Friday, September 18, 2009


Today, the optical fiber is widely used in France, Europe and in the world. In France and Europe, we can mention the network that LDCOM comprises 11,000 km of fiber connecting 60 cities. By using WDM and SDH, it and can reach speeds of several hundreds of Gbit / s. Extended ends by MAN, the network now extends Spain, Italy and Switzerland. At the global level, the intercontinental routes are in perpetual changes to withstand the ever-changing traffic. Today, the recent work of the CNET (National Center for Studies in Telecommunications) on the show that soliton transmission can be push the limits inter-amplifiers. A soliton a very short light pulse which propagates without remarkable deformation of its shape or change its speed. This phenomenon has been noticed for the first time as a wave in a channel, but it exists in many fields, including light. Thus, one can use a very wide bandwidth with transmission speeds Agenda p├ętrabit per second or one million gigabit per second. The pulse modulation is based on the coding of the pulse corresponding to a logic with two or three levels. This technology has been used by MCI-WorldCom, which reached a speed 10 Gbit / s over 900 kilometers and CNET, in March 1999, which transferred data at a rate greater than one terabit per second  1000 km via a conventional optical fiber. The fiber seems to be the medium of the future in the relationship long distances.

Sunday, September 6, 2009

The use of SONET and WDM

Today, the use of SONET and WDM multiply. Indeed, coupled use of these two technologies yields networks Optical integrating the strengths of SDH: transmission reliability and management bandwidth. These networks are currently expanding throughout the world and examples are more numerous

However, researchers are trying to reduce the stack
protocols used to arrive in all-optical solutions. Could
then see soon arrive networks constructed as follows:

Researchers are also set for challenge to achieve the "Optical
buffer "or other words to store the light ...

The return of alarms

SDH allows the sky to achieve the alarm on the various equipment. These alarms correspond to different problems could exist on the equipment or connections.
Major alarms are:
• AU-AIS (Administrative Unit Alarm Indication Signal)
• AU-LOP (Administrative Unit Loss of Pointer)
• HP-UNEQ (HO Path Unequipped)
• HP-RDI (HO Path Remote Defect Indication)
• LOF (Loss of Frame) Frame Loss
• LOS (Loss of Signal, drop in incoming optical power level
causes high bit error rate.) Loss of signal
• LOP (Loss of Pointer) Loss of Pointer
• LP-UNEQ (LO Path Unequipped)
Johann COPIN
Eric Panetta IR3 - 2003
• MS-AIS (Multiplex Section Alarm Indication Signal)
• MS-REI (Multiplex Section Remote Error Indication)
• MS-RDI (Multiplex Section Remote Defect Indication)
• OOF (Out of Frame)
• TU-AIS (Tributary Unit Alarm Indication Signal)
• TU-LOM (Loss of Multiframe)

Wednesday, September 2, 2009

Equipments of SDH connections

Major equipment
There are 4 main categories of equipment to make connections SDH:

Switch card: This card provides the functions of multiplexing and circulating traffic between line interfaces and other interfaces. Its capacity is equivalent to 12x12 STM - 1, without limitation ( "non-blocking matrix"). This card can be split to ensure protection.

The line cards (STM-1, 4.16 ..): These cards provide optical transmission signals STM. They are not split. The failure of one of them does not the protected traffic as it is transmitted simultaneously interfaces on the "East" and "West".

The multiplex controller module: this card provides the functions of central control and safeguard the configuration. It is not split because its failure does
not disrupt traffic.

The communication card: This card provides the functions management to network management. It is routed through the signal STM online. This map is not split because its failure does not disrupt the traffic.

Tuesday, September 1, 2009

The SONET frame and security

The SONET frame is composed of 9 rows. The first three bytes of each row contain information synchronization and supervision. Similar to SDH, we find the principle of adaptation-related encapsulation of data in virtual containers


Different techniques can secure the use of SONET / SDH; these techniques are mainly access control and encryption, conventional solutions. Cons attacks format by inserting data specifically constructed, jamming is an excellent technique, at least in theory.

However, SONET and SDH are nevertheless sensitive to some uses flawed, as the inclusion of escape sequences. Has priori, these limits are not really security problems
Major: they can cause denial of service on the network, and degradation of the service should not be significant (depending In reality, the type of connection available to the attacker). In conclusion of this it is said that using SDH and SONET safely is realistic, complex attacks to work is very high.