The Edge Pod components provide the fabric for North-South connectivity to the provider networks. Multiple configurations can be used for performance, scale, and Edge services.
Edge Nodes
An Edge Node is the appliance that provides connectivity between the physical and virtual infrastructures. Edge Nodes serve as pools of capacity, dedicated to running network services that cannot be distributed to the hypervisors. The network functionalities of the Edge node include:
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Connectivity to the physical infrastructure (Routing).
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Edge services such as NAT, DHCP, firewall, and load balancer.
Edge nodes are available in two form-factors: VM and bare metal. Both leverage DPDK for faster packet processing and high performance. Depending on the use case, the appropriate form-factor is deployed.
The NSX bare metal Edge runs on a physical server and is installed by using an ISO file or PXE boot. The bare metal Edge is recommended for production environments where services such as NAT, firewall, and load balancer are required in addition to Layer 3 unicast forwarding. A bare metal Edge differs from the VM form-factor Edge in terms of performance. It provides sub-second convergence, faster failover, and throughput greater than 10 Gbps.
The VM form-factor of NSX Edge is installed by using an OVA, OVF, or ISO file. Depending on the required functionality, there are deployment-specific VM form-factors.
Edge Clusters
Edge nodes are deployed as pools of capacity (a cluster), dedicated to running network services that cannot be distributed to the hypervisors. An Edge cluster can either be all VM or all bare metal form-factors.
The Edge cluster provides scale-out, redundant, and high-throughput gateway functionality for logical networks. Scale-out from the logical networks to the Edge nodes is achieved by using ECMP. There is total flexibility in assigning gateways to any specific clusters. Tier-0 and Tier-1 gateways can be hosted on either the same or different Edge clusters.
There can be only one Tier-0 gateway per Edge node, however, multiple Tier-1 gateways can be hosted on one Edge node.
In addition to providing distributed routing capabilities, the Еdge cluster enables Еdge services at a provider or tenant scope. As soon as one of these Еdge services is configured or an uplink is defined on the gateways to connect to the physical infrastructure, a Service Router (SR) is instantiated on the Edge Node. Similar to the compute nodes in NSX-T Data Center, the Edge Node is also a transport node and it can connect to more than one transport zone: one for overlay and another for N-S peering with external devices.
A maximum of 10 Edge Nodes can be grouped in an Edge cluster, although only eight can be used for ECMP routing. A Tier-0 gateway supports a maximum of eight equal-cost paths, thus a maximum of eight Edge Nodes are supported for ECMP. Edge Nodes in an Edge cluster run Bidirectional Forwarding Detection (BFD) on both tunnel and management networks to detect the Edge Node failure. The BFD protocol provides fast detection of failure for forwarding paths or forwarding engines, improving convergence. Bare metal form factors can support sub-second convergence.
NSX-T Data Center supports static routing and the dynamic routing protocol BGP on Tier-0 gateways on interfaces connecting to upstream routers. Tier-1 gateways support static routes but do not support any dynamic routing protocols.
For more information, see the VMware® NSX-T Reference Design Guide.
