ns in Software-Defined Networks This is a straightforward and powerful approach which help us to virtualize services into a generic data center fabric. These services can be executed on standard computer and storage. It facilitates easy addition and removal of service just by including VMs and pushing the stack of labels accordingly at the network entrance. At last, it also enables us to scale services by spinning VMs and using a scale out rather than scaling up by principles. Moreover, the concept of service chaining should not assume always that the service elements would be located in a data center (or that all the service elements are virtualized), even though that can be a long-term goal of service providers for their edge/access deployments. It may be possible that services may get associated with network boundaries, for e.g. a security policy can be attached to the network boundary or a load balancer can be inserted at a network boundary. The figure describes network boundary, which can be: The borderline separating a tenant network from an external network (such as the Internet or the VPN to the enterprise network) The borderline that separate one tenant network from other tenant from different networks. The boundary that separate multiple networks of the same tenant Here, moving of a network functions into software results that building a service chain won't require acquiring hardware anymore. Figure 9. Multiple Network Functions Over Framework Tenant Network A Internet Tenant Tenant Network A Network B Tenant Tenant Network A1 Network A2 Downloaded 4/15/2022 9:44:49 AM Nova Southeastern University IP Address: 137.52.76.29 Virtualizing Network Functions in Software-Defined Networks Metadata Metadata can be used in sharing information about user's traffic with network functions making up a processing path and is important to service chaining concept. The standardization of the overlay encapsulation and the traffic matching protocol(s) used in creating service chains/paths raises a number of queries which 