Dear friend!
In a transport network, there are usually several distance levels:
1. Intra-office transmission and intra-site optical cable connection: about 0 km to 2 km
2. Short-distance transmission, about 2 to 40 km.
3. Long-distance transmission, about 40 to 100 km
4. Ultra-long-haul(ULH) transmission, more than 100 km.
Please note that there are no clear boundaries between the above categories.
Thanks!