Changed JN0-683 Exam Questions

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 References:

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.

Understanding Seamless Stitching:

Seamless stitching is used in EVPN to interconnect two data centers, allowing for consistent Layer 2 and Layer 3 connectivity across them. This is often achieved by translating VNIs (Virtual Network Identifiers) between the data centers.

Translation-VNI:

Option B:The translation VNI must be different in each data center to ensure that traffic can be correctly routed and distinguished as it crosses between the data centers. This differentiation helps to maintain the integrity of the traffic flows and prevents any potential overlap or conflict in VNIs.

Ethernet Segment Identifier (ESI):

Option D:The ESI must match in both data centers to ensure that the same Ethernet segment (which could be multihomed) is recognized consistently across the data centers. Matching ESIs are crucial for maintaining a unified view of the Ethernet segment across the interconnected fabric.

Conclusion:

Option B:Correct—Translation VNIs must be unique to each data center for proper traffic distinction.

Option D:Correct—Matching ESIs are necessary to maintain consistent Ethernet segment identification across both data centers.

VXLAN Overview:

VXLAN (Virtual Extensible LAN) is a network virtualization technology that encapsulates Layer 2 Ethernet frames into Layer 3 UDP packets for transmission over an IP network. It allows the creation of Layer 2 overlay networks across a Layer 3 infrastructure.

Understanding VXLAN Components:

VTEP (VXLAN Tunnel Endpoint):A VTEP is responsible for encapsulating and decapsulating Ethernet frames into and from VXLAN packets.

VNI (VXLAN Network Identifier):A 24-bit identifier used to distinguish different VXLAN segments, allowing for up to 16 million unique segments.

Correct Statements:

C. Layer 2 frames are encapsulated by the source VTEP:This is correct. In a VXLAN deployment, the source VTEP encapsulates the original Layer 2 Ethernet frame into a VXLAN packet before transmitting it over the IP network to the destination VTEP, which then decapsulates it.

A. A VXLAN packet does not contain a VLAN ID:This is correct. The VXLAN header does not carry the original VLAN ID; instead, it uses the VNI to identify the network segment. The VLAN ID is local to the switch and does not traverse the VXLAN tunnel.

Incorrect Statements:

B. The VNI must match the VLAN tag to ensure that the remote VTEP can decapsulate VXLAN packets:This is incorrect. The VNI is independent of the VLAN tag, and the VLAN ID does not need to match the VNI. The VNI is what the remote VTEP uses to identify the correct VXLAN segment.

D. The VNI is a 16-bit value and can range from 0 through 16,777,215:This is incorrect because the VNI is a 24-bit value, allowing for a range of 0 to 16,777,215.

Data Center References:

VXLAN technology is critical for modern data centers as it enables scalability and efficient segmentation without the constraints of traditional VLAN limits.

 Understanding the Problem:

Host1 (10.1.1.1) is failing to communicate with Host2 (10.1.2.1) within an EVPN-VXLAN environment using ERB architecture.

 Analysis of the Exhibit:

The provided output includes information from the show route forwarding-table matching command for IP 10.1.2.1. The next hop is shown as vtep.32769, which indicates that the traffic destined for 10.1.2.1 is being forwarded into the VXLAN tunnel with the correct VTEP (VXLAN Tunnel Endpoint).

 Conclusion:

Option B:Correct—The traffic from Host1 is entering the VXLAN tunnel, as evidenced by the next hop pointing to a VTEP. However, the issue could lie elsewhere, possibly with the remote VTEP, routing configurations, or the receiving leaf/spine devices.