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VLANs/Trunks Notes Highlighted

Latest reply: Nov 24, 2018 02:03:56 615 2 2 0 0

The frame are tagged with a 4 Bytes field.

Possible VLAN are 4094 VLANs


There are three types of ports. Access, trunk or Hybrid.

  • An access port is called "untagged port"
  • An Trunk port is called "tagged port"
  • An Hybrid type permit to remove the tagging from one frame allowing an END device receive multiple traffic from multiples VLAN. (It is like a trunk with end devices).



Hybrid port is the DEFAULT TYPE of port.


To configure VLANs

[SWT] vlan batch 10 to 20 (To create all the VLAN between 10 to 20).

[SWT] display vlan 10 verbose (To show more details including the interfaces added to the VLAN).

[SWT] display vlan summary


To configure a trunk use

[Interface G0/1] port link-type TRUNK

[Interface G0/1] port trunk allow-pass vlan all



There are two ways to assigned a port to a VLAN

  1. Accessing to the VLAN and add the ports

[SWT] vlan 2

[SWT] port GigabithEthernet 0/1

  1. Accessing to the interface and added to the VLAN

[SWT] interface G/01

[SWT] port default vlan 2



[swt] Display vlan

The total number of vlans is : 4






UT:GE0/0/1 (U)



El "UT" significa "untagged" que puede ser porque el puerto esta en modo Access o Hybrid

 El "U" significa "UP" could be "D" from DOWN



Define a trunk port

[G0/1] port link-type trunk

Define the trunk mode

[G0/1] port trunk pvid vlan 10

Define the default VLAN of the trunk.

[G0/1] port trunk allow-pass vlan 2 3

Define the allowed VLAN's. You should add to VLAN 10 if you want to permit the traffic in that VLAN because even when is the default VLAN for the previous command won't be allowed if isn't in this list.



Define a hybrid Port

This kind of ports permit multiple VLANs to be untagged in the same port not only 1


[G0/1] port link-type  hybrid

 (By default are Hybrid mode so this command isn't necessary if the port has default configuration).

[G0/1] port hybrid pvid vlan 3

Define the default PVID that could be tagged or untagged. The PVID on a trunk like defines only the tagging behavior that will be applied at the trunk interface. ALL untagged traffic is tagged to VLAN 3. So from this example all traffic that came from VLAN 2 or VLAN 3 would be delivery tagged at VLAN 3.

[G0/1] port hybrid untagged vlan 2 to 3

Define which VLAN goes untagged. This means that any traffic forwarded from a host with VLAN 2 or 3 to an end system connected in this interface can be delivery
Broadcast sended by VLAN 2 or VLAN 3 will be received by this device.



Create subinterfaces in a router


[Router] interface G0/1.1

Create the subinterface.

[G0/1.1] dot1q termination vid 2

When received a packet, it will untagged and analyzed at level 3 to forwarding decision.

When send a packet, it will tagged the packet out with the current VID 2.

[G0/1.1] ip address 24


[G0/1.1] arp broadcast enable

It is necessa****ecause Broadcast ARP is disable by default in the subinterfaces.



Create a VLAN Interface

[SWT] Interface vlanif 2  

To create the interface VLAN

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Created Nov 24, 2018 01:33:12

Useful information, thanks for sharing!
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Created Nov 24, 2018 02:03:56

hi author , about S2700 device , can we configured it as L3 device ? i countered an issue , if i configured some vlanif interface , my network will be import some high latency delay , it effect my whole network . if you have some known experience , please help me solve my issue . thanks for your sharing and help .
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