Requirements for AI Workloads:

The scenario requires a network that supports at least 400 Gbps Ethernet and does not require Layer

2 VLANs. This setup is well-suited for a pure Layer 3 network, which can efficiently route traffic

between devices without the overhead or complexity of maintaining Layer 2 domains.

Choosing the Right Network Architecture:

Option D: An IP fabric using EBGP (External BGP) is ideal for this scenario. In a typical IP fabric, EBGP

is used to handle routing between spine and leaf switches, creating a scalable and efficient network.

Since there is no need for Layer 2 VLANs, the pure IP fabric design with EBGP provides a

straightforward and effective solution.

Options A, B, and C involve more complex architectures (like VXLAN or EVPN), which are unnecessary

when there's no requirement for Layer 2 overlays or VLANs.

Conclusion:

Option D: Correct—An IP fabric with EBGP is the most suitable and straightforward architecture for a

network that needs to support high-speed AI workloads without Layer 2 VLANs.

Understanding VXLAN Tunneling:

VXLAN (Virtual Extensible LAN) is a network virtualization technology that addresses the scalability

issues associated with traditional VLANs. VXLAN encapsulates Ethernet frames in UDP, allowing Layer

2 connectivity to extend across Layer 3 networks.

Each VXLAN network is identified by a unique VXLAN Network Identifier (VNI). In this exhibit, we

have two VNIs, 5100 and 5200, assigned to the VXLAN tunnels between leaf1 and leaf2.

Network Setup Details:

Leaf1: Connected to Server1 with VLAN ID 100 and associated with VNI 5100.

Leaf2: Connected to Server2 with VLAN ID 200 and associated with VNI 5200.

Spine: Acts as the interconnect between leaf switches.

Traffic Flow Analysis:

When traffic is sent from Server1 to Server2, it is initially tagged with VLAN ID 100 on leaf1.

The traffic is encapsulated into a VXLAN packet with VNI 5100 on leaf1.

The packet is then sent across the network (via the spine) to leaf2.

On leaf2, the VXLAN header is removed, and the original Ethernet frame is decapsulated.

Leaf2 will then associate this traffic with VLAN ID 200 before forwarding it to Server2.

Correct Interpretation of the Exhibit:

The traffic originating from Server1, which is tagged with VLAN ID 100, will be encapsulated into

VXLAN and transmitted to leaf2.

Upon arrival at leaf2, it will be decapsulated, and since it is associated with VNI 5200 on leaf2, the

traffic will be retagged with VLAN ID 200.

Therefore, the traffic will reach Server2 tagged with VLAN ID 200, which matches the network

configuration shown in the exhibit.

Data Center Reference:

This configuration is typical in data centers using VXLAN for network virtualization. It allows isolated

Layer 2 segments (VLANs) to be stretched across Layer 3 boundaries while maintaining distinct VLAN

IDs at each site.

This approach is efficient for scaling large data center networks while avoiding VLAN ID exhaustion

and enabling easier segmentation.

In summary, the correct behavior, as per the exhibit and the detailed explanation, is that traffic sent

from Server1 will be tagged with VLAN ID 200 when it reaches Server2 via leaf2. This ensures proper

traffic segmentation and handling across the VXLAN-enabled data center network.

Understanding VRF and Routing Instances:

In an EVPN-VXLAN overlay network, multiple tenants are separated using unique VRF (Virtual

Routing and Forwarding) instances. Each VRF instance maintains its own routing table, allowing for

isolated routing domains within the same network infrastructure.

Role of Route Distinguisher:

Route Distinguisher (RD): The RD is a unique identifier used in MPLS and EVPN environments to

distinguish routes belonging to different VRFs. The RD is prepended to the IP address in the route

advertisement, ensuring that routes from different tenants remain unique even if they use the same

IP address range.

Correct Property:

D. the route distinguisher value: This is the correct answer because the RD is crucial in determining

which routing information belongs to which VRF instance. It ensures that each VRF’s routing table

only contains relevant routes, maintaining isolation between tenants.

Data Center Reference:

The RD is a key element in MPLS and EVPN-based multi-tenant environments, ensuring proper

routing segregation and isolation for different VRFs within the data center fabric.

Understanding Bridged Overlay Architecture:

In a single-tenant data center using a bridged overlay architecture, virtual networks (VLANs) are

typically isolated within the fabric, with traffic between these VLANs handled outside the fabric.

Communication Between Different Virtual Networks:

A . off-fabric using an external device: This is correct. In many bridged overlay architectures,

communication between different virtual networks is handled off-fabric, often using an external

router or firewall that connects the different VLANs. The fabric itself primarily provides Layer 2

connectivity within each VLAN, leaving inter-VLAN routing to be handled externally.

Data Center Reference:

This design is common in smaller or simpler data center environments where a single tenant does

not require complex on-fabric routing and prefers to handle inter-VLAN routing through dedicated

devices.

Understanding Multihomed CE-to-PE VXLAN Environment:

In a VXLAN environment using EVPN signaling, multiple PEs (Provider Edge devices) can be

connected to the same CE (Customer Edge device). This setup is referred to as multihoming, where a

CE device has multiple connections to the network to ensure redundancy and load balancing.

Role of the Designated Forwarder:

The designated forwarder (DF) is a mechanism used in EVPN to manage the forwarding of broadcast,

unknown unicast, and multicast (BUM) traffic in a multihomed environment. The DF is selected to

ensure that only one of the PEs forwards this type of traffic to the CE, preventing loops and

unnecessary duplicate packets.

