Provisioning Overlay Networks Using Cisco Virtual Topology System
Virtual Topology System enables overlay connectivity orchestrated through an SDN-based control plane. This ensures instant availability of computing and application workloads in the virtualized data center, and removes network provisioning challenges.
Cisco VTS uses VXLAN to overcome scale limits in the data center and to segment the network better. VXLAN is designed to provide the same Ethernet Layer 2 network services as VLAN does, but with greater extensibility and flexibility. The dependence on a Layer 3 underlay network allows VXLAN to take complete advantage of Layer 3 routing, equal-cost multipath (ECMP) routing, and link aggregation protocols. Virtual Topology System supports hardware and software VTEPs to segment the data center network.
Virtual Topology System supports both VXLAN overlays using the BGP EVPN control plane and VXLAN overlays using IP Multicast-based techniques.
Implementing VXLANs using MP-BGP EVPN based control plane to manage the VXLAN overlay provides a distributed network database, which enables federation and scaling. The BGP EVPN solution is the preferred option, and it can be flexibly implemented using the infrastructure policy constructs within the Virtual Topology System environment.
Virtual Topology System implements the highly scalable MP-BGP with the standards-based EVPN address family as the overlay control plane to:
Distribute attached host MAC and IP addresses and avoid the need for unknown unicast, and multicast traffic
Support multi-destination traffic by either using the multicast capabilities of the underlay or using unicast ingress replication over a unicast network core (without multicast) for forwarding Layer 2 multicast and broadcast packets
Terminate Address Resolution Protocol (ARP) requests early
Control-plane separation is also maintained among the interconnected VXLAN networks. Capabilities such as route filtering and route reflection can be used to provide flexibility and scalability in deployment.
High-level Workflow for Establishing a VXLAN Overlay Network with Hardware and Software VTEPs using BGP EVPN
The following steps provide a high-level workflow for establishing a simple VXLAN overlay network with hardware and software VTEPs using a BGP EVPN control plane:
Prepare the physical environment to be managed by Cisco VTS to build virtual overlays. See the Prerequisites section in the Cisco VTS Installation Guide for details.
- Discover the network topology in the data center. See the Managing Inventory chapter of the Cisco VTS User Guide for details.
- Define Admin Domains. See Creating and Managing Admin Domains chapter of the Cisco VTS User Guide for details.
After you commit the changes to the network group, Virtual Topology System automatically pushes all the relevant configuration information to the respective leafs, VTSR, and DCI gateways. At this point, the Admin Domain is ready to build overlay networks based on the intent defined by the service policy or through a Virtual Machine Manager (VMM) or orchestration environment.
Cisco VTS supports dual stack IPv4 and IPv6 addressing for overlay provisioning.
For a detailed, illustrated example, see Cisco Virtual Topology System: Data Center Automation for Next-Generation Cloud Architectures White Paper.