Access Network

ETHERNET
PDH
SDH

Ethernet technology has become much more advanced than local networks. It got rid of collisions, got full duplex and gigabytes of speed. Wider spectre of economically efficient decisions has allowed using Ethernet on main lines. Ethernet is a packet technology of computer networks. Ethernet standards define wire connections and electric signals on physical level, packet format and medium access control protocol on the channel level of the model OSI. Ethernet is mainly described by the standards IEEE 802.3. Based on some reasons, in addition to the main standard, a lot of producers recommend using other patented carriers. For example, in order to increase the distance between two points of a network, it is more reasonable to use fiver-optic cables. The majority of Ethernet-maps and other devices have support of some data rates. These devices use auto detection of speed and duplex in order to achieve the best connection. If auto detection does not perform properly, the speed adjusts accordingly, and the mode of half-duplex transmission switches on. For example, Ethernet hub 10/100 suggests that by using this it is possible to work based on the technologies such as 10BASE-T and 100BASE-TX. Also, Ethernet hub 10/100/1000 supports the standards, such as 10BASE-T, 100BASE-TX, and 100BASE-T.

 

Based on the existing infrastructure PDH, it often seems reasonable to provide the maximum amount of services by using proven working PDH technology. This technology is effective from the perspective of revenue and total cost. Certainly, all technologies eventually become obsolete, however, their replacement comes to life only when a new technology is able to provide the same services at a lower cost and risk. This means that PDH as well as many other mature technologies will be used in network communication for a while.

ComTel-NS is able to offer smooth transition from traditional networks TDM to Ethernet/IP networks.

SDH (synchronous digital hierarchy) technology was initially developed for connection and synchronic transmission of PDH through fibre-optic cables. This technology has become very common across the globe. It has qualities, such as large bandwidth, flexibility, ability to increase network capacity without traffic interruption, reliability, ability to add channels at every location of network, convenience in management and administration. These factors contributed to widespread use of SDH, including OTC. However, rapid development in information technologies and emergence of NGN resulted in drastic increase of corporate needs and industries with high-speed data transmission. The main difficulty in data transmission is that packet information should be packed into virtual containers of TDM traffic transmission. The most optimal decision was to create SDH networks of a new generation, which became called NGH SDH.  According to SDH standards requirements, protection-switching time from working direction to backup direction should not exceed 50 ms. Aggregate sum of these factors allows to minimize traffic losses in case of the line damage. It can also increase network uptime.