SONET和SDH的区别

1.同步光网络(SONET)：
SONET 代表同步光网络。它是一种通信协议，由 Bellcore 开发，用于使用光纤在相对较大的距离上传输大量数据。通过 SONET，多个数字数据流通过光纤同时传输。

2. 同步数字体系(SDH)：
SDH 代表同步数字体系，它定义为电信中使用的多路复用技术。国际上使用的是同步光网络。据说它是 SONET 的一个变种，被认为等同于 SDH。它的特性建立在高阶复用之上。与代表 Plesiochronous Digital Hierarchy 的 PDH 相比，这些技术提供了相当快且价格低廉的网络互连。

SONET和SDH的区别：

S.No.	SONET	SDH
1.	SONET stands for Synchronous Optical Network.	SDH stands for Synchronous Digital Hierarchy.
2.	It is a digital hierarchy interface for the optical transmission.	It is a network node interface, user-network interface and U reference-point interface to assist BISDN.
3.	It is developed by ANSI (American National Standards Institute).	It is developed by ITU-T (International Telecommunication Union – Telecommunication Standardization Sector).
4.	It has total number of transport overhead of 9×3 = 27 bytes.	It has total number of transport overhead of 9×9 = 81 bytes.
5.	It can transmit data in only synchronous mode.	It can transmit in both synchronous mode and asynchronous mode.
6.	It does not provides better transmission rates as compared to SDH.	It provides better transmission rates as compared to SONET.