I am sure this is a dumb question

colink24colink24 Member Posts: 43 ■■□□□□□□□□
But please can someone put me out of my misery and answer it?! I know this is a simple answer but I am having something of a brainfreeze and its bugging me

I am watching the nuggets for BSCI and will be building a lab shortly to go through the lab portfolio. In the nuggets, Jeremy creates sub interfaces on his serial connections. What I dont understand is how these connect up physically!

So assuming I have R1 as my backbone router, connecting to R2 and R3. I notice Jeremy has a serial interface that is up but he creates sub interfaces, which is fine. What I dont understand is how 1 physical interface can be connected to R2 and R3?? I get the fact these are sub interfaces but I still need to be able to connect to both routers? It would make more sense to me if he has 2 serial interfaces, and created sub interfaces for those

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Comments

  • DPGDPG Member Posts: 780 ■■■■■□□□□□
    Was there a frame relay switch between the routers?

  • colink24colink24 Member Posts: 43 ■■□□□□□□□□
    DPG wrote: »
    Was there a frame relay switch between the routers?

    I considered this but he doesnt show it in his topology
  • DPGDPG Member Posts: 780 ■■■■■□□□□□
    Which video in particular?

  • networker050184networker050184 Mod Posts: 11,962 Mod
    Most likely frame relay as DPG pointed out.
    An expert is a man who has made all the mistakes which can be made.
  • ColbyGColbyG Member Posts: 1,264
    That's how FR works, they're virtual connections via DLCIs.
  • mikej412mikej412 Member Posts: 10,086 ■■■■■■■■■■
    colink24 wrote: »
    I considered this but he doesnt show it in his topology
    Is the topology a cloud with DLCIs at the ends of the connections?

    Is there any frame relay as part of the configuration?
    :mike: Cisco Certifications -- Collect the Entire Set!
  • billscott92787billscott92787 Member Posts: 933
    Chances are like everyone else said it is a frame-relay cloud/topology that is using sub-interfaces.
  • colink24colink24 Member Posts: 43 ■■□□□□□□□□
    mikej412 wrote: »
    Is the topology a cloud with DLCIs at the ends of the connections?

    Is there any frame relay as part of the configuration?

    The topology shows no cloud, and the show commands he uses do not show the frame relay config (if it exists). His topology just shows the routers connected back to back via serial links, yet his config is on sub interfaces

    I think its best to assume its frame relay, but boy its annoying he doesnt take you through his lab setup prior to the vids!
  • colink24colink24 Member Posts: 43 ■■□□□□□□□□
    DPG wrote: »
    Which video in particular?

    Router redistribution, I think video 16 or 17 in the series
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