What is the difference between PVID , untagged and tagged

Zyxel_Adam

Hi @businessuer


Thanks for reply.
To answer your question:

1. Step 1 and 3 will not overlap since step 3 is like assigning a port to a VLAN via the PVID you configured.
2. According to the scenario you provided, the port with PVID 3 ends up to VLAN 3. Since your scenario has no VLAN 3, so there is no any VLAN 3 traffic even you put PVID 3. 

Hope it helps.

businessuer

Ok but what if I also create vlan 2 and 3 in the vlan database?

Let say :

in step 1  create vlan 2 as well as vlan 3 in vlan database. 

in step 2  make vlan 2 untagged but the original vlan 1 is also untagged.

in step 3 make this port a PVID of vlan 3.

Now what will happen? 

What I mean is will step 2 and 3 overlap?
Does PVID 3 or untagged 2 takes precedence?
Why is vlan 1 untagged still there even though I create 2 and 3 ?

Zyxel_Adam

@businessuer

The scenario will not take any effect still since you did not configure VLAN 3 to untagged a port. 

Let me put in this way, refer to your scenario:
#I use port 10 as an example

VLAN 1, untagged port 10     |    port 10 PVID = 1

　　　　　　     　↓
　　　　　　     　↓　step.1 (Create VLAN)
　　　　　     　　↓

VLAN1, untagged port 10      |    port 10 PVID = 1
VLAN2,                                  |
VLAN3,                                  |

　　　　　     　　↓
　　　　　     　　↓    step.2 (VLAN 2, untagged port 10)
　　　　　     　　↓

VLAN1, untagged port 10      |    port 10 PVID = 1
VLAN2, untagged port 10      |
VLAN3, tagged     port 10      |

　　　　　     　　↓
　　　　　     　　↓    step.3 (Configure PVID 3 to port 10)
　　　　　     　　↓

VLAN1, untagged port 10      |    port 10 PVID = 3
VLAN2, untagged port 10      |
VLAN3, tagged port 10          |
--------------------------------------------------------------------------------------------
When port 10 receives packets, the behavior will be:
untagged packets → assign to VLAN 3
tagged     packets → assign to VLAN 1 and 2

When port 10 sends packets out, the behavior will be:
VLAN 3           → tagged packet out
VLAN 1 and 2 → untagged packet out


For your question:
What I mean is will step 2 and 3 overlap?
Step 2 and 3 will not overlap.

Does PVID 3 or untagged 2 takes precedence?
PVID takes higher priority

businessuer

When port 10 receives packets, the behavior will be:
tagged     packets → assign to VLAN 1 and 2

Dont understand this.

Send is egress and receive is ingress? 

Zyxel_Adam

@businessuer

Send is egress and receive is ingress? 
Yes, exactly. 

Is there anything unclear so far?

businessuer

When port 10 receives packets, the behavior will be:
tagged     packets → assign to VLAN 1 and 2

Dont understand this.