  Achievable degrees-of-freedom (DoF) of the large-scale interfering two-way
relay network is investigated. The network consists of $K$ pairs of
communication nodes (CNs) and $N$ relay nodes (RNs). It is assumed that $K\ll
N$ and each pair of CNs communicates with each other through one of the $N$
relay nodes without a direct link between them. Interference among RNs is also
considered. Assuming local channel state information (CSI) at each RN, a
distributed and opportunistic RN selection technique is proposed for the
following three promising relaying protocols: amplify--forward,
decode--forward, and compute--forward. As a main result, the asymptotically
achievable DoF is characterized as $N$ increases for the three relaying
protocols. In particular, a sufficient condition on $N$ required to achieve the
certain DoF of the network is analyzed. Through extensive simulations, it is
shown that the proposed RN selection techniques outperform conventional schemes
in terms of achievable rate even in practical communication scenarios. Note
that the proposed technique operates with a distributed manner and requires
only local CSI, leading to easy implementation for practical wireless systems.
