Method for establishing logical connections in a synchronous digital data communication network , network element and management system

The invention relates to a method for establishing logical Connections in a synchronous digital data transmission network according to claim 1 and a network element for a synchronous digital Message transmission network as claimed in claim 6 and a Management system of claim 8.

Data packets, for example, come from local area networks, are transmitted data networks to relevant addressees. Such data packets originating in particular applications of the Internet, are still the Internet Protocol (IP) set up and have a source and a destination IP address. The transmission medium (OSI Layer 1) for data networks in Wide-range data transmission are synchronous digital Communications networks used, in accordance with the SDH or SONET standards and recommendations work (SDH: Synchronous Digital Hierarchy, SONET: Synchronous Optical Network). This appears from eg RFC1619 (W. Simpson, Request for Comments 1619, Internet Engineering Task Force, Network Working Group, May 1994) shows where proposed is, for point-to-point connections, the data packets directly in synchronous Transport modules (STM-N) from SDH or synchronous transport signals (STS-N) from SONET to pack.

In synchronous digital communication networks, virtual, connected ie logical connections between network elements of the network will. This is manually by means of a management system made. The once switched logical connections then by routers of different data networks to access the producing synchronous digital data transmission network, to Transmission of data packets used.

Since in particular applications of the Internet in time greatly varying Datasets produce (between 0 bit / s and several Mbit / s), which in The form of IP data packets via the synchronous digital Communications network to be transmitted, there is the disadvantage that either large transmission capacity in the Communications network must be kept, then the most of the time remain unused, or that bottlenecks in transmission occur when multiple users send large amounts of data simultaneously want.

In another concept IP packets are first into ATM cells packed and then via virtual Übertragungungskanäle by synchronous digital communication network (SDH or SONET) transfer. . An article in the Fa Ipsilon Networks ( "IP Switching: The Intelligence of routing, the performance of switching ", Ipsilon Technical White Paper on IP Switching, Febuary 1996 available online at http://www.ipsilon.com/productinfo/wp-ipswitch.html) is a device (IP switch) presented which the function of an IP router and an ATM switch combined. It is capable of long sequences of data packets with the same source and destination address, so-called <i>flows,</i> by a identify device monitor and internal device for this appropriate for switching connections. Thereby, the throughput of data packets increased by the IP switch and shortens the average switching time. Here too there is the disadvantage that only fixed predetermined logical connections can be used, either company depending on the current load or are oversized.

In a theoretical article by LH Campell et al., "A Layered Approach to Network Management Control ", Proceedings of the Network Operations and Management Symposium, Nom, Memphis, 6th-9th April 1992 IEEE, Vol. 1, January 1, 1992, pages 46-56, is for managing an SDH network, a multi-layered approach proposed. A as Path Configuration sublayer designated management layer considers the Network as a plurality of logical connections between Network elements. In this management layer reconfigurations are the logical connections for the purpose of the bandwidth management performed. In another management layer, the Traffic Configuration sublayer is performed, the switching of calls. In this layer is also a monitoring and traffic statistics function executed. The article suggests that the monitoring results Traffic Configuration sublayer be used to optimize the perform existing logical connections. Since the network for heterogeneous services such as PSTN, ISDN and CCS is provided requires this proposal constitutes a communication between the different Switching equipment and the underlying transport network. As such communication should be like and how to monitor the heterogeneous services should look like, the article leaves open. In addition, requires the proposed unified management system for Switching equipment and network elements of the transmission network. On However, such a unified management system is not yet available.

The article by S. Kheradpi et al., "Performance Management in SONET-Based Multi-Service Networks ", Countdown to the New Millenium, Phoenix 2nd-5th December 1991, IEEE, Vol. 2, December 2, 1991, pages 1406-1411, discloses a method for real-time bandwidth management in a known SONET-based multi-service network. In the network using virtual containers (as virtual SONET Tributaries called) logical connections set up, the periodic are updated in order to optimize the connections. For this purpose, intelligent access units (Remote Unit) as a service access (Service Gateway) used include the incoming connections, and data (Source Destination arrival counts) and due to the counting Source / sink-bandwidth requirements (Source Destination bandwidth demands) Send to a central network management. The Network management updated to reflect the requirements of the existing logical connections regularly. The proposed Concept provides a unified management system for access node, Vermittlungsstelleh and network elements of the underlying Transport network (SONET) ago. In addition, intelligent access node for various services such as 64kbps language, broadband video signals, interactive graphics and multimedia needs that counts the perform and the bandwidth requirements for the network management send.