Avoiding Duplicate Packets:

Without a designated forwarder, all PEs connected to a multihomed CE could potentially forward the

same packet to the CE, resulting in duplicate packets. This duplication can cause issues with packet

processing on the CE, leading to inefficiencies and potential network problems.

Conclusion:

Option D: Correct—The designated forwarder is essential to prevent duplicate packets from being

received on multihomed hosts, ensuring that only one PE forwards BUM traffic to the CE.

In this scenario, you want the border leaf device to advertise Type 5 EVPN routes to another border

leaf in a different data center. Type 5 routes in EVPN are used to advertise IP prefixes, which means

that for proper route advertisement, you need to configure the correct settings within the evpn

hierarchy.

Step-by-Step Analysis:

Understanding EVPN Type 5 Routes:

EVPN Type 5 routes are used to advertise IP prefixes across EVPN instances, which allow different

data centers or networks to exchange routing information effectively.

VRF Target Setting:

The vrf-target configuration is crucial because it defines the export and import policies for the VRF

within the EVPN instance. For EVPN Type 5 routes to be advertised to other border leaf devices, the

vrf-target needs to be correctly configured under the evpn hierarchy, not just within the routing

instance.

Command to solve this:

move vrf-target target:65000:1 to evpn

Other Options:

Option B: Adding a VLAN configuration would not address the requirement to advertise Type 5

routes.

Option C: Adding VXLAN encapsulation may be necessary for other scenarios but does not directly

address the Type 5 route advertisement.

Option D: Changing the route-distinguisher will differentiate routes but does not impact the

advertisement of Type 5 routes to other data centers.

By moving the vrf-target to the evpn hierarchy, you enable the proper route advertisement, ensuring

that the Type 5 routes for local networks are shared with other data center border leaf devices. This

is aligned with best practices for multi-data center EVPN implementations, which emphasize the

correct placement of routing policies within the EVPN configuration.

Understanding the Scenario:

EVPN-VXLAN deployments often involve scenarios where multiple tenants or applications require

overlapping VLAN IDs, which can be managed using the mac-vrf routing instance type. This allows

you to segregate traffic within the same VLAN ID across different tenants.

Host-facing Interface Configuration:

A . Host-facing interfaces must be configured using a service-provider style configuration: This is

correct. In mac-vrf configurations, host-facing interfaces (those connecting end devices) typically

follow a service-provider style configuration, where each customer or tenant's traffic is isolated even

if overlapping VLAN IDs are used.

B . Host-facing interfaces must be configured using enterprise-style configuration: This is incorrect for

mac-vrf instances because enterprise-style configurations are more common in simpler, less

segmented networks.

Routing Instance Service Type:

D . The routing-instance service type can be VLAN-based: This is correct. The service type in mac-vrf

can indeed be VLAN-based, which is particularly useful in scenarios where VLAN ID overlap is needed

between different tenants or services.

Data Center Reference:

The mac-vrf instance type is powerful for handling complex multi-tenant environments in EVPN-

VXLAN, especially when dealing with overlapping VLAN IDs across different segments of the

network.

MAC Move Limiting:

MAC move limiting is a security feature used in network switches to detect and mitigate rapid

changes in MAC address locations, which could indicate a network issue or an attack such as MAC

flapping or spoofing.

When a MAC address is learned on a different interface than it was previously learned, the switch

can take various actions to prevent potential issues.

Available Actions:

A . drop: This action drops packets from the MAC address if it violates the move limit, effectively

blocking communication from the offending MAC address.

D . log: This action logs the MAC move event without disrupting traffic, allowing network

administrators to monitor and investigate the event.

E . shutdown: This action shuts down the interface on which the MAC address violation occurred,

effectively stopping all traffic on that interface to prevent further issues.

Other Actions (Not Correct):

B . filter: Filtering is not typically associated with MAC move limiting; it generally refers to applying

ACLs or other mechanisms to filter traffic.

C . enable: This is not an action related to MAC move limiting, as it does not represent a specific

reaction to a MAC move event.

Data Center Reference:

MAC move limiting is crucial for maintaining network stability and security, particularly in

environments with dynamic or large-scale Layer 2 networks where MAC addresses might frequently

change locations.

Telemetry in Data Centers:

Telemetry allows for real-time monitoring of network devices by collecting and exporting data such

as interface statistics, routing table updates, and other key metrics.

Vendor-Neutral Data Models:

Option A: JTI (Junos Telemetry Interface) OpenConfig sensors use a vendor-neutral data model,

which is important for ensuring compatibility across different network devices and systems.

OpenConfig is an industry-standard model, which facilitates integration with various telemetry

collection systems.

Conclusion:

Option A: Correct—OpenConfig sensors provide a vendor-neutral solution for telemetry, ensuring

broad compatibility and flexibility in data center environments.

Understanding Lossless Ethernet and Congestion Management:

Lossless Ethernet is crucial for AI and ML workloads, where packet loss can significantly degrade

performance. To implement lossless Ethernet, congestion management protocols like ECN (Explicit

Congestion Notification) are used.

Role of ECN in Congestion Management:

Option A: In an IP fabric that supports lossless Ethernet, when a switch experiences congestion, it can

mark packets using ECN. This marking notifies the source device of the congestion, allowing the

source to reduce its transmission rate, thereby preventing packet loss.

Conclusion:

Option A: Correct—The switch experiencing congestion notifies the source device via ECN marking.