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Zorluk: OrtaSwitching Concepts and VLANs

A computer connected to Switch 1 on an access port assigned to VLAN 40 sends a unicast Ethernet frame to a server connected to Switch 2 on an access port also assigned to VLAN 40. The two switches are interconnected by an 802.1Q trunk link where VLAN 40 is configured as the native VLAN on both sides. What happens to the IEEE 802.1Q header of the frame as it travels from the sending computer to the receiving server?

  1. The frame remains untagged throughout its entire transmission from the source computer to the destination server.Cevap
  2. B
    Switch 1 adds an 802.1Q header with VLAN ID 40 across the trunk link, and Switch 2 strips the header before sending it to the server.
  3. C
    The sending computer inserts an 802.1Q tag header before transmitting the frame onto the network access port.
  4. D
    Switch 1 drops the frame because traffic belonging to the native VLAN cannot cross an 802.1Q trunk link without a Layer 3 router.

Cevap

The frame remains untagged throughout its entire transmission from the source computer to the destination server.
Under the IEEE 802.1Q standard, traffic associated with the native VLAN is sent across a trunk link untagged. Since the sending host sends an untagged frame, Switch 1 forwards it untagged across the trunk, and Switch 2 delivers it untagged to the receiving server, the frame stays untagged along the entire path.

Adım Adım Çözüm

1
Analyze host-to-switch egress on access port
The source computer sends a standard untagged Ethernet frame to Switch 1.
Standard end hosts on access ports do not append IEEE 802.1Q tags to outgoing Ethernet frames.
2
Determine trunk encapsulation behavior for the native VLAN
Switch 1 identifies the frame as belonging to VLAN 40, which matches the native VLAN of the 802.1Q trunk, and forwards it across the trunk link without adding a tag.
By default under the IEEE 802.1Q standard, frames belonging to the native VLAN are forwarded untagged across trunk links.
3
Analyze trunk ingress and access port egress on the receiving switch
Switch 2 receives the untagged frame on its trunk port, maps it to its native VLAN (VLAN 40), and delivers it untagged out the destination access port to the server.
Untagged frames received on an 802.1Q trunk port are automatically placed into the configured native VLAN.

Anahtar Kavram

802.1Q Native VLAN Trunking Behavior
Tahmini Süre:1m 15s
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Konular

Switching Concepts and VLANs

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