EP2130329A1

EP2130329A1 - Method for reconfiguring a communications network

Info

Publication number: EP2130329A1
Application number: EP08717849A
Authority: EP
Inventors: Martin Nathansen; Vivek Kulkarni; Elie Sfeir
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2007-03-30
Filing date: 2008-03-14
Publication date: 2009-12-09
Also published as: US8284658B2; US20100110884A1; DE102007015539A1; DE102007015539B4; CA2682425A1; CN101652963B; CN101652963A; WO2008119649A1

Abstract

The invention relates to a method for reconfiguring a packet-switched communications network with a first network using a first network protocol, and a second network using a second network protocol different from the first network protocol, in which the two networks are connected together using at least three redundant data links, only one of which is activated for exchanging useful data, wherein a master data link is initialized as activated and at least two slave data links are initialized as inactivated, characterized by the following steps: detection of a failure of the master data link or a failure of a slave data link by a master bridge of the second network connected to the master data link; generation of a first data packet by the master bridge and transmission of the first data packet to a slave bridge of the second network connected to a slave data link, wherein the slave bridge is selected by the master bridge according to a specifiable selection rule; the receiving and processing of the first data packet by the selected slave bridge, wherein the first data packet contains logical information by means of which the at least partial execution of the first network protocol is initiated on a port of the slave bridge connected to the slave data link, and activation of the slave data link by the first network protocol executed on a port of the slave bridge is also initiated.

Description

description

Method for reconfiguring a communication network

The invention is in the technical field of packet-switched communication networks and relates to a method for reconfiguring a communication network in which LANs using different network protocols are interconnected.

Packet-switched Local Area Networks (LANs) are used in both the industrial environment and the office environment, with very different requirements for the networks. In contrast to the office environment, LANs have to work reliably in everyday industrial environments under extreme conditions such as electromagnetic interference fields, high operating temperatures and mechanical stresses. Since the failure of a production plant and the associated downtimes are usually associated with high costs, it is added that in industrial applications, the requirements for reliability are higher than in office environment.

For industrial LANs, for this reason, robust components are used which enable fast redundancy mechanisms in order to keep costs as low as possible in the event of a fault. In addition, a ring topology is usually chosen for the network, as it enables a fast reconfiguration time of less than 500 ms in the event of a data link or bridge failure. Network protocols typically use Ethernet standard based or proprietary network protocols for industrial LANs.

In contrast, LANs in the office environment are usually constructed in a star or mesh topology and as a network protocol these days typically use RSTP (Rapid Spanning Tree Protocol) in accordance with IEEE standard 802. Iw. In practical applications, ring-shaped industrial LANs are connected to one another via meshed Office LANs via data links. In order to increase the resilience of such connected networks, it is known to set up two redundant data links between the two networks, of which only a first redundant data link is activated for data exchange between the two networks, while the second redundant data link is blocked and as a backup - Data link is activated only in case of failure instead of the activated first data link. The disadvantage here is the fact that the switching process for activating the blocked second data link takes comparatively much time and takes about 30 seconds when using the standardized routines of RSTP in the office LAN.

For this reason, it would be desirable to have a method for reconfiguring a communication network connecting two LANs, which allows faster reconfiguration in the event of failure of a data link connecting the two LANs, as compared to the conventional methods.

This object is achieved erfmdungsgemaß by a method for reconfiguring a packet-switched communication network with the features of claim 1. Advantageous embodiments of the invention are indicated by the features of the subclaims.

To solve the problem erfmdungsgemaß a method for reconfiguring a packet-switched communication network is shown, which comprises a (geswitchtes by bridges) first network and a (geswitchtes by bridges) second network, which are connected to each other via at least three redundant data links, respectively only one is activated for the user data exchange. Here and below are referred to as "redundant data links" only connecting the two networks of the communication network data links. The network nodes of the communications network are referred to herein as "bridges." Nevertheless, it can be in the Acts of the invention also switch (switches = multiport bridges) or other suitable for switching network nodes act.

The at least three redundant data links are a master data link which can be presettable activated or activated and used for the user data exchange and at least two presettable inactivatable or inactivated slave data links which can be used for the user data exchange in the event of failure of the master data link ,

The redundant data links each connect a bridge of the first network and a bridge of the second network data-technically together. Each bridge of the second network can in each case be connected to a separate bridge of the first network. Likewise, it is possible for multiple bridges of the second network to be connected to different ports of a same bridge of the first network.

