Why VLAN line protocol is down?
On Cisco switches, after creating a new VLAN, we have noticed that VLAN interface is up however protocol doesn’t come up.
MTSTJCORESW#sh int vlan 10
Vlan10 is up, line protocol is down
Hardware is Ethernet SVI, address is 00fe.a5c8.c9ce (bia 00fe.a5c8.c9ce)
Internet address is 10.10.10.1/24
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive not supported
ARP type: ARPA, ARP Timeout 04:00:00
Last input never, output never, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 packets output, 0 bytes, 0 underruns
0 output errors, 3 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
This is because of Autostate feature that is implemented on Cisco switches with CatOS and IOS platforms and also activated by deafult. On IOS based switches, this feature cannot be disabled however on CatOS based switches, this feature can be disabled.
In order to resolve this, atleast one switch port must be configured on this VLAN and has link up (connect a device on this VLAN).
switchport access vlan 10
switchport voice vlan 10
Another option is to have a trunk port on the switch with this VLAN allowed.
switchport trunk allowed vlan all
switchport trunk allowed vlan 10