Cisco
352-001 · Question #76
352-001 Question #76: Real Exam Question with Answer & Explanation
The correct answer is B. They can be met, but require Ethernet to dot1q interworking between the PEs.. EoMPLS port mode transports raw Ethernet frames without requiring dot1q on the CE, making it suitable for legacy remote branches, but PE-to-PE interworking is required to bridge between port mode and dot1q at HQ.
Network Virtualization
Question
Refer to the exhibit. You are designing a Layer 2 VPN for a large financial company. Currently, 90% of traffic from the company's remote branches comes to HQ. The company has hubs and old switches at remotes that do not have dot1q capability. However, it does not have the budget to invest in new equipment at the remote branches. In addition to converting the remote branches to Layer 2 VPN, the company wants to connect all the branches to the HQ site, to ensure that the branches have access to dot1q capability. How can this customer's requirements be met, or if they cannot, why not?
Options
- AThey cannot be met, because an intelligent switch is required at the remote branches to enable
- BThey can be met, but require Ethernet to dot1q interworking between the PEs.
- CThey cannot be met, because EoMPLS in port mode requires VPLS.
- DThey can be met, but EoMPLS in port mode requires VPWS.
Explanation
EoMPLS port mode transports raw Ethernet frames without requiring dot1q on the CE, making it suitable for legacy remote branches, but PE-to-PE interworking is required to bridge between port mode and dot1q at HQ.
Common mistakes.
- A. EoMPLS port mode is specifically designed to avoid this requirement - it forwards all frames on a port transparently without any VLAN awareness on the CE, so no intelligent switch is needed at the remote branch.
- C. VPLS is a multipoint L2VPN technology and is entirely independent of EoMPLS port mode - EoMPLS port mode pseudowires operate as point-to-point circuits and have no dependency on VPLS.
- D. VPWS describes point-to-point L2VPN services (of which EoMPLS is one implementation), but stating that port mode 'requires VPWS' misidentifies the constraint - the actual issue is the need for PE interworking between port mode and dot1q, not a VPWS technology requirement.
Concept tested. EoMPLS port mode with Ethernet to dot1q PE interworking
Topics
#EoMPLS#L2VPN#dot1q interworking#pseudowire
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