Cisco SD-Access Solution Flashcards
Some key benefits about the Cisco SD-Access solution are listed below:
The fabric enables stretched subnets, which allow an IP subnet to be stretched via the overlay. STP as the solution is routed access and allows Equal-Cost Multipath (ECMP). Therefore, packet forwarding to a single destination can occur over multiple best paths with equal routing priority.
The fabric enables local switching of WLAN traffic at the edge node with the help of the anycast gateway. With the Cisco DNA Center acting as a single pane of glass, it allows centralized automation, contextual visibility, and troubleshooting. The fabric enables any service or policy on any port. The fabric enables two levels of segmentation for both LAN and WLAN with the help of a virtual network (or virtual routing and forwarding [VRF]) and scalable group tag (SGT). The fabric enables seamless mobility for users and endpoints and policy is applied end-to-end.
Cisco SD-Access Fabric Terminology
Underlay network: The underlay network is defined by physical switches and routers that are part of the campus fabric. All network elements of the underlay must establish an IP connectivity via the use of a routing protocol. Theoretically, any topology and routing protocol can be used, but the implementation of a well-designed Layer 3 foundation to the campus edge is highly recommended to ensure performance, scalability, and high availability of the network. In the campus fabric architecture, end-user subnets are not a part of the underlay network.
Overlay network: An overlay network runs over the underlay to create a virtualized network. Virtual networks isolate both data plane traffic and control plane behavior among the virtualized networks from the underlay network. Virtualization is achieved inside the campus fabric by encapsulating user traffic over IP tunnels that are sourced and terminated at the boundaries of the campus fabric. The fabric boundaries include borders for ingress and egress to a fabric, fabric edge switches for wired clients, and fabric APs for wireless clients. Network virtualization extending outside of the fabric is preserved by using the traditional virtualization technologies such as VRF-Lite and MPLS VPN. Overlay networks can run across all or a subset of the underlay network devices. Multiple overlay networks can run across the same underlay network to support multitenancy through virtualization.
Cisco SD-Access Underlay
Key requirements:
IP reached from edge to edge, border, control plane
Can be Layer 2 or Layer 3 (Layer 3 recommended)
Can be any interior gateway protocol (IGP) (Intermediate System-to-Intermediate System [IS-IS] is recommended for scalability and integration with Cisco DNA Center)
Key considerations:
Maximum transmission unit (MTU) (fabric header adds 50 bytes)
Latency (round-trip time [RTT] of </= 100ms)
Automated underlay is fully automated and is providing global and IP underlay provisioning:
Key requirements:
Uses standard PnP for bootstrap
Assumes a new or erased configuration
Uses a global “underlay” address pool
Key considerations:
PnP pre-setup is required
100 percent prescriptive (not custom)
The following components make up the Cisco SD-Access solution:
Cisco DNA Automation: It provides simple GUI management and intent-based automation (for example, Network Control Platform [NCP]) and context sharing.
Cisco DNA Assurance: Data collectors (for example, Neighbor Discovery Protocol [NDP]) analyze endpoint-to-application flows and monitor fabric status Identity Services: Network Admission Control (NAC) and ID systems, for example, Cisco Identity Services Engine (ISE) for dynamic endpoint-to-group mapping and policy definition Control Plane Nodes: Map system that manages endpoint-to-device relationships Fabric Border Nodes: A fabric device (for example, Core) that connects the external Layer 3 networks to the SD-Access fabric Fabric Edge Nodes: A fabric device (for example access or distribution) that connects wired endpoints to the SD-Access fabric Fabric Wireless Controller: A fabric device (wireless LAN controller [WLC]) that connects APs and wireless endpoints to the SD-Access fabric.
