h = {('R1', 'Eth0/0'): ('SW1', 'Eth0/1'),
 ('R2', 'Eth0/0'): ('SW1', 'Eth0/2'),
 ('R2', 'Eth0/1'): ('SW2', 'Eth0/11'),
 ('R3', 'Eth0/0'): ('SW1', 'Eth0/3'),
 ('R3', 'Eth0/1'): ('R4', 'Eth0/0'),
 ('R3', 'Eth0/2'): ('R5', 'Eth0/0')}

sps_l_o_l = [[k,v] for k,v in h.items()]
sps_l = []
for k,v in h.items():
    sps_l.append (k)
    sps_l.append (v)
sps_l_2nd_approach = [val for inner_sps in sps_l_o_l for val in inner_sps]
sps_l_o_t = [(k,v,) for k,v in h.items()]

print (sps_l_o_l)
print (sps_l)
print (sps_l_2nd_approach)
print (sps_l_o_t)