Understanding sFlow Monitoring:

sFlow is a packet sampling technology used to monitor traffic in a network. It sends sampled packet data and interface counters to an sFlow collector, which analyzes the traffic patterns.

Information Included in sFlow Datagram:

Option A:The datagram sent to the sFlow collector includes information about the interface through which the packets entered the agent (the switch or router). This is crucial for understanding where in the network the traffic was captured.

Option D:sFlow datagrams also include the source and destination VLAN for the sampled packets. This allows for detailed analysis of the traffic flow within different VLANs.

Conclusion:

Option A:Correct—The ingress interface is included in the sFlow datagram.

Option D:Correct—The source and destination VLANs are also included, providing context for the sampled traffic.

Symmetric IRB Routing with EVPN Type 2 Routes:

Symmetric Routing: In symmetric IRB (Integrated Routing and Bridging), routing occurs in both directions at the ingress and egress leaf nodes using the same routing logic. This is contrasted with asymmetric routing, where different routing logic is used depending on the direction of the traffic.

Required Components:

Option A:An L3 IRB interface is necessary for each VLAN that participates in routing, as it handles the Layer 3 processing for the VLAN.

Option B:MAC-VRF is required for symmetric routing to maintain a mapping of MAC addresses to the appropriate VRF, ensuring correct forwarding within the EVPN.

Option D:A transit VNI (Virtual Network Identifier) is required for each VRF to encapsulate the Layer 3 traffic as it traverses the network, allowing the IP traffic to be appropriately forwarded.

Conclusion:

Option A:Correct—Each local VLAN needs an IRB interface for L3 processing.

Option B:Correct—MAC-VRF is necessary for handling MAC address resolution in symmetric routing.

Option D:Correct—Transit VNIs are required for routing VRF-specific traffic across the network.

OptionsCandEare incorrect because:

C:Symmetric routing can work with various VLAN models, including single or multiple VLANs within an EVPN instance.

E:Symmetric routing is generally more efficient than asymmetric routing as it uses consistent routing logic in both directions.

Understanding Oversubscription Ratio in IP Fabrics:

The oversubscription ratio in an IP fabric typically refers to the ratio of the available bandwidth at the edge of the network (leaves) to the available bandwidth at the core or spine. A 3:1 oversubscription ratio means that for every 3 units of bandwidth at the leaves, there is 1 unit of bandwidth at the spine.

Impact of Adding or Removing Leaf Devices:

Removing Leaf Devices:When you remove leaf devices, the amount of total edge bandwidth decreases while the bandwidth in the spine remains constant. This causes the oversubscription ratio toincreasebecause there is now less total bandwidth to distribute across the same amount of spine bandwidth.

Adding Leaf Devices:Conversely, when you add leaf devices, the total edge bandwidth increases. Since the spine bandwidth remains the same, the oversubscription ratio would remain the same if the additional leaves consume their share of the available bandwidth proportionally.

Conclusion:

Option C:Correct—Removing leaf devices increases the oversubscription ratio.

Option D:Correct—Adding leaf devices typically maintains the oversubscription ratio assuming uniform bandwidth distribution.

DHCP Behavior in Factory-Default Configuration:

Option B:In the factory-default configuration, Juniper switches are designed to send DHCP requests on all operational interfaces. This behavior ensures that the switch can obtain an IP address for management and further configuration from any available DHCP server.

Option D:The DHCP server can provide additional configuration parameters, including the required Junos version. This allows for automated provisioning and ensures that the switch is running the correct software version.

Conclusion:

Option B:Correct—The switch will use any operational interface to request an IP address via DHCP.

Option D:Correct—The DHCP server can specify Junos version requirements, enabling automated software management.

VXLAN Control Planes:

VXLAN (Virtual Extensible LAN) uses different control planes to handle MAC learning and traffic forwarding. The control planes include multicast and EVPN (Ethernet VPN).

Multicast and EVPN Comparison:

Option B:Both multicast and EVPN can be used for MAC learning in a VXLAN environment. Multicast is a more traditional approach, while EVPN is more advanced and supports distributed MAC learning.

Option D:EVPN offers benefits such as fast convergence and rapid updates, making it more efficient and scalable for modern data center environments.

Option E:Multicast does not require as many resources because it relies on traditional Layer 3 multicast mechanisms to distribute broadcast, unknown unicast, and multicast (BUM) traffic. However, it can be less flexible and less scalable compared to EVPN.

Conclusion:

Option B:Correct—Both control planes facilitate MAC learning.

Option D:Correct—EVPN provides fast convergence and updates.

Option E:Correct—Multicast is resource-efficient but less flexible.

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 References:

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.

Understanding ERB Architecture:

ERB (Edge Routed Bridging) architecture is a network design where the routing occurs at the edge (leaf devices) rather than in the spine devices. In a VXLAN overlay network with EVPN as the control plane, leaf devices typically act as both Layer 2 (L2) and Layer 3 (L3) VXLAN gateways.

Placement of VXLAN Gateways:

Option B:All leaf devices will have L2 VXLAN gateways to handle the bridging of VLAN traffic into VXLAN tunnels.

Option C:All leaf devices will also have L3 VXLAN gateways to route traffic between different VXLAN segments (VNIs) and external networks.

Option E:Spine devices in an ERB architecture generally do not function as VXLAN gateways. They primarily focus on forwarding traffic between leaf nodes and do not handle VXLAN encapsulation/decapsulation.

Conclusion:

Option B:Correct—All leaf devices will have L2 VXLAN gateways.

Option C:Correct—All leaf devices will have L3 VXLAN gateways.

Option E:Correct—Spine devices will not act as VXLAN gateways