The bridge of the second network connected to the master data link is referred to here and below as the master bridge. The respective bridges of the second network connected to a slave data link are referred to here and below as slave bridges. Master and slave bridges of the second network may each be assigned individual path costs, with the master bridge being assigned the lowest path cost of all bridges connected to a redundant data link of the second network. The path costs assigned to the master and slave bridges of the second network can be stored in the master bridge in a corresponding data storage device. The path costs allocated to the master and slave bridges of the second network can in particular be transmitted by means of signals from the slave bridges to the master bridge, in particular based on the second network protocol.

The first network of the communication network can msbeson- be installed as office LAN in a office environment. For the first network, a first network protocol has been set up for data exchange. The first network protocol used in the first network is preferably RSTP according to IEEE standard 802. Iw, which forms a logical topology in the form of a spanning tree on the physical topology of the first network. The first network preferably has a meshed or star-shaped physical topology.

The second network of the communication network can be installed, in particular, as an industrial LAN in an industrial environment and uses a second network protocol based in particular on the Ethernet standard for data exchange, which can be a standard or proprietary network protocol. The network protocol of the second

Network is different from the first network protocol, especially RSTP. The second network preferably has an annular topology.

The inventive method for reconfiguring the communication network comprises the following steps:

Detecting a failure of the (default) activated master data link by the master bridge of the second network connected to the master data link. The failure of the master data link can be detected, for example, by a lack of reception of a signal transmitted by the bridge of the first network connected to the master data link by the master bridge ("loss-of-signal"). The master bridge is provided for this purpose with a device for detecting a signal failure (hardware detector) of the data link. In this way, in particular a so-called hardware alarm of the master bridge can be triggered.

After detecting the failure of the master data link by the

Master bridge: Generation of a first data packet (N1) by the master bridge and transmission of the first data packet (N1) to a slave bridge of the slave bridge connected to a slave data link second network. The master bridge selects the slave bridge of the second network for transmission of the first data packet in accordance with a preselected selection rule. Advantageously, the first data packet (N1) is transmitted from the master bridge of the second network to the slave bridge of the second network by means of the second network protocol.

After transmission of the first data packet by the master bridge: receiving and processing of the first data packet by the slave bridge, wherein the first data packet contains logical information by which the at least partial execution of the first network protocol, in particular RSTP, on one with the slave Data link connected port of the slave bridge is triggered.

After activating the first network protocol for the slave link port connected to the slave link: Activation of the slave link by the first network protocol executed on the port of the slave link. Activation of the slave data link is preferably carried out by exporting a handshake mechanism defined in RSTP between the RSTP port of the slave bridge of the second network connected to the inactivated slave data link and a bridge of the first link connected to the inactivated slave data link network. Activation of the inactivated slave data link takes place here by means of routines standardized in RSTP.

By erfmdungsgemaße method, a rapid reconfiguration of the logical topology in case of failure of the two LANs connecting data links (master Datenlmk) can be achieved in an advantageous manner.

In the event of a failure of a slave data link activated after failure of the master data link, the method according to the invention advantageously comprises the further steps:

Detecting the failure of the activated slave data link by a slave bridge of the second network connected to the slave data link. The failure of the activated slave data link can, for example, based on a lack of receiving a signal sent from the connected to the slave data link bridge of the first network signal through the

Slave bridge of the second network can be detected. The slave bridge is equipped for this purpose with a device for detecting a missing signal reception (hardware detector). As a result, in particular, a hardware alarm of the slave bridge can be triggered.

After detecting the failure of the slave data link by the slave bridge: Generation of a second data packet (N2) by the slave bridge and transfer of the second data packet (N2) to the master bridge. Advantageously, a transmission of the second data packet from the slave bridge of the second network to the master bridge of the second network takes place by means of the second network protocol.

After transmission of the second data packet by the slave bridge: receiving and processing of the second data packet (N2) by the master bridge, wherein the second data packet contains logical information by which the master bridge is informed about the failure of the slave data link.

After detecting the failure of the slave data link through the master bridge, the following steps are preferably performed:

Re-generating a first data packet (Nl) by the master bridge and transmitting the first data packet (Nl) to a slave bridge of the second network connected to a slave data link (not failed). In this case, the master bridge selects the slave bridge of the second network for transmission of the first data packet in accordance with the preselectable selection rule. Advantageously, the first data packet (N1) is transferred from the master bridge of the second network to the slave bridge of the second network by means of the second network protocol. factory transfer.

Receiving and processing of the first data packet by the selected slave bridge, wherein the first data packet contains logical information by which the at least partially execution of the first network protocol, in particular RSTP, is triggered on a connected to the slave data link port of the slave bridge.

