What is VLAN Dot1q tag native?
The global command “vlan dot1Q tag native” is a common command found on ciscos devices which makes the native vlan on trunk ports require a tag or its dropped (essentially drops all untagged traffic on trunk ports).
What happens if you apply this command VLAN Dot1q tag native?
To maintain the tagging on the native VLAN and drop untagged traffic, use the vlan dot1q tag native command. The switch will tag the traffic received on the native VLAN and admit only 802.1Q-tagged frames, dropping any untagged traffic, including untagged traffic in the native VLAN.
What is the difference between VLAN and native VLAN?
The native VLAN is per trunk per switch configuration. The 802.1Q trunk port assigns untagged traffic on a native VLAN….Difference Between Default VLAN and Native VLAN.
| Criteria | Default VLAN | Native VLAN |
|---|---|---|
| Operand | Default VLAN is specified through the VLAN operand command. | Native VLAN is specified through the NATIVE operand command. |
Is native VLAN tagged or untagged?
In Cisco LAN switch environments the native VLAN is typically untagged on 802.1Q trunk ports. This can lead to a security vulnerability in your network environment. It is a best practice to explicitly tag the native VLAN in order to prevent against crafted 802.1Q double-tagged packets from traversing VLANs.
Should you change the native VLAN?
Changing the native VLAN is mostly related to preventing VLAN hopping attacks. If this is of a concern you should use a different native VLAN on trunk ports between switches. For safety, this should be a VLAN not in use in the network. You want every valid VLAN to be tagged between switches.
Does native VLAN need to be allowed on trunk?
By default, a trunk port sends traffic to and receives traffic from all VLANs. All VLAN IDs are allowed on each trunk. However, you can remove VLANs from this inclusive list to prevent traffic from the specified VLANs from passing over the trunk.
Do I need to allow native VLAN on trunk?
Cisco recommends not using VLAN 1, restricting VLAN 1 from trunk links ( switchport trunk allowed command), and not using a native VLAN on the trunks, meaning that all the VLANs on a trunk would be tagged, and there would be no VLAN 1 frames.
Which VLAN should be native?
VLAN 1
As VLAN 1 is the default native VLAN, it is used for untagged traffic. If you need to pass frames tagged VLAN 1, you will not be able to, by default. The solution is to change the default VLAN to another value. Once this is done, VLAN 1 can be passed across the trunk just the same as any other VLAN.
Is native VLAN allowed on trunk?
All VLAN IDs are allowed on each trunk. However, you can remove VLANs from this inclusive list to prevent traffic from the specified VLANs from passing over the trunk. You can add any specific VLANs later that you may want the trunk to carry traffic for back to the list.
Why might you want to change the native VLAN on a trunk?
What is the purpose of the native VLAN when configuring a trunk line?
What is the Native VLAN? As you remember from the previous lesson, trunk ports send and receive Ethernet frames tagged with IEEE 802.1q VLAN tags . The primary idea behind this is to be able to transport frames from multiple VLANs over a single physical link between switches.
Does VLAN Dot1q tag native work with trunking?
I can confirm that if vlan dot1q tag native is configured, a trunk always performs tagging on the outgoing frames (i.e. the native VLAN setting is ignored and all frames are tagged with the corresponding tag value). Untagged frames arriving at a trunk port will be dropped without being forwarded further.
What does Dot1q tag native do?
07-15-2018 02:50 PM So the switch with this command will tag the primary VLAN for outgoing traffic on the trunk, and reject all incoming untagged traffic, with the exception of control traffic. “Control traffic continues to be accepted as untagged on the native VLAN on a trunked port, even when the vlan dot1q tag native command is enabled.”
Which switch is better LACP or PAgP?
If you need form the etherchannel on stack switch, it is better to choose LACP since LACP support cross-stack Etherchannel. The PAgP doesn’t support cross-stack etherchannel on cisco3750 .
What is a native VLAN?
The native VLAN is a concept retaken from 802.1Q standard that states that each port has a Primary VLAN ID (the native VLAN in Cisco parlance), and may have additional VLAN IDs (tagged VLANs). In order to be compatible with 802.1Q, each device has to implement this concept, resulting into Cisco’s native VLANs on trunks.