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

ptlinva

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,
Paul

shodown

Loopbacks on the router or the management VLAN on a switch. No need to use a punch of machines.

ptlinva

I'll give it a try and post my results..

Thanks for your time replying!

Your friend,
Paul

johnwest43

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.

d6bmg

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.

powmia

"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 Rodriguez

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.

edj1963

...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.
I have a lab set up and plenty of hardware to use but missing something fundamental.

Thanks.

networker050184

So for example 10.0.0.0/24 is your end host network on one side and 10.1.0.0/24 is on the other. Just create a loopback with an IP in that range and you can test connectivity that way.

R1
interface loopback10
ip address 10.0.0.1 255.255.255.0

R2
interface loopback 10
ip address 10.1.0.1 255.255.255.0

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

ping 10.1.0.1 source 10.0.0.1

edj1963

@ 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!

Respectfully,

Ed