JN0-480 Exam Dumps : Data Center Specialist (JNCIS-DC)

The deploy phase is the final step in the Juniper Apstra data center fabric design and deployment process. In this phase, you apply the Apstra-rendered configuration to the devices and verify the intent of the blueprint. Based on the web search results, we can infer the following actions are required during the deploy phase12:

• Assign device profiles to the blueprint. This action associates a specific vendor model to each logical device in the blueprint. Device profiles contain extensive hardware model details, such as form factor, ASIC, CPU, RAM, ECMP limit, and supported features. Device profiles also define how configuration is generated, how telemetry commands are rendered, and how configuration is deployed on a device. Device profiles enable the Apstra system to render and deploy the configuration according to the Apstra Reference Design34.
• Assign resources to the blueprint. This action allocates the physical devices, IP addresses, VLANs, and ASNs to the logical devices, networks, and routing zones in the blueprint. Resources can be assigned manually or automatically by the Apstra system. Assigning resources ensures that the blueprint has all the necessary elements to generate the configuration and deploy the fabric5 .
• Assign user roles to the blueprint. This action is not required during the deploy phase. User roles are defined at the system level, not at the blueprint level. User roles determine the permissions and access levels of different users in the Apstra system. User roles can be system-defined or custom-defined .
• Assign interface maps to the blueprint. This action is not required during the deploy phase. Interface maps are defined at the design phase, not at the deploy phase. Interface maps are objects that map the logical interfaces of a logical device to the physical interfaces of a device profile. Interface maps enable the Apstra system to generate the correct interface configuration for each device in the fabric . References:
• Deploy
• Deploy Device
• Device Profiles
• Juniper Device Profiles
• Resources

To answer this question, we need to understand the concept of ESI values in EVPN LAGs. An ESI is a 10-byte value that identifies an Ethernet segment, which is a set of links that connect a multihomed device (such as a server) to one or more PE devices (such as leaf switches) in an EVPN network. The same ESI value must be configured on all the PE devices that connect to the same Ethernet segment. This allows the PE devices to form an EVPN LAG, which supports active-active or active-standby multihoming for the device. The ESI value can be manually configured (type 0) or automatically derived from LACP (type 1) or other methods. In the exhibit, Server A is connected to two leaf switches (QFX 5210) using a LAG with LACP enabled. Server B is connected to three leaf switches (QFX 5120) using a LAG with LACP enabled. Based on this information, the following statements are correct about ESI values for the server connections to the fabric:

