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Using Physical Network Functions in Contrail Service Chains

Contrail Release 3.0 and greater supports service appliance-based physical network functions devices (PNFs) in service chains, enabling the creation of service chains that include a combination of virtual network functions (VNFs) and PNFs. The PNFs are also supported with Contrail Device Manager.

PNF Service Chaining Objects

As of Contrail Release 3.0, Contrail has objects used to support PNFs in service chains, including:

  • service appliance (SA)—represents a single physical appliance

  • service appliance set (SA set)—represents a collection of functionally equivalent SAs, all running the same software with the same capabilities

A service appliance is associated with a physical router that has physical interfaces for the left, right, management, or other interfaces.

There can be more than one service appliance and associated physical router and physical interface objects representing it.

A physical appliance can host more than one service appliance through a logical system or other virtualization capability.

The service template object supports a physical network function service template (PNF-ST). The PNF-ST is associated with a service appliance set, which represents a pool of service appliances that can be used when the PNF-ST is instantiated.

Only the transparent service mode is supported for PNF-STs.

Prerequisites and Assumptions

The following are the prerequisites for implementing a service appliance with a Contrail controller.

  • Before the controller can use a PNF SA, the controller must be connected to a service control gateway (SCG) router, such as an MX Series router.

  • The Contrail Device Manager must manage the SCG router.

  • The PNF SA must be configured, and it must be configured to operate as an Ethernet bridge. The Contrail controller does not automatically implement PNF SA configuration.

  • Infrastructure interfaces (physical interfaces or aggregated Ethernet interfaces) on the SCG facing the SA must be preconfigured. The interfaces must be able to support VLAN-based units.

  • Layer 2 VPNs as supported by the Contrail Device Manager are only available with Juniper Networks Junos Release 14.2R4 or greater. If an earlier version of Junos is used, you must mark the virtual networks in Contrail with the forwarding mode “L3 only.”

  • Logical interfaces for connecting the service gateway VRFs to the customer and the Internet must be preconfigured.