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Evolution of technology

Submitted by on Wednesday, 19 June 2013No Comment

Attempts at the construction stack мультисервисных IP networks with QOS, and the emergence of technology to increase the capacity of physical infrastructure of data transmission (DWDM for the xDSL and fiber to copper), led to the evolution of technology itself switching IP-packets. Go to any Internet network is not reached such a level without having to not collapse under the weight of complex architectural issues. Long overdue modernization IPv4 and IPv6 stack new version corresponds to the set of systemic issues. But the emergence of IPv6 was not a revolutionary leap – mass conversion to the new version was not.
Internet demonstrates the flexibility and ability to evolve, while maintaining continuity of applications. Technology, address specific problems that developed in the framework, leading to changes in the overall architecture of communication networks at the system level. One of these technologies – MPLS – technology multyprotokolnoy switching point.

MPLS originally designed for solving problems of optimization of IP routing in ATM networks and accelerate the lookup routing table on the receiver. The principle of isolation from the IP-stack and channel physical layer of the OSI model makes it easy to carry IP-application on any physical medium of transmission, but causes several problems routing efficiency. If the IP-network based on switched virtual connections in ATM-OBLAKE, then the denial of one of the compounds originally held at the convergence of ATM, and then start IP-converged network.
This fundamental problem, because at ATM can be on routing decisions that conflict with the decisions taken at the level of IP. Suppose there OBLAKE ATM-overload one or more switches, which affected the service quality of virtual connections. IP level this concept has, therefore, question of priority routing IP-packets with a given quality of service can not be.

Solving these problems, developers have offered separate MPLS control and switching components routing traffic and also introduce a fixed packet identifier – a label. Tag is a fixed-length header that identifies the set of packets transmitted in some way (eg, same recipient or as a class of service). Tag is local to the switch value, ie not to.

The control component architecture includes a third level of routing protocol model OSI (in this case IP OSPF or IS-IS), which works with the procedures agreed allocation and distribution point. It performs well-directed set of values along the path switching routing information according to IP (or other protocol). These functions are implemented through well-directed distribution protocol (LDP).

After all of the ATM is gradually forgotten and began to develop new technology features such as a new concept of virtual private network (VPN) technology and traffic flow management in transmission networks (Traffic Engineering). The latter are directly related to the problem of quality of service in IP-networks.

Routing protocols in IP-based networks of Dijkstra’s algorithm – shortest path algorithm to connected graphs (SPF-protocols such as OSPF, IS-IS). All routers are building the shortest path tree to other nodes. Route tables are built based on the tree.

Source: voipfone.ru