Fiber Optic Wiki

Comparison of MPLS versus ATM

August 8, 2011

While the underlying protocols and technologies are different, both MPLS and ATM provide a connection-oriented service for transporting data across computer networks. In both technologies, connections are signaled between endpoints, connection state is maintained at each node in the path, and encapsulation techniques are used to carry data across the connection. Excluding differences in the signaling protocols (RSVP/LDP for MPLS and PNNI:Private Network-to-Network Interface for ATM) there still remain significant differences in the behavior of the technologies.

Comparison of MPLS versus Frame

August 8, 2011

RelayFrame relay aimed to make more efficient use of existing physical resources, which allow for the underprovisioning of data services by telecommunications companies (telcos) to their customers, as clients were unlikely to be utilizing a data service 100 percent of the time. In more recent years, frame relay has acquired a bad reputation in some markets because of excessive bandwidth overbooking by these telcos.

MPLS local protection

August 8, 2011

In the event of a network element failure when recovery mechanisms are employed at the IP layer, restoration may take several seconds which may be unacceptable for real-time applications such as VoIP. In contrast, MPLS local protection meets the requirements of real-time applications with recovery times comparable to those of SONET rings of less than 50 ms.

The reliability and quality of an OTDR

August 6, 2011

The reliability and quality of an OTDR should be determined on the basis of its accuracy, measurement range, ability to resolve and measure closely spaced events, the speed at which it makes measurements, and its ability to perform satisfactorily under various environmental extremes and after various types of physical abuses. In addition to its cost, the instrument should also be rated on the features provided, its size, its weight, and how simple it is to operate.

The system x86 BIOS size limitations

August 5, 2011

Initially the size of an ATA drive, then called "IDE" was stored in the system x86 BIOS using a a type number 1 - 45 that predefined the C/H/S parameters. and often the landing zone as well. Which decides where to park the drive heads. Later a "user definable" format called C/H/S or cylinders, heads, sectors were made available. These numbers were important for the earlier ST-506 interface, but were generally meaningless for ATA -- the CHS parameters for later ATA large drives often specified impossibly high numbers of heads or sectors that did not actually define the internal physical layout of the drive at all. From the start and up to ATA-2 every user had to specify explicitly how large every attached drive was. From ATA-2 an "identify drive" command were implemented that can be sent and which will return all drive parameters.