Difference between Underlay Network and Overlay Network
IT industry is making great strides towards efficiency and scalability to meet the virtualization demand. The key ask is for the demand of multitenancy and virtualization features like VM mobility as turnkey projects.
Related – HLD and LLD
Network Overlays –
Network overlays is the latest solution to meet these demands, in fact, this technology can speed configuration of new or existing services.
Underlay Network –
Underlay Network is different from Underlay Network which IT industry has known for years. Underlay Network is physical infrastructure above which overlay network is built. It is the underlying network responsible for delivery of packets across networks.
Overlay Network –
An Overlay Network is a virtual network that is built on top of underlying network infrastructure (Underlay Network). Actually, “Underlay” provides a “service” to the overlay
Below table enumerates the difference between Underlay Network and Overlay Network:
|PARAMETER||UNDERLAY NETWORK||OVERLAY NETWORK
|Philosophy||Underlay Network is physical infrastructure above which overlay network is built.||An Overlay network is a virtual network that is built on top of an underlying Network infrastructure/Network layer (the underlay).
|Related protocols||Ethernet Switching, VLAN , Routing etc.||VXLAN , OTV , VPLS
|Scalability||Less Scalable due to technology limitation||Designed to provide more scalability than underlay network. For e.g. – VXLAN (underlay Network) provides 4096 Vlan support while VXLAN (Overlay Network) provides upto 16 million identifiers.
|Packet control||Hardware orchestered||Software orchestered
|Packet delivery||Responsible for delivery of packets||Offloaded from delivery of packets
|Packet encapsulation and overhead||Packet delivery and reliability occurs at layer 3 and Layer 4 ||Needs to encapsulate packets across source and destination, hence incurs additional overhead.
|Managing multitenancy||NAT or VRF based segregation required which may face challenge in big environments||Ability to manage overlapping IP addresses between multiple tenants.
|Multipath forwarding||Less scalable options of multipath forwarding. Infact using multiple paths can have associated overhead and complexity.||Support for multi-path forwarding within virtual networks.
|Deployment time||Less scalable and time consuming activity to setup new services and functions||Ability to rapidly and incrementally deploy new functions through edge-centric innovations
|Traffic flow||Transmits packets which traverse over network devices like Switches and Routers.||Transmits packets only along the virtual links between the overlay nodes.
Download the difference table here.
Know more about Cloud Overlay network in this video :