def METHOD_NAME(dut_t0_neigh, topo_config):
    vips_prefixes = []
    # find all vips prefixes
    for neigh in dut_t0_neigh:
        prefixes = topo_config[neigh]['vips']['ipv4']['prefixes']
        for prefix in prefixes:
            if prefix not in vips_prefixes:
                vips_prefixes.append(prefix)
    # use the first prefix for testing
    return vips_prefixes[0]