After activating the first network protocol on the slave link port of the slave bridge: Activation of the slave data link by the first network protocol executed on the port of the slave bridge. The slave data link is preferably activated by executing a handshake mechanism defined in RSTP between the RSTP port of the slave bridge of the second network connected to the inactivated slave data link and a bridge of the first link connected to the inactivated slave data link network. Activation of the inactivated slave data link takes place here by means of routines standardized in RSTP.

The method for activating a further inactivated slave data link in the event of failure of a slave data link activated after failure of the master data link can be repeated for all slave data links of the communication network.

By means of the above method, rapid reconfiguration of the logical topology in the event of a failure of a data link (slave data link) connecting the two LANs can advantageously be achieved.

In a particularly advantageous manner, a selection of the slave bridges for activating the slave data links connected to the slave bridges is carried out according to the slave bridges in each case allocated path costs. For this purpose, the master bridge and the slave bridge of the second network are path costs, in particular RSTP path costs, for example by the Assigned to network protocol. Particularly advantageous are the master bridge here assigned the lowest path costs.

After failure of the master data link, the master bridge for activating a slave data link advantageously selects those slave bridges which are assigned the subsequent path costs with respect to the master bridge. In the event of failure of an activated slave data link, the master bridge advantageously selects that slave bridge which has the post-medium path costs with respect to the slave bridge of the failed slave data link. In this way, it can be ensured that the data connection between the two networks always has the lowest possible path costs.

In a further advantageous embodiment of the method according to the invention, this comprises the following further steps:

Capture the recovery of the failed master data link by the master bridge of the second network. Detection occurs, for example, by reinstating receiving signals, such as RSTP congestion frames, through the master bridge of the second network.

After detecting the recovery of the master data link by the master bridge: Generation of a third data packet (N3) by the master bridge and transfer of the third data packet to the slave bridge of the activated slave data link. Advantageously, the third data packet is transmitted to all slave bridges. This informs the slave bridges of the activated and deactivated slave data links about the restoration of the master data link.

After transmission of the third data packet: receiving and processing of the third data packet by the slave bridge (s), wherein the third data packet contains logical information, by which termination of the execution of the first network protocol, in particular RSTP, on the slave bridge or a termination of the transmission of RSTP configuration frame by the slave bridge is effected.

Then: Activation of the master data link and deactivation of the activated slave data link.

As a result, a rapid reconfiguration of the logical topology when restoring the master data link can be achieved in an advantageous manner.

In an advantageous embodiment of the method according to the invention, the following steps are performed to activate the restored master data link and to deactivate the second slave data link after detecting the restoration of the master data link by the master bridge:

At least partial execution of the first network protocol, in particular RSTP, on a connected to the master data link port of the master bridge.

The master data link is preferably activated by exporting a handshake mechanism implemented in RSTP between the bridges of the first and second network which are directly connected to the master data link. In addition, forwarding of an RSTP congestion frame generated during the handshake mechanism for activating the master data link by the master bridge to the bridge of the first network connected to the activated slave data link, thereby inactivating the activated slave data link.

Completion of the execution of the first network protocol, in particular RSTP, on the master bridge port connected to the master data link.

This can advantageously a particularly rapid reconfiguration of the logical topology in recovery of the master data links, in particular using routines implemented in RSTP.

The invention further extends to a search as described above schπebenes packet-switched communications network with egg ^¬ nem a first network protocol onset first network and a different from the first network protocol second network protocol onset of the second network, in which the two networks interconnected by at least three redundant data links are, of which only one is activated for user data exchange, wherein a master data link is activated by default and at least two slave data links are disabled by default. In the Kom ^¬ munikationsnetzwerk are the bridges, in particular associated with a slave data link bridges, each turned so directed ^¬ that a process as described above is ausfuhrbar.

Furthermore, the invention extends to a master bridge of a packet-switched communication network as described above. In addition, the OF INVENTION ^¬ extension extends to a slave bridge a pa ^¬ ketvermittelten communication network as described above.

The invention will now be explained with reference to an exemplary embodiment na ^¬ ago, reference being made to the attached drawings. Show it:

Fig. 1A-1D are schematic representations to illustrate an exemplary embodiment of the erfmdungsgemaßen

Method for reconfiguring a Kommunikati ^¬ onsnetzwerks.

