What does "local link" mean? The context is parallel computing architectures

Also, how do you do part a and b?

Table 4.2. Topological Parameters of Selected Interconnection Networks Network diameter Network name(s) ID mesh (linear array) 1D tours (ring, loop) 2D mesh 2D torus (k-ary 2-cube) 3D mesh 3D torus (k-ary 3-cube k Pyramid Binary tree 4-ary hypertree Butterfly Hypercube Cube-connected cvcles Shuffle-exchange De Bruijn No. of nodes Bisection width Node degree Local links? Yes Yes Yes Yes Yes Yes 2k-2 2k 3k- 3 3k/2 2k 2k (4k )/32log2 k 21-2 0 0 0 0 0 0 2'(2+1-1) 2 (1+1) 21 21- 1 4 unidir. 4 unidir. With folded layout Table 4.2. Topological Parameters of Selected Interconnection Networks Network diameter Network name(s) ID mesh (linear array) 1D tours (ring, loop) 2D mesh 2D torus (k-ary 2-cube) 3D mesh 3D torus (k-ary 3-cube k Pyramid Binary tree 4-ary hypertree Butterfly Hypercube Cube-connected cvcles Shuffle-exchange De Bruijn No. of nodes Bisection width Node degree Local links? Yes Yes Yes Yes Yes Yes 2k-2 2k 3k- 3 3k/2 2k 2k (4k )/32log2 k 21-2 0 0 0 0 0 0 2'(2+1-1) 2 (1+1) 21 21- 1 4 unidir. 4 unidir. With folded layout