Switches, Hubs, and Modems

Re: Tagged vs. Untagged

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New Member

Re: Tagged vs. Untagged

Real World Example :

I think of it as baggage at an airport, if you only have one destination you don't need a luggage tag, therefore untagged. If it needs to transit through then it will need a label to show the destination and therefore tagged. Switches are your airports, so every uplink or downlink transits between airports and therefore will have tagged vlans. Every switch to switch link generally has the default vlan untagged and all others tagged for transit.

Computers rarely understand vlans (not servers) and so their ports will untagged in a single vlan. IP Phones and other smart devices generally know about vlans so if you have a daisy chain of an IP phone and then a computer the port will most likely have a tagged VoiP vlan and an untagged computer vlan. I generally use the default vlan as a management vlan with it's own separate IP range, in our case 192.168.xxx.xxx and the work vlans in a class B subnet, if you use a flat IP range for all then you are wasting the power of the HP Procurve.

New Member

Re: Tagged vs. Untagged

In your reply you say "untagged - means that if there is packets on this port that have no vlan id set will have their vlan id tag set to this vlan by the switch. Packets that do have a vlan tag with this vlan id will bei ignored." Do you mean dropped when you say ignored or passed on as received with the VLAN tagging intact?

New Member

Re: Tagged vs. Untagged

Hi. Ignored packets will be DROP without communication. 

Occasional Advisor

Re: Tagged vs. Untagged

So, a followup clarification, Eric:

Any given physical switchport can have

  • Zero to many tagged VLANs


  • Zero or one untagged VLANs

at the same time; that is correct?

Occasional Contributor

Re: Tagged vs. Untagged

Can some one please explain this. 

int range fa0/1-22

Switchprot mode access 

switchport access vlan 10

switchport voice vlan 20

int fa0/23

switchmode mode turnk

switchport trunk allowed vlan 10, 20


Can some one please help me it's equivlant in HP switches.



Occasional Visitor

Re: Tagged vs. Untagged

1- int fa 0/23........ means you have entered into port configuration(port 23 on switch ) of switch.

2- switchport model access.......means you have activited access mode on port.

3-switchport access vlan 10....... means you have configured vlan 10 on port 0/23.

4-switchport voice vlan 20.......means now you have configured vlan 20 for VOIP(Voice Over IP) phones on same port(0/23).

Occasional Visitor

Re: Tagged vs. Untagged

1- int fa 0/23 means you have entered into port configuration of switch.

2- switchport mode trunk...means now u are using trunk port and u are configuring trunk mode on port 23(trunk mode allow more than 1 vlan to pass through 1 port of swtich to pc(computer))..

3 switchport trunk allowed vlan 10 ,20.......means now u are configuring vlan 10 and vlan 20 on port 23 of switch...and allow the port to send two vlans(10,20) to another switch.....


->>>  must go through the trunk and access mode on google....make your concepts clear before start of this


Occasional Visitor

Re: Tagged vs. Untagged


int fa0/23 stands for.....interface fastethernet 0/23..


explaination.....infaceface means which bport on switch......fastethernet means you are using port of fastethernet which gives u speed of 100mpbs means normal speed not more than GigabitEthernet port.........0/23 means 0 means nothing here but 23 means swtich port number ....like now u have switch of cisco that having 24 lan ports...and u are using 23 port no for configuration.....


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