why dont vlans show up on switch when i make them.

[dolanduck.]

studying for CCNA

i have two questions  

when i make vlans say vlan 2,3 then exit why don't they show up in my running config or show ip interface brief.

 and for the second question when i use show ip interface brief and it show that a vlan is status up  and protocol down what does that mean? 

[Manoj Papisetty · Accepted solution]

Creating VLANs and creating SVIs (Interface VLANs) are two different things.
If you are creating a VLAN on the switch, you are not creating any interfaces. So it wont show up in the "show ip int br". And when you create an interface vlan, it will show up in the "sh ip int br" but the protocol will remain down until there is atleast a single data interface that can forward this vlan. Quick check is to see spanning tree for that vlan.

In summary, for an SVI -
1. Create vlan
2. Assign the vlan to any interface and bring it up
3. Create SVI and check the status, it should be up/up now.

[dolanduck.]

well i made vlan 20 and did int vlan 20 its in up down

then i assigned my  interface f0/14 to vlan 20 but it still shows as up down 

[Manoj Papisetty]

Is the interface up and forwarding this vlan?
Only when f0/14 is up and can forward this vlan traffic, your svi will be up. Otherwise, can you share the output for "show int vlan 20"?

[dolanduck.]

oh wait do i need a device connected to that port ?

[Manoj Papisetty · Accepted solution]

yes. There must be atleast a single interface up and able to forward traffic on the vlan. Only then the interface vlan will come up.

[Martin L]

Or add "switchport autostate exclude" < interface level command to stop SVI to checking/monitoring traffic on access port(s) that belong to vlan x

[Martin L]

you do not see any vlans with Show vlan or show vlan brief ?
to store vlans in running config switch vtp must be in vtp transparent mode and not vtp server/client which  stores vlan and vtp info in vlan.dat file on flash.
if you see vlans with sho vlan but your Interface vlan X is down is due to auto-check if any host is up on that vlan x. in other words, there must be access vlan x assigned to port and such port must be Up. there is option to exclude such check with switchport interface mode command (don't remember exact command)

Update: "switchport autostate exclude" is  command to stop SVI to monitor status of access port

Regards, ML
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[dolanduck.]

No i was trying to figure out why my the Vlans i created were not showing up on my running config and show ip interface brief command and i was experimenting on my switch.