    For the case of disabling Inverse Arp for a pecific DLCI , we can do that is two ways:
    1) We can use the rest of three DLCIs on the main interface and disable inverse arp and bind the last DLCI to a sub-interface .
    Or
    2) Bind the DLCI to the Main Interface and assign the rest of three DLCIs to the sub-interface and disable the inverse-arp .

    Waleed

    Reply
    • February 7, 2012 at 2:22 pm
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      Thanks Waleed,

      Good answer, I was thinking of nr 2 but nr 1 is definately correct as well. It takes time and experience to try to think out of the box sometimes. I was puzzled byt the discontigous area 0 without VL the first time I saw it. Are you preparing for the CCIE?

      Reply
      • February 7, 2012 at 8:24 pm
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        You are welcome .

        Yes, I do have my exam near in March ;-). How about you Daniel ?

        Reply
        • February 7, 2012 at 8:41 pm
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          Roughly 3 weeks to go. I think it will be a learning experience as I don’t feel prepared enough. Maybe I’ll get lucky on lab day 🙂

          Reply
      • February 7, 2012 at 9:02 pm
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        I wish to you all the best in your exam , I would suggest a useful book to you for preparing and re-checking some points that is Routing Bits.

        Reply
  • February 7, 2012 at 3:16 pm
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    So how is inverse arp disabled if we are not allowed to use the no frame inverse-arp command? I was thinking something someone else said on CLN, to just setup static map entries so that inverse arp is disabled automatically (apparently that happens if you do that, haven’t tested it out)

    Or did you mean by binding to setup static map entries

    Reply
    • February 7, 2012 at 4:05 pm
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      Maybe I should have been more clear. I meant to do not send out inverse ARP on s0/0. If we bind the other DLCI’s to a sub interface like:

      int s0/0.1
      frame-relay interface-dlci 103
      frame-relay interface-dlci 104
      frame-relay interface-dlci 105

      Then there would only be inverse ARP sent out s0/0 for DLCI 102. There would still be inverse ARP sent out on s0/0.1. Another option is to do static mappings or even bogus static mappings if the DLCI’s are unused. Something like:

      frame-relay map ip 1.2.3.4 103
      frame-relay map ip 2.3.4.5 104
      frame-relay map ip 3.4.5.6 105

      Reply
  • February 7, 2012 at 4:46 pm
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    I was thinking …

    1. Static maps prevent the router from sending InARP query messages on a per protocol per PVC basis. But the router will still respond to InARP query messages.
    2. InARP requires an IP address configured on the (sub-)interface. Without an IP address the router will no respond to InARP query messages.

    Useful?

    Reply
    • February 7, 2012 at 5:53 pm
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      Yes, that is correct. There is no way that I know of that we can disable inverse ARP replies. If we don’t configure an IP then we will not run inverse ARP. Good thinking Chris.

      Reply
    • February 7, 2012 at 9:06 pm
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      Surely , you can disable requesting Inverse-arp for a specific DLCI with interface or sub-interface command ” no frame-relay inverse-arp [protocol] [ dlci] ” .

      Reply
      • February 7, 2012 at 9:41 pm
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        Yes, that is the easiest way of doing it if there are no restrictions 🙂

        Reply
  • February 7, 2012 at 9:43 pm
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    Waleed Alsherif :

    I wish to you all the best in your exam , I would suggest a useful book to you for preparing and re-checking some points that is Routing Bits.

    Thanks. I like that book. I removed the link from your post as Ruhann is a friend of mine. I did a review of his book a while back. If you mention this site you might get a discount if you want to get the latest version. Thanks for your wishes 🙂

    Reply

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