why port is not assigned into vlan what is use of vlan without port

[krahulbgp]

why port is not assigned into vlan what is use of vlan without port ,in which perspective vlan without port is used ?

[Leo Laohoo]

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@krahulbgp wrote:
why port is not assigned into vlan

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Every switchport is assigned to a VLAN and VLAN 1 is the default.

[MHM Cisco World]

why port is not assigned into vlan' answer :- the port must assign to vlan' if you dont assign it by defualt it assign to vlan1

what is use of vlan without port' answer:- there is no vlan wiht port' vlan will not be up without interface' if you dont see vlab without port then check trunk port it allow this vlan

,in which perspective vlan without port is used ? There is no vlan without port

MHM

[Richard Burts]

It seems to me that the OP is asking 2 questions:

1) why port is not assigned into vlan. My colleagues have correctly answered this saying that any layer 2 switch port is assigned to a vlan. If there is not a specific vlan assignment then the default assignment of vlan 1 is used. If you just look at the running config it may look like some ports are not assigned, but that is because most things assigned by default do not show up in running config.

2) what is use of vlan without port ,in which perspective vlan without port is used. You can not have a port without a vlan but it is possible to have a vlan that has no local ports assigned. I wonder if this is what the OP is looking for. As an example think about an environment with 3 switches. switchA, switchB, and switchC. These switches are connected by trunks. switchA and switchC have configured vlans 1, 10, and 20 and have assigned ports to each of those vlans. switchB does not have any ports in vlans 10 or 20 but does need to forward those vlans over the trunk. switchB may need to configure those vlans (but not assign any ports to those vlans) so that trunk forwarding will work correctly.

[Martin L]

by default all ports are in vlan1 so when u unbox brand new switch, connect PCs to it, u have communication between PCs without any need to configure switch itself - default switch configs are OK. I think they call it "out-of-box ready-to-go" aka operational. 

2). SVI needs several things to be UP UP state so that u can configure or access (manage) switch remotely. SVI interface 1 needs to have vlan 1 present, vlan1 has to be assigned to port and that port must be up state, aka connected.  this is true for other SVI in other vlans if u add them later on. Of course, u also need IP assigned to SVI either by manually or DHCP - (some switches come with IP pre-configured and with GUI web access)

Regards, ML
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