Inter-switch VLAN communication: Which technologies allow VLAN traffic tagging across switches? Options: ISL, VTP, 802.1Q, 802.3z
Networking
Virtual LANs
Difficulty: Medium
Choose an option
-
A2 only
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B1 and 3
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C2 and 4
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D2, 3 and 4
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E1 and 4
Answer
Correct Answer: 1 and 3
Explanation
Introduction / Context:Switch-to-switch VLAN communication requires trunking protocols that encapsulate VLAN membership inside Ethernet frames. Cisco and IEEE standards differ.
Given Data / Assumptions:
- Protocols listed: ISL (Cisco), VTP, 802.1Q, 802.3z
Concept / Approach:ISL and 802.1Q are VLAN trunking protocols. VTP is for VLAN database management, not tagging. 802.3z refers to Gigabit Ethernet physical standard, not VLAN tagging.
Step-by-Step Solution:
ISL: Encapsulates VLAN IDs.802.1Q: IEEE standard VLAN tagging.VTP: Only distributes VLAN info, no frame tagging.802.3z: Physical Gigabit spec, not VLAN-specific.Verification / Alternative check:Refer to Cisco docs: ISL and 802.1Q explicitly define VLAN tagging.
Why Other Options Are Wrong:
- VTP: Manages VLAN info, no frame encapsulation.
- 802.3z: Gigabit Ethernet, not trunking.
Common Pitfalls:Confusing VTP’s VLAN management with inter-switch tagging; mixing physical layer with encapsulation protocols.
Final Answer:1 and 3 (ISL and 802.1Q)