NETWORK coding encourages information flows to be encoded within a data network, besides merely being forwarded and replicated. Such a departure from the classic store-and-forward principle has proven effective in increasing the network capacity. Bounding the Advantage of Multicast Network Coding in General Network Models Higher end-to-end throughput, particularly for multicast data transmission, is witnessed in a number of network scenarios . Multicast represents an increasingly more important class of applications on the Internet, encompassing traditional and emerging one-to-many data dissemination applications, such as software patch distribution, Bounding the Advantage of Multicast Network Coding in General Network Models live media streaming and video conferencing. fundamental problem in network coding is to quantify the benefits of network coding over routing, known as the coding advantage, measured as the ratio of the achievable throughput with network coding over that with routing. Bounding the Advantage of Multicast Network Coding in General Network Models Without network coding, a multicast routing solution is based on a multicast tree, or packing a set of multicast trees . In the directed network setting where each link has a predefined direction, there exists a combination network pattern where the coding advantage is unbounded as the network size grows . However, in the undirected network setting, Bounding the Advantage of Multicast Network Coding in General Network Models where capacity at each link can be shared flexibly between the two directions, a contrasting result was proved: the coding advantage is upper-bounded by a constant of. Directed and undirected graphs are classic subjects of study in theoretical computer science. While simple and easy to apply, they do not faithfully depict the wireline or wireless network topologies in practice. For example, large coding advantages in the directed setting are observed in contrived, extremely asymmetric topologies that favors network coding over tree packing, with links existing in one direction only Bounding the Advantage of Multicast Network Coding in General Network Models between neighboring nodes. This is apparently different from the picture of the Internet, where pair-wise router interconnections are mostly bidirectional, i.e., if a router A can transmit to a neighbor router B, so can B transmit to A. Bounding the Advantage of Multicast Network Coding in General Network Models This work studies the coding advantage in two types of parameterized networks with richer modeling power. The first is the bidirected network model, parameterized with α, the highest ratio of opposite link capacities between neighboring nodes.