Question: 1 stm how many e1?
Answer: STM-1 (155Mb/s) is 63 x E1, STM-4 (622Mb/s) is 4 x STM-1 and STM-16 (2.5Gb/s) is 4 x STM-4. The benefits of SDH are: Different interfaces or different bandwidths can connect (G708, G781).