vlan svi-- line protocol is down, why?

[jmaxwellUSAF]

GIVEN: 9300: vlan 8 SVI= 172.16.8.1 , #no shut

9300(config-if)# do sh int vlan 8
Vlan8 is down (VLAN/BD is down), line protocol is down, autostate enabled.

Symptom: "line protocol is down"

I expect the reason is in the below solution, but I don't understand the explanation, or how to implement it.

Questions: 1. What is "BD"?

2. May you please better explain the below solution-- what is the cause for the above symptom?

3. How do I implement the solution?

Thank you!

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Solved: Vlan shows down/down - Cisco Community

..."Interface vlan attaches a L3 svi to an already existing L2 vlan. Vlan database is being deprecated and you can create the L2 vlan with "vlan 7 " in global config. You will still need a L2 vlan configured for your L3 svi."

[MHM Cisco World · Accepted solution]

two point 
1- add VLAN to db by 
vlan 8 <<- add this command 

2- autostate enabled <<- disable autostate, and check the SVI is it UP 

[jmaxwellUSAF]

Interface and Hardware Components Configuration Guide, Cisco IOS XE Bengaluru 17.4.x (Catalyst 9300 Switches) - Configuring Interface Characteristics [Support] - Cisco

Layer 3 Interfaces

The device supports these types of Layer 3 interfaces:

• SVIs: You should configure SVIs for any VLANs for which you want to route traffic. SVIs are created when you enter a VLAN ID following the interface vlan global configuration command. To delete an SVI, use the no interface vlan global configuration command. You cannot delete interface VLAN 1.

  Note	When you create an SVI, it does not become active until it is associated with a physical port.

  When configuring SVIs, you can use the switchport autostate exclude command on a port to exclude that port from being included in determining SVI line-state. To disable autostate on the SVI, use the no autostate command on the SVI.

[MHM Cisco World]

You are so so welcome 

[jaydoer1]

Thank you

[BruteForce]

Hey, I actually messed with something similar recently.

BD stands for bridge domain. A bridge domain is a way to group together multiple VLANs (Virtual Local Area Networks) on some Cisco devices. This allows traffic to flow between the different VLANs within the bridge domain. I don't think this is relevant to what you're trying to solve though.

I believe your SVI is saying "line protocol is down" simply because it's essentially being unused, it's "sleeping". There needs to be at least one up interface within the vlan. You can make it up/up two ways. One, a device using an ip within that subnet needs to be connected to an access port. That'll bring it up/up. You'd be able to ping the gateway this way.

Two, what I do in labs that require an up/up SVI, is just add that layer 2 vlan to a trunk. This essentially makes the SVI "active". It's being tagged on a trunk link so it's up. The vlan doesn't even need to be configured on both sides of the trunk if your only goal is to make the SVI up/up. You can just make the SVI participate in OSPF or another routing protocol and it'll be reachable on the network.