Why would a VLAN interface be down?
Administratively DOWN—The interface has been shut down by using the shutdown command. DOWN—The interface is administratively up, but its physical state is down. The VLAN of this VLAN interface does not contain any physical ports in up state. The ports might not be connected correctly or the links might have failed.
What is a VLAN sub interface?
VLANs enable a device to carry multiple discrete broadcast domains, allowing a single switch to function as if it were multiple switches.
What is a sub interface?
A subinterface is a virtual interface created by dividing one physical interface into multiple logical interfaces. A sub-interface in a Cisco Router uses the parent physical interface for sending and receiving data.
What is the purpose of a sub interface?
Subinterfaces divide the parent interface into two or more virtual interfaces on which you can assign unique Layer 3 parameters such as IP addresses and dynamic routing protocols. The IP address for each subinterface should be in a different subnet from any other subinterface on the parent interface.
Why line protocol is down Cisco router?
The line protocol being down indicates a clocking or framing problem. Probable reasons for this are encapsulation and clock rate mismatches. Ethernet0 is administratively down, line protocol is down: This output indicates that a local interface has been manually shut down using the shutdown command.
How many subinterfaces can a router support?
You can partition one physical interface into up to 4094 different subinterfaces, one for each VLAN.
What are the benefits of using VLANs?
The Real Advantages of a Virtual LAN (VLAN)
- help with network efficiency by reducing extraneous traffic;
- enhance security by creating a virtual boundary around that business unit;
- improve bandwidth performance by limiting node-to-node and broadcast traffic;
What does interface Down Down mean?
If the line shows up down then we believe that we have physical connectivity but no ability to transmit and receive on the interface. And if the interface shows up up then we have physical connectivity and the ability to transmit and receive on the interface. So down down indicates a problem with the connection.
What is the reason if protocol of an interface is down and status of an interface is up?
if the Line status is up,a protocol status of down usually is caused by mismatched data link layer configuration For an example serial interfaces has their combination when one router has configured to use PPP(Point_to_Point Protocol) and other remains the default HDLC (Higher_level Data Link Control) configuration and …