• C. A valid ESI value for Server A is 0x00.10.10.10.10.10.10.10.10.10. This is true because this ESI value can be automatically derived from the LACP configuration on the QFX 5210 devices. The LACP system ID is usually based on the MAC address of the device, and the LACP administrative key is a 2-byte value that identifies the LAG. For example, if the MAC address of the QFX 5210 device is 00:10:10:10:10:10 and the LAG ID is 10, then the LACP system ID is 00:10:10:10:10:10 and the LACP administrative key is 00:0A. The ESI value is then derived by concatenating the LACP system ID and the LACP administrative key, resulting in 00:10:10:10:10:10:00:0A. This ESI value can be represented in hexadecimal notation as 0x00.10.10.10.10.10.00.0A, or padded with zeros as 0x00.10.10.10.10.10.00.0A.00.00. This ESI value must be configured on both QFX 5210 devices that connect to Server A.
• D. A valid ESI value for Server B is 0x00.00.00.00.00.00.00.00.00.00. This is true because this ESI value is a reserved value that indicates a single-homed device. Server B is connected to three leaf switches (QFX 5120) using a LAG, but it is not multihomed to any of them. This means that Server B does not need an ESI value to form an EVPN LAG with any of the leaf switches. Instead, Server B can use the reserved ESI value of 0x00.00.00.00.00.00.00.00.00.00, which indicates that it is a single-homed device and does not participate in any EVPN LAG. This ESI value must be configured on all three QFX 5120 devices that connect to Server B. Thefollowing statements are incorrect about ESI values for the server connections to the fabric:
• A. A valid ESI value for Server A is 0x00.00.00.00.00.00.00.00.00.00. This is false because this ESI value is a reserved value that indicates a single-homed device. Server A is connected to two leaf switches (QFX 5210) using a LAG with LACP enabled, which means that it is multihomed to both of them. This means that Server A needs an ESI value to form an EVPN LAG with the leaf switches. The ESI value must be unique and non-zero for each Ethernet segment, so the reserved ESI value of 0x00.00.00.00.00.00.00.00.00.00 is not valid for Server A.
• B. A valid ESI value for Server B is 0x00.20.20.20.20.20.20.20.20.20. This is false because this ESI value is not derived from the LACP configuration on the QFX 5120 devices. Server B is connected to three leaf switches (QFX 5120) using a LAG with LACP enabled, but it is not multihomed to any of them. This means that Server B does not need an ESI value to form an EVPN LAG with any of the leaf switches. Instead, Server B can use the reserved ESI value of 0x00.00.00.00.00.00.00.00.00.00, which indicates that it is a single-homed device and does not participate in any EVPN LAG. The ESI value of 0x00.20.20.20.20.20.20.20.20.20 is not valid for Server B, and it may cause conflicts with other Ethernet segments that use the same ESI value. References:
• Ethernet Segment Identifiers, ESI Types, and LACP in EVPN LAGs
• Understanding Automatically Generated ESIs in EVPN Networks
• Ethernet Segment in EVPN: All You Need to Know

To implement ECMP in IP fabric using EBGP, you need to enable BGP to install multiple equal-cost paths in the routing table and to advertise them to the peers. The following actions are required to achieve this:

• B. Use a load balancing policy applied to BGP as an export policy. This is true because you need to apply a load balancing policy to BGP as an export policy to allow BGP to advertise multiple paths to the same destination to the peers. By default, BGP only advertises the best path to the peers, which prevents ECMP. A load balancing policy can be configured to match the desired routes and set the multipath attribute to true. This will enable BGP to advertise up to the maximum number of paths configured by the maximum-paths command. For example, the following configuration applies a load balancing policy to BGP as an export policy for the neighbor 10.10.10.1:

policy-statement load-balance { term 1 { from { route-filter 192.168.0.0/16 exact; } then { multipath; accept; } } } protocols { bgp { group ebgp { type external; neighbor 10.10.10.1 { export load-balance; } } } }

• C. Use the multipath multiple-as BGP parameter. This is true because you need to enable the multipath multiple-as BGP parameter to allow BGP to install multiple paths from different autonomous systems in the routing table. By default, BGP only installs multiple paths from the same autonomous system, which limits ECMP. The multipath multiple-as parameter can be configured under the BGP group or neighbor level. This will enable BGP to install up to the maximum number of paths configured by the maximum-paths command. For example, the following configuration enables the multipath multiple-as parameter for the BGP group ebgp:

protocols { bgp { group ebgp { type external; multipath multiple-as; } } }

The following options are incorrect because:

• A. Use a load balancing policy applied to the forwarding table as an export policy is wrong because applying a load balancing policy to the forwarding table does not affect the BGP advertisement or installation of multiple paths. A load balancing policy applied to the forwarding table only affects how the traffic isdistributed among the multiple paths in the forwarding table. It does not enable ECMP in BGP.
• D. Use a load balancing policy applied to BGP as an import policy is wrong because applying a load balancing policy to BGP as an import policy does not affect the BGP advertisement of multiple paths. A load balancing policy applied to BGP as an import policy only affects how the BGP routes are accepted or rejected from the peers. It does not enable ECMP in BGP. References:
• IP Fabric Underlay Network Design and Implementation
• Use ECMP to distribute traffic between two paths, one learned by eBGP and one learned by iBGP on a Cisco NX-OS switch
• Example: Configure an EVPN-VXLAN Centrally-Routed Bridging Fabric Using EBGP