2.1. Shared Service Functions

2.1.1. Description

This use case aims at binding multiple networks or network services to a single vNIC (port) of a given VM. There are several specific application scenarios for this use case:

  • Shared Service Functions: A service function connects to multiple (tenant) networks by means of a single vNIC.

    Typically, a vNIC is bound to a single (tenant) network. Hence, in order to directly connect a service function to multiple (tenant) networks at the same time, multiple vNICs are needed - each vNIC binding the service function to a separate network. For service functions requiring connectivity to a large number of networks, this approach does not scale as the number of vNICs per VM is limited and additional vNICs occupy additional resources on the hypervisor.

    A more scalable approach is to bind multiple networks to a single vNIC and let the service function, which is now shared among multiple networks, handle the separation of traffic itself.

  • Multiple network services: A service function connects to multiple different network types such as a L2 network, a L3(-VPN) network, a SFC domain or services such as DHCP, IPv6 NDP, firewall/security, etc.

In order to achieve a flexible binding of multiple services to vNICs, a logical separation between a vNIC (instance port) - that is, the entity that is used by the compute service as hand-off point between the network and the VM - and a service interface - that is, the interface a service binds to - is needed.

Furthermore, binding network services to service interfaces instead of to the vNIC directly enables a more dynamic management of the network connectivity of network functions as there is no need to add or remove vNICs.

2.1.2. Requirements

2.1.2.1. Northbound API

The API has to cover the following functionality:

  • management of instance ports
  • management of service ports
  • binding of services to service ports

2.1.2.2. Data models

TBD

2.1.2.3. Orchestration

None.

2.1.2.4. Dependencies on other resources

The compute service needs to be enabled to consume instance ports instead of classic Neutron ports.

2.1.3. Implementation Proposal

TBD