Facilitating flow symmetry for service chains in a computer network

A method comprising:

• receiving, by a network controller for a virtualized computing infrastructure, a request for a service chain comprising one or more service instances for the service chain;
• installing, by the network controller to a server of the virtualized computing infrastructure, an egress service instance of the one or more service instances for the service chain;
• installing, by the network controller, the one or more service instances for the service chain to one or more servers of the virtualized computing infrastructure, the one or more service instances including the egress service instance;
• installing, by the network controller to a scalable service platform comprising one or more virtual routers executing on a set of one or more servers, to a first server of the one or more servers of the scalable service platform, a first service instance for an ingress of the service chain;
• installing, by the network controller to a second server of the one or more servers of the scalable service platform, a second service instance for an egress of the service chain, wherein the first service instance and the second service instance operate as endpoints for the service chain to anchor packet flows mapped to the service chain,
• wherein the second service instance is configured to receive a packet for a forward packet flow from the server hosting the egress service instance, wherein the packet comprises an outer Internet Protocol (IP) header comprising an IP address of the server hosting the egress service instance;
• creating, in response to receiving the packet for the forward packet flow and based on the outer IP header of the packet for the forward packet flow, a flow table entry for a reverse packet flow corresponding to the forward packet flow, wherein the flow table entry specifies the IP address of the server hosting the egress service instance as a next hop for the reverse packet flow;
• and
• forwarding, by the second service instance and based on the flow table entry, the reverse packet flow to the server hosting the egress service instance.

A network controller for a virtualized computing infrastructure, the network controller comprising processing circuitry coupled to a memory device, wherein the network controller is configured to:

• receive a request for a service chain comprising one or more service instances for the service chain;
• install, to a server of the virtualized computing infrastructure, an egress service instance of the one or more service instances for the service chain;
• install the one or more service instances for the service chain to one or more servers of the virtualized computing infrastructure, the one or more service instances including the egress service instance;
• install, to a server of a scalable service platform comprising one or more virtual routers executing on a set of one or more servers, to a first server of the one or more servers of the scalable service platform, a first service instance for an ingress of the service chain;
• install, to the server of the scalable service platform, a second service instance for an egress of the service chain, wherein the first service instance and second service instance operate on the server as endpoints for the service chain to anchor packet flows mapped to the service chain,
• wherein the second service instance is configured to receive a packet for a forward packet flow from the server hosting the egress service instance, wherein the packet comprises an outer Internet Protocol (IP) header comprising an IP address of the server hosting the egress service instance;
• create, in response to receiving the packet for the forward packet flow and based on the outer IP header of the packet for the forward packet flow, a flow table entry for a reverse packet flow corresponding to the forward packet flow, wherein the flow table entry specifies the IP address of the server hosting the egress service instance as a next hop for the reverse packet flow and
• forward, by the second service instance and based on the flow table entry, the reverse packet flow to the server hosting the egress service instance.