Datacenter Network Architecture

3 Tier 

• Core Layer is the high-speed, backbone of the network. These switches are used to forward traffic as quickly as possible between networks which are geographically separated.

• Distribution Layer is responsible for providing a boundary by implementing access control lists (ACLs) and other types of application filters and policies. The distribution layer is made up of layer 3 switches.

• Access Layer is used to interconnect end devices such as computers, printers and servers.

• Benefits of the Cisco 3 Layer Hierarchical designs are:

  • Improved Performance

  • Improved Management

  • Improved Scalability

  • Better Redundancy

Software-Defined Networking (SDN)

• In a network device such as a router or switch, each device is responsible for their own decisions and has three (3) planes:

  • Management Plane

  • Data Plane

  • Control Plane

Management Plane

• Controls the protocol that allows us to management the device, such as Telnet and SSH, SNMP, APIs.

Control Plane

• Controls the traffic in the device, such as OSPF (routing), ACLs, NAT, STP, CDP, LLDP

Data Plane

• Handles the sending, processing and receiving traffic 

Benefits of SDN

• In Controller-based networking, the Control plane is removed from the individual networking devices and a controller takes the responsibility of controlling all the network devices.

• The networking devices are managed by the controller, SDN controller via the Northbound Interface (NBI).

• The controller uses South Bound Interface (SBI) to manage the routers and switches, this exists between the Control Plane and Data Plane.

• The SDN controller can use OpenFlow, OpFlex, CLI/SNMP or NETCONF to control the routers and switches.

Overlay

• The Overlay is a virtual network tunnels over your underlay devices.

• Creates a direct link between devices, tunneled. - VXLAN - Virtual Extensible LAN.

• The SDN controller makes the tunnel happen.

Underlay

• The Underlay is a physical network that provides connectivity for the overlay.

• Creates layer 3 lanes using OSPF or EIGRP to ensure multiple paths

Fabric

• Fabric is everything the devices and components within the network, it’s the application, devices, overlay and underlay.

Spine-leaf

• The lower switches (leaf) are connected to the upper layer switches (spine) to create a full-mesh design. The lead layer is made up of access switches, each leaf switch is connected to every spine switch. 

• In a Spine-Leaf architectures uses VXLAN. Virtual Extensible LAN (VXLAN) is a network virtualization technology that attempts to address the scalability problems associated with large cloud computing deployments.