The Resource Pod networking is highly dependent on the network topology that is required by the telco workloads, which tenants deploy. Telco workloads require a certain set of networking building blocks.
Segments
Segments are the layer 2 networks created by NSX-T Data Center to provide connectivity between its services and the VMs. Segments form the basis of the tenant networks in the Telco Cloud Infrastructure platform. The primary component in the data plane of the transport nodes is the N-VDS. The N-VDS forwards traffic between components running on the transport node (that is between VMs) or between VMs and the physical network. In the latter case, the N-VDS must own one or more physical interfaces (physical NICs) on the transport node. As with other virtual switches, an N-VDS cannot share a physical interface with another virtual switch. Additional N-VDSs can be created by using a separate set of physical NICs.
Logical Routing
The NSX-T Data Center platform provides the ability to interconnect both virtual and physical workloads that are deployed in different logical layer 2 networks. NSX-T enables the creation of network elements such as segments and gateways as software logical constructs, abstracted from the underlying physical hardware.
East-West Traffic
Configuring a gateway through the NSX Manager instantiates a gateway on each hypervisor. For the VNFs hosted on the same hypervisor, the East-West traffic does not leave the hypervisor for routing. The gateway is also responsible for routing East-West traffic between hypervisors. The org VDC of the Telco Cloud Infrastructure platform deploys and manages the Tier-1 gateway for routing services between their respective org VDC networks within their tenancy.
North-South Traffic
In addition to providing optimized distributed and centralized routing functions, NSX-T Data Center supports a multi-tiered routing model with a logical separation between the provider routing function and the tenant routing function. This way, the concept of multitenancy is built in the routing model. The top-tier logical router is called a Tier-0 gateway, whereas the bottom-tier logical router is called a Tier-1 gateway. Northbound, the Tier-0 logical gateway connects to one or more physical routers or layer 3 switches and serves as an on/off-ramp to the physical infrastructure. Southbound, the Tier-0 gateway connects to one or more Tier-1 gateways.
This model also eliminates the dependency on a physical infrastructure administrator to configure or change anything on the physical infrastructure when a new tenant is configured in the data center. For a new tenant, the Tier-0 gateway simply advertises the new tenant routes that are learned from the tenant Tier-1 gateways on the established routing adjacency with the physical infrastructure.