In Figs. 1A-1D schematically a Ausfuhrungs- example of the inventive communication network is open ^¬ shows. The designated as a whole by reference numeral 1 comprises a communi ^¬ nikationsnetzwerk installed in a Buroumgebung, maschenformiges, office, switched by bridges LAN 2 and an industrial-environment-installed annular bridge-switched industrial LAN 3.

The physical topology of the office LAN 2 includes four bridges 4-7 which are meshed with each other in a meshed fashion via respective point-to-point links (data links). In the figures, the data links are shown by solid lines and not otherwise denoted.

In the office LAN 2, the IEEE standard 802. Iw standardized network protocol RSTP is executed. By means of the network protocol RSTP used in the office LAN 2, a logical topology in the form of a spanning tree is formed on the physical topology of the office LAN 2 given by the bridges and data links, which is used exclusively for the exchange of user data packets. In the figures, the spanning tree is not nearer marked.

The RSTP network protocol assigns unique identifiers (IDs) and path costs to all RSTP bridges and RSTP ports on the office LAN 2. In RSTP, the bridges automatically cover the logical topology of the network by means of the data packets (data frames) passing through them, using the layer addresses of the network (MAC addresses, MAC = Medium Access Control) of the bridges.

In RSTP, the ports of the bridges can assume different states, in particular a state "Blockmg", in which only configuration frames, so-called BPDUs (BPDU = Bridge Protocol Data Umt), are accepted by the bridges, a state "Listenmg", during the the active logical topology is formed in the form of a spanning tree, a state "learning", during which a Bridgmg table is compiled from the read MAC addresses, a state "Forwarding", in which the ports forward useful data, and a Disabled state in which ports receive or forward neither payload nor BPDUs. With the help of the information contained in the BPDUs, the bridges can change the state of their Change ports.

Each configuration frame (BPDU) contains a series of fields, such as a flag field for indicating or confirming a topology change, a rootbuck ID field for identifying the rootbruck indicating priority and ID, a path cost field for specifying the path cost of the root bridge sending the BPDU , a message age field (MessAge) for specifying the period since the BPDU was sent, a MaxAge field for specifying a time after which the message is to be deleted, a Hello time field for specifying the period between regular configuration messages (Hello signals) the root bridge, and a forward delay field that indicates the wait time after a topology change.

To form a loop-free logical topology, RSTP uses four criteria to determine the highest priorities of the bridges or their ports. These are: the smallest Rootbrucken-ID, the lowest path cost to the Rootbrucke, the smallest Sendebrucken-ID and the smallest Port-ID.

In order to determine a root bridge, in RSTP all ports of the bridges after initialization (for example, after a restart of the network) first in the state "Blockmg", each bridge assumes that it is itself a root bridge and a corresponding BPDU with their own Send ID as Rootbruck ID to the other bridges. Then the bridge with the lowest Rootbrucken-ID is used as rootbruck. If the rootbruck ID is identical, the lowest MAC address is used as a supplementary criterion.

From the selected root bridge, all network paths of the spanning tree are then determined, via which a data exchange between the bridges in the communication network is to take place. For this purpose, the root bridge first sends BPDUs to the other bridges. Each bridge then determines as root Port a port that has the lowest path cost to Rootbrucke. In the case of equal path costs, the port ID is used as a supplementary criterion. Subsequently, designate ports are determined based on the path cost and the designated bridges of the spanning tree are determined.

In RSTP, the root bridge tells all bridges in the spanning tree at regular intervals via a corresponding BPDU (hello signal) that it is still there. If such a hello signal fails, for example because of the failure of a link or the root bridge itself, a reconfiguration of the communication network is required to determine a new spanning tree. Since at this time only BPDUs, i. H. Data packets are transmitted to determine a new spanning tree, the communication network for this period for a user data exchange is not usable.

RSTP also identifies alternative ports that block BPDUs from other bridges and provide an alternative route to the root bridge if the root port goes down.

Furthermore, a proposal / agreement handshake mechanism between directly connected bridges is implemented in RSTP. By means of the Proposal / Agreement handshake mechanism, RSTP bridges automatically send BPDUs to the neighboring bridges at predeterminable intervals. RSTP specifies that a bridge loses its link to a neighboring bridge if it can not receive BPDUs within a predefined time period. In this way, a failure of a link can be detected quickly.

The topology of the industry LAN 3 includes six bridges 8-13 which are annularly connected to each other via respective point-to-point data links. In the figures, the data links between the bridges are shown by a solid line and not otherwise denoted.

