Layer 2 Network Scalability and Segmentation for Multitenant Data Centers | Cisco Exam 400-151

Best Layer 2 Technology for Scalable Multitenant Data Centers

Question

A cloud service provider is designing a large multitenant data center to support thousands of tenants.

The provider is concerned about the scalability of the Layer 2 network and providing Layer 2 segmentation to potentially thousands of tenants.

Which Layer 2 technology is best suited in this scenario?

Answers

Explanations

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A. B. C. D.

A.

In a large multitenant data center, providing Layer 2 segmentation to potentially thousands of tenants can be a challenging task. The Layer 2 network scalability can be an issue in this scenario, as the number of tenants increases, which can lead to problems such as broadcast storms, MAC address table overflow, and inefficient use of bandwidth.

To address these challenges, various Layer 2 technologies can be used, including VXLAN, VRF, extended VLAN ranges, and LDP.

A. VXLAN (Virtual Extensible LAN) is a Layer 2 overlay technology that allows the creation of virtual Layer 2 networks over an existing Layer 3 infrastructure. VXLAN encapsulates Layer 2 traffic in UDP packets, which are then transmitted over the Layer 3 network. VXLAN uses a 24-bit identifier called the VXLAN Network Identifier (VNI) to create multiple virtual Layer 2 networks over the same Layer 3 infrastructure, providing scalability and flexibility in multitenant environments.

VXLAN is well suited for this scenario because it provides Layer 2 segmentation for potentially thousands of tenants while overcoming the scalability limitations of traditional Layer 2 networks. VXLAN also offers better utilization of bandwidth and supports workload mobility across physical hosts and data centers.

B. VRF (Virtual Routing and Forwarding) is a Layer 3 technology that allows the creation of multiple virtual routing instances on a single physical router or switch. Each VRF instance has its own routing table and forwarding table, providing Layer 3 segmentation and isolation between tenants.

While VRF can provide Layer 3 segmentation, it may not be the best-suited technology for Layer 2 segmentation. VRF can be complex to deploy and manage, and it does not provide the same level of scalability and flexibility as VXLAN.

C. Extended VLAN ranges allow the expansion of the VLAN identifier space from the traditional 12-bit VLAN identifier to a larger space, such as 24-bit or 32-bit. This enables the creation of a larger number of VLANs, which can be used to provide Layer 2 segmentation for multiple tenants.

However, extended VLAN ranges have limitations in terms of scalability and do not address the broadcast storm and MAC address table overflow issues that can occur in large Layer 2 networks.

D. LDP (Label Distribution Protocol) is a Layer 2 technology that is used for MPLS (Multiprotocol Label Switching) networks. LDP distributes labels between routers to create label-switched paths, which can be used to forward traffic across the network.

While LDP can provide some degree of Layer 2 segmentation, it is not well suited for large multitenant data centers, as it lacks the scalability and flexibility of VXLAN.

In conclusion, VXLAN is the best-suited Layer 2 technology for this scenario, as it provides Layer 2 segmentation for potentially thousands of tenants while overcoming the scalability limitations of traditional Layer 2 networks.