An object of the invention to provide a process by which a synchronous digital communication network to better time varying data traffic can be adapted. Other objects of the Invention are to provide a network element and a management system for provide a synchronous digital communication network, for Carrying out the method are suitable.

The object is in terms of the process achieved by the features of claim 1, with regard to the network element by the features Claim 6 and in terms of the management system by the features of claim 8.

One advantage of the invention is that existing transmission capacity at the transmission of data packets can be utilized better and that the transmission rate is higher on average than in the past. an additional Advantage is that commercially available IP routers are used can and that over for a user, the data packets that wants to send data transmission network, no changes to its are devices needed.

In a particularly advantageous embodiment, in addition, a Monitoring of sender addresses performed. This is a Charging for transmitted data packets possible.

According to a further advantageous embodiment of the invention is possible data packets with predetermined sender or destination addresses, For example, all data packets from or for a single, predetermined user, a higher priority in transmission grant.

In the following, an embodiment of the invention with reference to the 1 to 2b described. Show it:<dl tsize="8" compact="compact"><dt>figure 1</dt><dd>two over a synchronous digital communication network connected to local area networks (LANs),</dd><dt>figure 2a</dt><dd>a configuration of a data transmission network in high-traffic between adjacent users</dd><dt>figure 2b</dt><dd>a configuration of a data transmission network in high data traffic between remote users</dd></dl>

In Figure 1, two local area networks LAN1, LAN2 are shown, which via a synchronous digital communication network SDH together are connected and via the communication network data packets exchange. The access of data networks to the Transmission network SDH form Router RTR1, RTR2. These are each with a network element NE1, NE2 of Communications network connected. Between these two Network elements NE1, NE2, there is a logical connection through the SDH network are transported via the data to be transmitted packets. If data packets from the first local area network LAN1 to the second local area network LAN2 are transmitted, they will be in the first network element NE1 in synchronous transport modules or Subunits of such synchronous transport modules, so-called virtual Containers VC-N (in SDH) or Virtual Tributaries VT (SONET), packed and transmitted to the second network element NE2, where they unpacked and forwarded to the connected second router RTR2. Besides SDH and SONET systems are also transmission systems plesiochronous digital hierarchy (PDH) as synchronous digital Communications networks within the meaning of the invention.

A logical connection (often referred to as a virtual connection) created by two network elements periodically subunits synchronous replace transport modules and sub-units while in other intervening network elements of the communications network SDH are durchgescholtet without repackaging. Virtual connections be from a central network management system of the synchronous digital data transmission network SDH furnishings and a fixed transmission capacity, ie it is located permanent virtual connections.

A basic idea of ​​the invention is, in the Communications network to monitor the destination addresses of the transporting data packets provide, from the Traffic between the individual network elements of to determine the communications network and based on the Traffic an optimized configuration of logical connections to determine, with the network is updated. This is the power adapted the current volume of traffic and the Transmission capacity of the network are used to best. This Approach is particularly useful with IP data packets of Internet applications , but is also available for data packets, the other to Protocols are preferably constructed of OSI layer 3 as For example, the IPX protocol from the company. Novell Inc., applicable.

It is particularly advantageous, the monitoring of the destination addresses in at least a portion of the network elements of the synchronous digital make Nachrichtenübertragunsnetzes. These include the Network elements via means for monitoring the destination addresses, for example via an IP address monitor. Continue it is advantageous to determine the volume of traffic and the Determining an optimized configuration in a central Management system of the communications network make. The network elements notify the management system of the results Monitoring with the destination address, from which the management system, the can determine traffic. Via the interfaces (eg, a Q-interface), on the management system with the network elements is connected, then instructions are sent to the network elements, concerning logical connections, the switch from the network elements are. In this way the management system establishes the logical Compounds in accordance with the optimized configuration in the network.