In the industrial LAN 3, an Ethernet standard is used. implementing proprietary network protocol, which is different from the network protocol RSTP of the office LAN 2. Therefore, in contrast to the RSTP bridges of the office LAN 2, the bridges 8-13 are referred to here and below as "propable bridges" of the industrial LAN 3.

The office LAN 2 and the industrial LAN 3 are connected to each other via three redundant data links 14-16 in terms of data technology. These are a default activated for the user data exchange Master Datenlmk 14 and two for the user data exchange preset inactivated slave data links 15, 16.

FIG. 1A shows an initial situation for carrying out the method according to the invention, in which the master data log 14 is activated and the two slave data links 15, 16 are inactivated. In FIG. 1A, the activated master data log 14 is therefore represented by a solid line, while the two inactivated slave data links 15, 16 are shown by broken lines. The two slave data links 15, 16 serve as activatable redundant connections (back-up Datenlmks) between the two networks 2, 3rd

The master data link 14 is connected to an RSTP port of the RSTP bridge 6 of the office LAN 2 and a proprietary port of the proprietary bridge 8 ("master bridge") of the industrial LAN 3 which uses the proprietary network protocol. Em first slave data link 15 is connected to an RSTP-executing RSTP port of the RSTP bridge 7 of the office LAN 2 and a proprietary port of the proprietary bridge 9 of the industrial LAN 3. The second slave data link 16 is connected to an RSTP port of the RSTP bridge 5 of the office LAN 2 and to a proprietary port of the proprietary bridge 13 of the industrial LAN 3. In this respect, each data link between the two networks 2, 3 connects a bridge of one network to a separate bridge of the other network. Both ports connected to the master data interface 14 are activated, in particular the RSTP port of the RSTP bridge 6 of the office LAN 2 being in its "forwardmg" state. In order to block the first slave data link 15, the RSTP port of the RSTP bridge 7 of the office LAN 2 connected to the first slave data link 15 is set in its "Blockmg" state. In order to block the second slave data link 16, the RSTP port of the RSTP bridge 5 of the office LAN 2 connected to the second slave data link 16 is set to its "Blockmg" state.

In the communication network 1 shown in the figures, the RSTP bridges of the office LAN 2 and the bridges 8, 9, 13 of the industrial LAN 3 directly connected to the office LAN 2 via the data links 14-16 are RSTP path costs assigned. In the master bridge 8 of the industrial LAN 3 connected to the master data link 14, the path costs of all bridges of the industrial LAN 3 directly connected to the office LAN 2 are stored in a data storage device. Alternatively, the path costs of the slave bridges of the industrial LAN 3 directly connected to the office LAN 2 can be sent to the master bridge 8 via messages (data packets) generated by the slave bridges, in particular based on the proprietary network protocol of the industrial LAN 3 become.

FIG. 1B shows a situation in which, starting from the situation illustrated in FIG. 1A, with activated master data memory 14, this has fallen out for the payload data transmission. In Fig. IB, the failed master data file 14 is shown by a broken line. The failure of the activated master data link 14 is detected by the two bridges connected by the master data link 14 by a missing signal reception ("loss of signal") by a corresponding device for detecting a missing signal reception (hardware detector). In the master bridge 8 of the industrial LAN 3, this triggers a hardware alarm, as a result of which a first data packet N 1 from the master station Bridge 8 is generated.

Then, the master bridge 8 among the two slave bridges 9, 13 selects those to which the smaller RSTP path costs are assigned. In the exemplary embodiment of FIG. 1B, this is the slave bridge 9 of the first slave data link 15.

Subsequently, using the proprietary network protocol of the industrial LAN, the master bridge 8 sends the first data packet N1 via the corresponding data link of the ring-shaped industrial LAN 3 to the slave bridge 9 connected to the first slave data link 15. The first data packet N1 contains logical information by which the slave bridge 9 is informed that the master link 14 for the user data exchange has failed. For this purpose, in the first data packet N1, for example, a flag "Fallen-Master-Datenlmk" is set.

By receiving and processing the first data packet Nl by the slave bridge 9, a partial or complete execution of the network protocol RSTP according to IEEE standard 802. Iw is triggered on that port of the slave bridge 9, which is connected to the first slave Datenlmk 15 , As a result, the slave bridge 9 of the Industπe LAN 3 appears opposite the office LAN 2 as an RSTP bridge.

The slave bridge 9 of the industrial LAN 3 is in this case a highest bridge ID, ie the lowest priority assigned to all RSTP bridges of the office LAN 2, whereby it can be ensured that the slave bridge 9 is in formation a spanning tree of the office LAN 2 is not undesirably chosen as the new root bridge.

