1. Beijing University of Posts and Telecommunications, State Key Laboratory of Networking and Switching Technology, 554993 Beijing, Beijing, China, 100876 (e-mail: fenglei@bupt.edu.cn)
2. State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, 12472 Beijing, Beijing, China, (e-mail: 2019111415@bupt.cn)
3. State Key Laboratory of Networking and switching technology, Beijing University of Posts and Telecommunications, 12472 Beijing, Beijing, China, 100088 (e-mail: syguo@bupt.edu.cn)
4. the State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, Beijing, Beijing, China, (e-mail: xsqiu@bupt.edu.cn)
5. State Key Laboratory of Networking and Switching Technology, Beijing University of Posts and Telecommunications, 12472 Beijing, Beijing, China, (e-mail: wjli@bupt.edu.cn)
6. Computer institution, Beijing University of Posts and Telecommunications, 12472 Beijing, Beijing, China, (e-mail: yupeng@bupt.edu.cn)