Which vlan is used for untagged traffic

This, along with all other trunk configuration, must be identical for the entire path through the network that traffic will follow. For example, if there are three switches between a client and a gateway on VLAN , it must be trunked through all the switches' connecting links shown below.

While VLANs are effective for separating network segments and limiting broadcast traffic, it is often a requirement for subnets separated by VLANs to be able to communicate.

This can be accomplished only through a layer 3-enabled device that can route between the VLANs. Even if both VLANs exist on a device, their traffic will be segregated unless mediated by a layer 3 routing device. There is communication between all the devices in the same VLAN and ping has been used to test this connectivity.

This means that the MAC address tables of the switches have already been populated with the correct port to MAC address mapping. To enable interVLAN communication, a layer 3 device is required.

In this scenario, PC will ping PC The configuration on the switch ports they are connected to is as follows:. Since these devices are on the same VLAN, communication will be permitted. However, since they are on different switches, the packets will need to be tagged on the trunk link between Switch1 and Switch2. Since this is a trunk port, the switch will include the VLAN tag of 20 hexadecimal 0x into the frame:.

Since this is an untagged packet received on a tagged port, Switch1 will associate that packet with the Native VLAN on that port. Since the packet is a broadcast packet destination address of FFFF. When Switch2 receives the untagged packet, it will also apply its own configured native VLAN to that packet and forward it appropriately:. VLAN Since the tag on this packet is different from the Native VLAN, the packet will be sent with its tag on:.

Scenario 3 above presents a potential problem — if traffic that matches the Native VLAN is sent untagged, what if there is a mismatch in the native VLAN on the trunk link between two switches? You can read more about this in this document. In response to veevekraj. Post Reply. Latest Contents. The IT Blog Awards is now accepting submissions! Created by caiharve on PM. Submit your blog, vlog or podcast today. They make geeky cool.

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Spotlight Award Nomination. Content for Community-Ad. Follow our Social Media Channels. Thank you! Thanks , very easily you explained about VLAN , honestly i was confused about tagg untagged and native vlan, now its cleared , thanks again. This article is very unique to a VLAN beginner like me. Being different from most if not all VLAN training materials, this article states that a tag is added on an access port when a frame comes in from a host.

While others claim that a tag is added on a trunk port, even the vdu on your YouTube channel says so. I may have phrased it badly. A frame entering an access port will become part of a VLAN.

If that frame is then forwarded over a trunk port, it will have a tag added. A frame leaving an access port will not be tagged. I think you made a mistake while explaining the traffic flow of tagged ports. DTP negotiates the actual trunk, Vs. You must be logged in to post a comment.

Below is a normal ethernet frame. Finally, the FCS is recalcualted based on the entire frame. The following diagram shows this process: The traffic flows like this: Host A sends traffic to the switch.

The switch then inserts the VLAN tag into the frame The switch determines that the frame needs to be forwarded out of port 2. Here, you can see this process in action: In this case, the following will happen: A host will send a frame without a tag The frame enters an untagged port on switch 1, configured with VLAN 10 in this case. The switch adds the VLAN tag to the frame Switch 1 determines that port 2 should send this frame to switch 2. This is a tagged port, so it checks that VLAN 10 is allowed on this port.

If it is, it leaves the tag intact, and sends the frame. This switch also determines if VLAN 10 is allowed on this port, and drops it if it is not. Switch 2 determines that port 2 should send the frame Since port 2 is an untagged port, it strips the tag from the frame, and then sends it Host B receives the untagged frame.

In short, the native VLAN is a way of carrying untagged traffic across one or more switches. Have a look at this diagram for an example: In this example, the two switches are connected with a trunk link. In general, use trunking to connect switches. Log in to Reply. Regards, Dave. Leave a Reply Cancel reply You must be logged in to post a comment.