Which consideration must be taken into account when using the DHCP relay feature in a Cisco SD-Access Architecture?
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A. B. C. D.A.
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A. DHCP-relay must be enabled on fabric edge nodes to provide the correct mapping of DHCP scope to the local anycast gateway.
In Cisco SD-Access Architecture, the fabric edge nodes serve as the first hop for endpoints connecting to the network. When a device connects to the network, it sends a DHCP Discover message to obtain an IP address. However, because the fabric edge nodes in an SD-Access fabric are configured with anycast gateways, which share the same IP address, there is a need to map the DHCP scope to the local anycast gateway that the endpoint is connected to. This is where the DHCP relay feature comes into play. It allows the fabric edge nodes to forward the DHCP Discover message to the DHCP server and receive the DHCP Offer message, which contains the IP address and other configuration information. The DHCP relay feature must be enabled on the fabric edge nodes to provide the correct mapping of DHCP scope to the local anycast gateway.
B. A DHCP server must be enabled on the border nodes to allow subnets to span multiple fabric edges.
In an SD-Access fabric, the network is divided into virtual networks (VN) that are based on business needs. These VNs can span across multiple fabric edge nodes, which means that endpoints in the same VN could be connected to different fabric edge nodes. To allow subnets to span multiple fabric edges, a DHCP server must be enabled on the border nodes. The border nodes act as the gateways between the SD-Access fabric and external networks, and they are responsible for forwarding DHCP traffic to the appropriate DHCP server.
C. DHCP servers must support Cisco SD-Access extensions to correctly assign IPs to endpoints in an SD-Access fabric with anycast gateway.
The DHCP servers used in an SD-Access fabric must support Cisco SD-Access extensions to correctly assign IPs to endpoints. This is because the anycast gateway feature in an SD-Access fabric allows for multiple gateways to share the same IP address. When an endpoint connects to the network, it sends a DHCP Discover message, and the DHCP server needs to assign an IP address that corresponds to the correct anycast gateway. The Cisco SD-Access extensions enable the DHCP server to identify the correct anycast gateway based on the location of the fabric edge node that forwarded the DHCP request.
D. DHCP Option-82 must be enabled to map the circuit IP option to the access fabric node where the DHCP discover originated.
DHCP Option-82 is a DHCP relay agent information option that is used to provide additional information to the DHCP server about the network topology. In an SD-Access fabric, DHCP Option-82 must be enabled to map the circuit IP option to the access fabric node where the DHCP discover originated. This allows the DHCP server to identify the fabric edge node that forwarded the DHCP request and assign an IP address that corresponds to the correct anycast gateway. The circuit ID option contains the MAC address of the fabric edge node and the port number that the endpoint is connected to.