Use of loopback or ethernet ports for testing in home lab...

ptlinvaptlinva Diggin' 4 Cisco GoldMember Posts: 125
After moving, I've set back up my home lab in order to study for my CCNP switch test.

I used to use multiple computers plugged into ports on various switches/routers for my end-to-end ping test.

However, due to power, I'm having to come up with other ways of performing end-to-end test. I've started setting up loopbacks but remember something from my ccna days about turning on an ethernet port (even though nothing was plugged into it) so that it appears to be in an up/up state.

What do you use to simulate end-point devices? Any secrets you care to share?

Thank you so very kindly for your time and suggestions.

Your friend,


  • shodownshodown Senior Member Member Posts: 2,271
    Loopbacks on the router or the management VLAN on a switch. No need to use a punch of machines.
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    CUCM SRND 9x/10, UCCX SRND 10x, QOS SRND, SIP Trunking Guide, anything contact center related
  • ptlinvaptlinva Diggin' 4 Cisco Gold Member Posts: 125
    I'll give it a try and post my results..

    Thanks for your time replying!

    Your friend,
  • johnwest43johnwest43 I'd rather be fly fishing Member Posts: 294
    For turning on an ethernet port that is not cabled use the command "no keepalive", however as shodown already said loopbacks are the best for this.
    CCNP: ROUTE B][COLOR=#ff0000]x[/COLOR][/B , SWITCH B][COLOR=#ff0000]x[/COLOR][/B, TSHOOT [X ] Completed on 2/18/2014
  • d6bmgd6bmg BMG FTW!! Member Posts: 241
    Loopsbacks serve the purpose of end machine.
    Personally, I use loopbacks, 'no keepalive', VPCS for basic connectivity and virtual hosts of vmware & virtualbox.
    The choice dependent on what I plan to do with the host.
    [ ]CCDA; [ ] CCNA Security
  • powmiapowmia Senior Member Users Awaiting Email Confirmation Posts: 322
    "no keepalive" is for physical ports, but doesn't work on all switches. "no autostate" is for a vlan interface, and also does not work on all switches. Either use loopbacks or have an active trunk on your switch that has your vlans allowed. For example, if you have something plugged into a port that is configures as "switchport access vlan 10", just force the port to trunk (sw mode trunk) with 10 as the native vlan. That way the host connected to that port will see no difference, but you will have a port that is active in all of your vlans... so your vlan interfaces will all be up.
  • Bender RodriguezBender Rodriguez Junior Member Member Posts: 12 ■□□□□□□□□□
    Loopbacks are the way to go. It is what I personally use in my home lab. Also, one command I have found very useful is the extended ping command. You can source your pings from specific addresses/interfaces to simulate a ping from 1 subnet to another.
  • edj1963edj1963 Junior Member Registered Users Posts: 2 ■□□□□□□□□□
    ...with something I should understand, but I am not getting this.

    I take from this thread, I should be able to emulate hosts (for end-to-end) using a switch or an loopback address on a router.....I'm apparently slow on the uptake. Would someone be gracious enough to help me configure this? I understand loop back and vlan but I can't get my brain to get it as it applies here or how to set it up. icon_redface.gif
    I have a lab set up and plenty of hardware to use but missing something fundamental.

  • networker050184networker050184 Went to the dark side.... Mod Posts: 11,962 Mod
    So for example is your end host network on one side and is on the other. Just create a loopback with an IP in that range and you can test connectivity that way.

    interface loopback10
    ip address

    interface loopback 10
    ip address

    Now you can just ping sourcing these interface addresses to test end to end connectivity.

    ping source
    An expert is a man who has made all the mistakes which can be made.
  • edj1963edj1963 Junior Member Registered Users Posts: 2 ■□□□□□□□□□
    @ networker050184,

    Wow, thank you. Seeing it stated like you did makes perfect sense, I was WAY over complicating the issue needlessly. Simple and elegant....I really have to stop over thinking things, it's a damnable character trait.

    The only other question I have about this; Can I do this with sub-interfaces as well?

    Thanks very much for the light, I appreciate it!


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