Any port can carry one untagged VLAN and any number of tagged VLANs. In some models port mode has to be changed if it is going to be assigned to a tagged VLAN.
Dell switches have three modes for a switch port:
I- access: port can be assigned to only one untagged VLAN
II- trunk: port can be assigned to as many as tagged VLANs
III- general: port can be assigned to one untagged VLAN and as many as tagged VLANs
Cisco switches have two modes
I- access: port can be assigned to only one untagged VLAN
II- trunk: port can be assigned to one untagged VLAN and as many as tagged VLANs
In HP and Brocade switches configuration is done under the VLAN configuration context.
In Cisco and Dell switches configuration is done under port configuration context.
- HP: First VLAN is created and then ports are assigned.
Any port can be added to as many as tagged VLAN s and one untagged VLAN.
The following commands put port 2 in tagged VLAN 666 and port 4 in untagged vlan 666
# vlan 666
# tagged ethernet 2
# untagged ethernet 4
- Brocade/Foundry: The default mode is that the port is either tagged or untagged. If a port is going to carry both tagged and untagged frames then it has to be defined as dual-mode. In order to make a port dual-mode first we have to make sure that it is not untagged in any VLAN.
The following commands implement this: Port 2 untagged VLAN 666 and tagged VLAN 55
# vlan 666
# no untagged ethernet 2
# tagged ethernet 2
# interface ethernet 2
# dual-mode 666
# vlan 55
# tagged ethernet 2
An interface in Brocade has three possibilities:
1- Only one untagged VLAN
2- As many as tagged VLANs but no untagged
3- One untagged and as many as tagged VLANs, in this case the untagged VLAN has to be defined as dual-mode under interface configuration
SSH@core1>show vlan 10
PORT-VLAN 10, Name 151Front, Priority level0, in single spanning tree domain
Untagged Ports: (U1/M1) 13 14 15 16 17 18 19 20
Tagged Ports: (U1/M1) 4 5 6 7 9 10 11 12 21 22 23
Uplink Ports: None
DualMode Ports: (U1/M1) 8
Mac-Vlan Ports: None
Monitoring: Disabled
- Dell switch ports have 3 modes:
access: only untagged traffic
trunk: only tagged traffic
general: both tagged and untagged
The following commands configure port 2 in access mode and in VLAN 666
# interface ethernet 2
# switchport mode access (by default the port is untagged VLAN 1)
# switchport access vlan 666 (changes the port to untagged VLAN 666)
# switchport portfast (only possible in access mode to disable Spanning-Tree)
# no switchport access vlan (removes it from VLAN 666 and back to default VLAN 1)
The following commands configure port 2 in trunk mode and therefore it can be added to any number of tagged VLANs:
# interface ethernet 2
# switchport mode trunk
# switchport trunk allowed vlan add/remove 666 (tagged VLAN 666)
# switchport trunk allowed vlan add/remove 55 (tagged VLAN 55)
The following commands configure port 2 in general mode and therefore it can be added to as many as tagged VLAN s and one untagged VLAN (pvid)
# interface ethernet 2
# switchport mode general
# switchport general allowed vlan add/remove 666 (tagged VLAN 666)
# switchport general pvid 55 (untagged VLAN 55)
- Cisco switch ports have two modes:
access: only untagged traffic
trunk: both tagged and untagged
The following commands configure port 2 in access mode and in untagged VLAN 666
# interface ethernet 2
# switchport mode access (by default the untagged VLAN is 1)
# switchport access vlan 666 (untagged VLAN 666)
# switchport portfast (only possible in success mode to disable Spanning-Tree)
The following commands configure port 2 in trunk mode so it can be added to as many as tagged VLAN s and one untagged VLAN (native VLAN)
# interface ethernet 2
# switchport mode trunk
# switchport trunk allowed vlan 666 (tagged VLAN 666)
# switchport trunk native vlan 55 (untagged VLAN 55)
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