Solved

difference between trunk and tagged vlans...

Posted on 2010-11-24
5
980 Views
Last Modified: 2012-08-13
I know the cisco concept of trunk and access ports, i wanna know the difference between tagged ports and untagged ports in other vendor implementations like foundry etc...
0
Comment
Question by:tpat
  • 2
  • 2
5 Comments
 
LVL 34

Expert Comment

by:Istvan Kalmar
ID: 34210780
Hi,

Tagged port means = cisco trunk port
Unteagged port means = cisco access port

0
 
LVL 17

Expert Comment

by:Kvistofta
ID: 34210815
you can see each vlan as a channel or frequency. In an access-port you have only one channel (vlan) and therefore each packet doesnt need to be marked individually.

In a trunk, because you send traffic from different vlans in the same carrier, each packet needs to be marked (tagged), otherwise the remote end doesnt know which vlan each received packet belongs to.

Ok. So in a trunk, each packet is marked. But what if I (the switch) receive a NOT marked packet in a trunk? A packet that is not tagged belongs to what in Cisco-terms is called native vlan. This is by default vlan1 but can be configured differently.

In Cisco-terms we talk about trunks and which vlans that belongs to a specific port. But other vendors see it differently. For example HP Procurve where you configure this tagging per vlan and not per port. If you have a trunk port in a HP-switch you can add additional vlans as tagged to that port (tagged port) but only one vlan can be untagged on that port.  

If you have an access-port (in cisco-terms) which means that you have 0 tagged vlans and 1 tagged vlan, that is how the other end needs to be configured aswell.

If you in HP (or other vendors) add a previously unused switchport as tagged to a vlan, that means that this is (in cisco terms) a trunk that contains one single vlan, and that is tagged. This is in Cisco-switches configured as follows:

int gi0/x
 switchport mode trunk
 switchport trunk allowed vlan 123
 switchport trunk native vlan 1 (or whatever, except for 123)
!

Does this make sense?

/Kvistofta
0
 

Author Comment

by:tpat
ID: 34211007
your explanation was quite good,
but i dont understand
' If you have a trunk port in a HP-switch you can add additional vlans as tagged to that port (tagged port) but only one vlan can be untagged on that port'

What i know from cisco is a trunk port can carry traffic of multiple vlan's whereas an  access port only belongs to one vlan .
0
 
LVL 17

Accepted Solution

by:
Kvistofta earned 500 total points
ID: 34211134
Yes, you are right and there is no contradiction in what I wrote and what you are saying.

The technology is the same, no matter brand. The difference is the way to configure it. In HP you add ports to vlan, in Cisco you add vlans to ports.

What I say (that you quoted) is that in a trunk you can only have one untagged vlan. You cannot send multiple vlans as untagged. In the HP-world you configure vlan/ports by saying "add vlan x to port y as (un)tagged". If port y already was configured with an untagged vlan z, that vlan z will be removed from the port and vlan x will be the untagged (native) vlan instead.

/Kvistofta
0
 

Author Comment

by:tpat
ID: 34214350
i got it! thanks for helping Kvistofta!!
0

Featured Post

Secure Your Active Directory - April 20, 2017

Active Directory plays a critical role in your company’s IT infrastructure and keeping it secure in today’s hacker-infested world is a must.
Microsoft published 300+ pages of guidance, but who has the time, money, and resources to implement? Register now to find an easier way.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Short answer to this question: there is no effective WiFi manager in iOS devices as seen in Windows WiFi or Macbook OSx WiFi management, but this article will try and provide some amicable solutions to better suite your needs.
In this article, I am going to show you how to simulate a multi-site Lab environment on a single Hyper-V host. I use this method successfully in my own lab to simulate three fully routed global AD Sites on a Windows 10 Hyper-V host.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

685 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question