up'ing an interface

DevilWAH

I am playing around with my lab and have a number of Vlan interfaces on a switch I want to force up.

my only problem is that the vlans don't have any connected physical interfaces and are not allowed on any of the trunk links. So the vlan/interfaces are down...

I thought you could force a physical port up with out any thing connected but either I have forgotten how to, or you can't do it.

You guys got any way to do it ?

here is what I see at the moment

Interface IP-Address OK? Method Status Protocol
Vlan100 yyy.xxx.112.62 YES manual up down
Vlan200 192.168.112.62 YES manual up down

Cheers

Forsaken_GA

if I remember right, it all depends on the switch. On some you can diable autostate, others you have to disable keepalives, and there's a third method which escapes me at the moment

DevilWAH

LOL I think its that third one that I need

jason_lunde

have you tried
no keepalive
?

mikej412

In config mode you can set the state active

vlan 20
state active

DevilWAH

nope nope and nope LOL

if I allow the Vlans on the trunks then they come up fine.

I found one way to do this for testing is to allow the vlans on the trunk at the access/distribution layer, but block them at the core layer (the idea is these are local VLANS so should not be trunked back to the core)

This is not ideal so if any one can think of any other way to force physical port up I would be greatfull,

3750's don't have the autostate command, and a "no keep alive" does not bring up the port. Also the "state active" only seems to tell the vlan if it can become active or not, it does not force the issue.

Cheers for the ideas though guys.

Forsaken_GA

honestly, the easiest way I found to get away with this was to take an unused port, put it in the vlan, and then put a loopback plug into the port. That got the port up, the vlan interface up, and didn't have any effect on the live network

That, or setup a second trunk and allow only those vlans on it

ColbyG

Why do you need to force them up?

DevilWAH

i think the loopback plug the way to go. just not at work so thinking of a way to do it remotly. as for why i want to force it up. i am mocking up some thing for work that requires both local and end to end vlans. the local vlans wont come up because they arnt trunked, and don't have any active ports. but if the vlan does not come up the vlan int ip does not get added in to routing protocols. i know i can get around this other way, but as this it to show to managment i want it as close to real life as poss.

notgoing2fail

I tried to do this myself, but how do you add a loopback interface to a vlan?

DevilWAH

under the vlan interface you can enter the command

#loopback

but I don't know what it does, it don't bring the interface up and I didn't bother looking it up. (or i could not find much about it)

Forsaken is talking about making a physical loopback rj45 plug, (wireing the TX and RX wire togather, so 1 to 3 and 2 to 6 with in the same RJ45 plug http://spacehopper.org/5-in-1/images/loopback.jpeg )

this will bring up a physical port on the device, so you can place that in the vlan and the vlan will come up.

networker050184

Try no autostate under the SVI. Its a hidden command I believe so help won't show it.

DevilWAH

networker050184 wrote: »

Try no autostate under the SVI. Its a hidden command I believe so help won't show it.

nope just give a invalid input detected.

maybe its cause I have an older IOS versions 12.2(22).. i might upgrade tomorrow and see if it helps

notgoing2fail

DevilWAH wrote: »

under the vlan interface you can enter the command

#loopback

but I don't know what it does, it don't bring the interface up and I didn't bother looking it up. (or i could not find much about it)

Forsaken is talking about making a physical loopback rj45 plug, (wireing the TX and RX wire togather, so 1 to 3 and 2 to 6 with in the same RJ45 plug http://spacehopper.org/5-in-1/images/loopback.jpeg )

this will bring up a physical port on the device, so you can place that in the vlan and the vlan will come up.

Oh I see....

So I suppose short of a loopbacked cable, is there really no way to accomplish what you're looking to do?

Your question doesn't sound like anything anyone else had never asked?


I can see why you would want the SVI to be up for management purposes, there has to be a way!!??

Forsaken_GA

DevilWAH wrote: »

i think the loopback plug the way to go. just not at work so thinking of a way to do it remotly. as for why i want to force it up. i am mocking up some thing for work that requires both local and end to end vlans. the local vlans wont come up because they arnt trunked, and don't have any active ports. but if the vlan does not come up the vlan int ip does not get added in to routing protocols. i know i can get around this other way, but as this it to show to managment i want it as close to real life as poss.

If all you're trying to do is get the subnet into a routing protocol for some sort of proof of concept, why not just use a loopback interface? If you're not doing something that specifically requires an SVI, the loopback will get the route into the routing table and you can move on from there

notgoing2fail

networker050184 wrote: »

Try no autostate under the SVI. Its a hidden command I believe so help won't show it.

He's right!!! And this works!!!

I just tried it on my 1811 and my VLAN 2 with no hosts attached suddenly went up!

I can successfully ping the SVI.

Unfortunately, I believe this command is only valid for routers and not switches.

I'll jump on my 3550 later to see if it works....I'll also try it on my 2960...

DevilWAH

Your right only on routers..... switches it does not work

Just check the docs and thats what it says ..

DevilWAH

Forsaken_GA wrote: »

If all you're trying to do is get the subnet into a routing protocol for some sort of proof of concept, why not just use a loopback interface? If you're not doing something that specifically requires an SVI, the loopback will get the route into the routing table and you can move on from there

Oh thats what I have done, This is jsut for presenting to managers and other non networking staff. It would be nice to have the digrams/configs on the table as an exact copy of it on the test system to demo. Rather than trying to explain.. "Yes i know its a vlan on the digram but I am just using loopbacks for testing.... etc... " and them getting all confused.

I was just thinking if there was a 2 second command to bring up the vlan it would be great. As there's not its just going to be I will just make up a few loopback rj45's, so I can keep the final config for them to see working.

It seems loopback rj45 plugs (even with all 8 pins connected) dont work on 3750G switchs, in the end jsut used a standard cross over between two unused ports and set it as a trunk. So it seems you can loopback between two seperate interfaces but not to a single one.

Rhoshambo

Configure an unused switchport interface as a trunk port and no keepalive on that interface. Pretty simple

QHalo

I wonder if he's still trying to figure out this issue....after two years.

networker050184

DevilWAH wrote: »

3750's don't have the autostate command, and a "no keep alive" does not bring up the port. Also the "state active" only seems to tell the vlan if it can become active or not, it does not force the issue.

If you're going to dig up a two year old thread at least read it thoroughly!