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Which configuration is used to send and receive untagged packets through a trunk port?

Which configuration is used to send and receive untagged packets through a trunk port?

PrepAway - Latest Free Exam Questions & Answers

A.
[edit interfaces ge-0/0/4]
unit 10 {
family ethernet-switching {
port-mode access;
native-vlan-id 100;
}
}

B.
[edit interfaces ge-0/0/4]
unit 10 {
family ethernet-switching {
port-mode trunk;
native-vlan-id 100;
}
}

C.
[edit interfaces ge-0/0/4]
unit 10 {
family ethernet-switching {
port-mode access;
}
}

D.
[edit interfaces ge-0/0/4]
vlan-tagging;
unit 10 {
family ethernet-switching {
port-mode trunk;
native-vlan-id 100;
}
}

Explanation:
Trunk Mode
Trunk mode interfaces are generally used to connect switches to one another. Traffic sent between switches can then consist of packets from multiple VLANs, with those packets multiplexed so that they can be sent over the same physical connection. Trunk interfaces usually accept only tagged packets and use the VLAN ID tag to determine both the packets VLAN origin and VLAN destination. An untagged packet is not recognized on a trunk access port unless you configure additional settings on the port connected in access mode. In the rare case where you want untagged packets to be recognized on a trunk port, you must configure the single VLAN on the access port as native VLAN.

Trunk Mode and Native VLAN
With native VLAN configured, frames that do not carry VLAN tags are sent over the trunk interface. If you have a situation where packets pass from a device to a switch in access mode, and you want to then send those packets from the switch over a trunk port, use native VLAN mode. Configure the single VLAN on the switchs port (which is in access mode) as a native VLAN. The switchs trunk port will then treat those frames differently than the other tagged packets. For example, if a trunk port has three VLANs, 10, 20, and 30, assigned to it with VLAN 10 being the native VLAN, frames on VLAN 10 that leave the trunk port on the other end have no 802.1Q header (tag).

There is another native VLAN option. You can have the switch add and remove tags for untagged packets. To do this, you first configure the single VLAN as a native VLAN on a port attached to a device on the edge. Then, assign a VLAN ID tag to the single native VLAN on the port connected to a device. Last, add the VLAN ID to the trunk port. Now, when the switch receives the untagged packet, it adds the ID you specified and sends


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