JN0-683 Practice Exam Questions and Answers

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 Pure IP Fabric:

A pure IP fabric is a network design where all devices operate at Layer 3, meaning that each device in the fabric is a router that makes forwarding decisions based on IP addresses.

Layer 2 Support:

In a pure IP fabric, traditional Layer 2 protocols such as Spanning Tree Protocol (STP) or VLANs are not supported. Instead, the network relies entirely on Layer 3 routing protocols to manage traffic between devices.

Routing Functionality:

Since devices in an IP fabric operate as Layer 3 routers, they handle IP routing and provide network services based on IP addresses, not on MAC addresses or Layer 2 switching.

Conclusion:

Option A:Correct—Devices in an IP fabric function as Layer 3 routers.

Option D:Correct—A pure IP fabric does not support traditional Layer 2 protocols, making it a purely routed environment.

Multicast-Signaled VXLAN:

In traditional multicast-signaled VXLAN, VTEPs (VXLAN Tunnel Endpoints) use multicast to flood and learn about remote VTEPs. This method relies on multicast in the underlay network to distribute BUM (Broadcast, Unknown unicast, and Multicast) traffic.

This approach can be resource-intensive due to the need for multicast group management and increased network traffic, especially in large deployments.

EVPN-Signaled VXLAN:

EVPN-signaled VXLAN uses BGP (Border Gateway Protocol) to signal the presence of VTEPs and distribute MAC address information. BGP is used for VTEP autodiscovery and the distribution of endpoint information.

This method is more efficient because it reduces the reliance on multicast, instead using BGP control-plane signaling to handle VTEP discovery and MAC learning, which reduces the overhead on the network and improves scalability.

Correct Statements:

B.  

An EVPN-signaled VXLAN can perform autodiscovery of VTEPs using BGP:This is correct because EVPN uses BGP for VTEP autodiscovery, making it more efficient and scalable compared to multicast-based methods.

C.  

An EVPN-signaled VXLAN is less resource-intensive:This is correct because it eliminates the need for multicast flooding in the underlay, instead using BGP for signaling, which is less demanding on network resources.

Incorrect Statements:

A.  

An EVPN-signaled VXLAN can perform autodiscovery of VTEPs using IS-IS:This is incorrect because EVPN relies on BGP, not IS-IS, for VTEP discovery and signaling.

D.  

An EVPN-signaled VXLAN features slower and more complete convergence:This is incorrect; EVPN with BGP typically provides faster convergence due to its use of a control plane rather than relying on data plane learning.

Data Center References:

EVPN-VXLAN is widely adopted in modern data center designs due to its scalability, efficiency, and reduced resource consumption compared to multicast-based VXLAN solutions. It leverages the strengths of BGP for control-plane-driven operations, resulting in more efficient and scalable networks.