RIPv2 Broadcast Updates

Task

  • Configure R1 and R6 so that RIPv2 updates sent over VLAN 146 use broadcasts instead of multicasts.

 

Just to point out that an alternate configuration can be using the neighbor statement with the segment broadcast address and also putting in passive mode the interface.

 

router rip

passive-interface FastEthernet0/1.146 (My rack has no GigE interfaces)

neighbor 155.1.146.255

R6: Debug ip rip events and debug ip packet (I created and acl for this)

RIP: received v2 update from 155.1.146.1 on FastEthernet0/1.146

IP: tableid=0, s=155.1.146.1 (FastEthernet0/1.146), d=155.1.146.255 (FastEthernet0/1.146), routed via RIB
IP: s=155.1.146.1 (FastEthernet0/1.146), d=155.1.146.255 (FastEthernet0/1.146), len 472, rcvd 3

Comments

  • JoeMJoeM ✭✭✭

    Task


    • Configure R1 and R6 so that RIPv2 updates sent over VLAN 146 use broadcasts instead of multicasts.


    Just to point out that an alternate configuration can be using the neighbor statement with the segment broadcast address and also putting in passive mode the interface.

    Hi c1sc0m,

    This is an interesting router trick.  I did a quick mini-lab to play with the idea -  a little warmup for more CCIE labbing ;-).  

    Unfortunately, I don't think your alternative method fulfulls the intent of the requirement.

    1. A requirement like this is testing your knowledge of a specific command with RIP. Easy points.
    2. Technically, your command produces a subnet "broadcast". But with the correct RIPv2 command, the broadcast looks like this   255.255.255.255    vs like this   X.X.X.255
    3. The alternative makes it necessary to remove any other network/neighbor commands pointing to that interface -- otherwise both unicast and multicast advertisements would be sent out the interface.  debug shows this

     

    I say extra-points for creativity and looking for options to solve a task, but minus points for not using the expected command.

    No RIP on the v5 lab blueprint, right?   But still something to think about as far as getting quick and easy points.   Tick-Tock goes the clock in the lab. ;-)

     

  • Hi JoeM,

     

    Oh I totally agree with you, and thanks for your comments.  I really appreciate it.

    This was a thing just came to mind to try and it worked like a charm.

    Anyways, if they ask a way to do this without the ripv2 broadcast feature under the interface config mode, now we know this other way.  [8-|]

  • Don't worry man.  Technically we can say it's a unicast sent to VLAN146's broadcast address.  We all agree that the first thing comes to our minds when reading "broadcast" is 255.255.255.255.

    What I did let's say was a directed broadcast message.

  • JoeMJoeM ✭✭✭

    RIP was removed from the Cisco Lab Blueprint.  But for correct lab-exam thinking, we need to always think about how a requirement will be verified by the Cisco people.

    Maybe someone can give some input on this part.  How would Cisco check to see that we implemented it correctly?

    For my mini-lab test of this, I was able to see I had a subnet broadcast AND a unicast message -- because I was advertising that network.     

    Maybe Cisco would just do a command verification.   This is the thing we always have to think about.  I remember Peety always drilling this in with his posts about preparing for a lab.   How would it be verified by Cisco? What are they looking for with the theasarus synonyms in each question.   INE does a good job with producing questions like this (you either know or you don't).  That is the take-way, I think......but still extra points for creativity. ;-)

  • RIP was removed from the Cisco Lab Blueprint. 
    RIP was removed from the Cisco Lab Blueprint.

    Sure? I thought it was v1 not v2 as well.  On my 1st attempt I really can't recall if there was RIP redistribution.  Anyways is always good to review everything.

    Btw I hope to retake on July this year (I already scheduled).  Right now I'm doing v5 again to review concepts, the will continue with Narbiks and probably 360. Not sure which of the 2 will be better.  Prior my 1st attempt I did WB1 - 3 and some TS labs, but honestly didn't practice as I should.  Now I'm focusing

    on details. But how 'bout you bro?

     

  • JoeMJoeM ✭✭✭

    Thanks for correcting me on this.  I thought that it was just on the written.  

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