Helping Hand Questions for JN0-683

Scenario Overview:

In the exhibit, Host A is trying to resolve Host B's IP address (10.10.1.2) through ARP (Address Resolution Protocol). Normally, an ARP request would be broadcasted over the network, and the host owning the IP address (Host B) would respond.

Role of Proxy ARP:

Option A:Proxy ARPallows a router or switch (in this case, leaf1) to respond to ARP requests on behalf of another host. Leaf1, knowing the MAC address of Host B through the EVPN MAC advertisement, can reply to Host A's ARP request directly without broadcasting the request across the entire network fabric. This feature reduces unnecessary traffic and increases network efficiency.

Conclusion:

Option A:Correct—Proxy ARP enables leaf1 to respond to Host A's ARP request for Host B's IP without broadcasting over the IP fabric, thus providing the ARP response locally.

Redundant Gateways in EVPN-VXLAN:

In an EVPN-VXLAN environment, providing redundant gateway functionality typically involves the use of Anycast Gateway. This allows multiple PEs (Provider Edge devices) to use the same IP address and MAC address for the gateway, enabling seamless failover and redundancy without IP conflicts.

Conserving Address Space:

Using the same IP address across multiple PEs conserves address space because only one IP address is needed for the gateway function, regardless of the number of PEs. The shared MAC address ensures that ARP resolution and forwarding behavior are consistent across all the PEs.

Conclusion:

Option C:Correct—Using IRB interfaces with the same IP and MAC address across all PEs satisfies the need for redundancy while conserving address space.

OptionsA, B,andDintroduce unnecessary complexity or do not fully utilize the efficient Anycast Gateway approach, which is best practice for conserving IP space and providing redundancy.

Type 2 EVPN Routes:

Type 2 routesadvertise MAC addresses within an EVPN instance and are used primarily for Layer 2 bridging. These routes do not require a VXLAN tunnel to the protocol next hop because they operate within the same Layer 2 domain.

Type 5 EVPN Routes:

Type 5 routesare used to advertise IP prefixes (Layer 3 routes) within EVPN. Similar to Type 2 routes, they do not require a VXLAN tunnel to the protocol next hop becausethey represent L3 routes, which are managed at the routing layer without the need for VXLAN encapsulation.

Conclusion:

Option B:Correct—Type 2 routes do not need a VXLAN tunnel to the next hop, as they are used for Layer 2.

Option D:Correct—Type 5 routes also do not need a VXLAN tunnel because they operate at Layer 3, handling IP prefixes.

Requirement Analysis:

The scenario requires a solution to interconnect two data centers that supports EVPN Type 2 connectivity. The solution must be highly scalable and must minimize the number of VXLAN tunnels between border leaf devices.

Understanding Type 2 Seamless Stitching:

Option D:Type 2 seamless stitchingis a method used in EVPN to provide Layer 2 connectivity (such as MAC address mobility) across different VXLAN segments. It is scalable because it allows only necessary tunnels to be established between border leaf devices, reducing the overhead of maintaining a full mesh of VXLAN tunnels.

Conclusion:

Option D:Correct—Type 2 seamless stitching satisfies the requirement by enabling scalable, efficient interconnection of two data centers with minimal VXLAN tunnels.