Ethernet vs. SDH
Ethernet refers to a family unit of computer networking technologies that is frame based. It is basically aimed for application in the local area networks or LANs. Ethernet, the very name comes in from the concept of the physical state of ether. Ethernet comprises of a number of signaling and wiring standards used with the Physical layer of the OSI model for networking via a network access at MAC (Media ACCESS Control) of the Data Link Layer. On the other hand, Synchronous Digital Hierarchy or SDH refers to a standardized multiplexing protocol that is capable of transferring multiple streams of digital bit above an optical fiber with the use of light emitting diodes or lasers. The lower rates in the SDH are transported by means of an electrical interface.
The very concept of the Ethernet which is a pioneering combination of the warped pair series of Ethernet was developed in order to connect the network and the end systems together with the fiber optic versions used to support the site backbones. In fact this technology is one the most extensive wired LAN technology till date. On the contrary the method of SDH was developed in order to reinstate the Plesiochronous Digital Hierarchy (PDH) system so that a superior quantity of telephone calls in addition to data traffic can be transferred through the same fiber wire devoid of any synchronization problems.
As far as the factor of redundancy protection is concerned, Ethernet is a fast spanning tree ranging from 10ms to 1s on the basis of the network topology; with link aggregation and a resellent packet ring of <50 ms and a MPLS fast reroute. On the other hand the SDH characterizes an automatic protection switching capability of 50ms. It has a link capacity adjustment scheme for the purpose of virtual concatenation.
Now coming to the issue of fault detection, Ethernet is capable of detecting remote link failure and can also remote monitor using the proprietary thresholds. On the other hand, SDH is capable of detecting sectionalized errors or defects through remote indications. It is also capable of threshold crossing and fault surveillance through performance monitoring.
Summary:
1)Ethernet is a frame based computer networking technology, SDH is a standardized multiplexing protocol.
2)Ethernet is a fast spanning tree ranging from 10ms to 1s whereas SDH characterizes an automatic protection switching capability of 50ms.
3)Ethernet can detect remote link failures whereas SDH is capable of detecting sectionalized errors or defects only.