It is advantageous periodically to determine an optimized configuration and the logical connections to update periodically. This may vary after application, for example, daily, hourly or even minute by minute done (pseudo online)

Figures 2a and 2b show three network elements CC1-CC3 of the synchronous digital communications network in one embodiment of the Invention, wherein the first and second and the second and third are physically interconnected network element, for example by Optical fibers (fibers) or coax cable. In the figure, however, not shown the physical connections. In the drawn Compounds which form are logical connections. The three Network elements are each connected via an interface to a central Management system TMN connected. From this they can instructions obtained which logical connections are to be connected internally. To the three network elements CC1-CC3 is a respective router RTR1-RTR3 connected, the access of an unrepresented local Data network to the transmission network forms. The router forwards Data packets from the local area network connected him respectively, the intended for an addressee in another local area network are at the its affiliated network element further, where the data packets in Subunits of synchronous transport modules packaged and a logical connections are transmitted to another network element.

According to the invention takes place in the sendenen network element before packing a data packet each to monitor the destination address instead. The Result of this monitoring is in the form of an announcement to the MTL central management system TMN forwarded. It can also Results of the monitoring of multiple data packets to be transmitted summarized and as a message MTL to the management system TMN sent.

In the configuration shown in Figure 2a exists between two adjacent network elements each have two logical connections while between the two remote network elements CC1 and CC3 no logical Connection. This configuration is suitable for high Data traffic between the adjacent network elements CC1 and CC2 and CC2 and CC3. Traffic between remote Network elements, ie, data packets that are sent from CC1 to CC3 should have unpacked in CC2, the LW Router RTR2 are fed, checked there and returned to CC2, from where it then can be transmitted to CC3.

In all three network elements monitoring the destination addresses will all by the relevant network element to transmit data packets instead. The Result of all monitors is the central management system TMN communicated as messages MTL. determines the management system TMN from these messages determines the current traffic and therefrom an optimized configuration, then with the logical Connections in the transmission network will be updated, by the management system to the network elements instructions ANW transmitted relating to the logical connections of each network element should switch.

If now increased traffic between the remote network elements CC1 and CC3 on with, the management system TMN that a optimized configuration, a logical connection between the Network elements CC1 and CC3 is necessary and sends it to the Network elements CC1-CC3 respectively an instruction ANW, the corresponding Connection to switch, ie one for the logical to be established Compound representative virtual container from the first network element CC1 in the second network element CC2 switch through the third CC3. The optimized configuration for data traffic between the remote Network elements CC1 and CC3 is shown in Figure 2b. By Optimization of data throughput for IP packets increases and the Lead times reduced by the communications network.

Of the IP routers would be of such an optimization of the Communications network is not possible, since this does not have knowledge of have the topology of the network. In contrast to newly established or no longer existing logical connections of the routers automatically detected and used or bypassed, for example by the so-called polling method. Therefore, Router that dynamically optimized by the inventive process by low detection times use transmission network for routing.

Be advantageous also proves that the at the entrances Transmission network standard router Major Schittstellen can be used, for example, E1, E3, E4, T1, T3, DS1, DS3, OC-n or STM-n interfaces. Also on the devices of Users are no modifications required.

It is expedient for the monitoring of the destination addresses in cross-connectors is perform, whose job it is, logical connections in a synchronous digital communication network to switch.

A development of the invention is not only the destination addresses the data packets to monitor, but also the return addresses. On this manner, for example by simple counting of the transmitted Data packets for each sender, charging for the transfer be realized by data packets.

According to another embodiment of the invention, after predetermined criteria preferably selected data packets, ie with a treated higher priority. Such criteria may include in particular its sender or destination addresses of IP packets. In this manner, selected users who pay a higher tariff for example, provided a safer and faster data connection available will.

Another development of the invention provides that in determining the optimized configuration also experiences over cyclically occurring Traffic situations are considered. Such experiences can eg also by statistical analysis over longer periods of time or the typical behavior of individual users can be obtained. Thus, for example be known from observations that two users always Sunday nights perform data synchronization with a high volume of traffic. The regularly required for this transaction transmission capacity is then automatically of the management system shortly before Start of data transmission in the form of a logical connection to made available and dismantled after completion of the transaction.