Subsequently, the slave bridge 9 of the industrial LAN 3, which is now provided with an RSTP port, generates a first RSTP signal.

Conflagration frame (RSTP-BPDUl) and sends the first RSTP congestion frame through its RSTP port via the first slave data link 15 to the first slave data link. bound RSTP bridge 7 of the office LAN 2. The RSTP configuration frame RSTP-BPDUl is a suggestion message (pro posal) for activating the link to the first slave data link 15 (blocked) within the framework of the handshake mechanism implemented in RSTP ) RSTP ports of the RSTP bridge 7 of the office LAN 2.

Upon receiving and processing the first RSTP congestion frame through the RSTP bridge 7 of the office LAN 2, the RSTP bridge 7 generates a second RSTP congestion frame

(RSTP-BPDU2) and sends the second RSTP-Conflgurationsrahmen to the slave bridge 9 of the Industπe-LAN 3. The second RSTP-Schwiergurationsrahmen is another suggestion message (Proposal).

Upon receipt and processing of the second RSTP configuration frame by the slave bridge 9, it generates a third RSTP Conflicting Frame (RSTP-BPDU3) and sends the third RSTP Confluration Frame to the RSTP Bridge 7 of the Industrial LAN 3. The third one RSTP Conflict Framework is an agreement (Agreement). Upon receipt of the acknowledgment message, the RSTP port of the RSTP bridge 7 of the first slave data link 15 is set in its "Forwardmg" state, which places the blocked first slave data link 15 in its active state, which exchanges useful data between the two both networks. This is illustrated in FIG. 1B by a solid line for the first slave data link 15. The handshake mechanism for activating the blocked RSTP port connected to the first slave data link 15 corresponds to the routines standardized according to IEEE standard 802. Iw.

FIG. 1C shows a further situation in which the first slave data link 15 activated for user data transmission has failed. The failure of the first slave data link 15 is detected by the slave bridge 9 connected to the first slave data link 15, for example by a hardware detector detecting the lack of reception of configuration BPDUs, which can be transmitted from the bridge 7 of the office LAN 2, can capture. In the slave bridge 9 of the industrial LAN 3, this triggers a hardware alarm, as a result of which a second data packet N2 is generated by the slave bridge 9.

Subsequently, using the proprietary network protocol of the industrial LAN 3, the slave bridge 9 sends the second data packet N2 via the corresponding data link of the ring-shaped industrial LAN 3 to the master bridge 8 connected to the master data link 14. The second data packet N2 contains logical information by which the master bridge 8 is informed that the first slave data link 15 has failed for the user data exchange. For this purpose, for example, a flag "Fold-out slave data link" is set in the second data packet N2.

In the master bridge 8 of the industrial LAN 3, the detection of the failure of the first slave data link 15 by means of the second data packet triggers a hardware alarm, as a result of which a first data packet N 1 is again generated by the master bridge 8 ,

Then, the master bridge 8 selects the next slave bridge 13 for transmission of the generated first data packet Nl. The master bridge 8 selects such a slave bridge, which are assigned the next lowest RSTP path costs with respect to the slave bridge 9 connected to the failed first slave data link 15, in this case the slave bridge 13.

Subsequently, using the proprietary network protocol of the industrial LAN, the master bridge 8 sends the first data packet N1 via the corresponding data link of the ring-shaped industrial LAN 3 to the slave bridge 13 connected to the second slave data link 16. The first data packet N1 ent - Holds logical information by which the slave bridge 13 is informed that the master data link 14 has failed for the user data exchange. For this purpose, in the first data packet N1, for example, a flag "Failed" Master data link ".

By receiving and processing of the first data packet Nl by the slave bridge 13 of the second slave data link 16, a partial or complete execution of the network protocol RSTP according to IEEE standard 802. Iw is triggered on that port of the slave bridge 13, with the second Slave data link 16 is connected. As a result, the slave bridge 13 of the industrial LAN 3 appears opposite the office LAN 2 as an RSTP bridge.

Then it will generate the now RSTP port

Slave bridge 13 of the industrial LAN 3 a first RSTP

Conflagration frame (RSTP-BPDUl) and sends the first RSTP configuration frame through its RSTP port via the second slave data link 16 to the RSTP bridge 5 of the office LAN 2 connected to the second slave data link. The RSTP configuration frame As part of the handshake mechanism implemented in RSTP, RSTP-BPDU1 is a proposal message (pro posal) for activating the (blocked) RSTP port of bridge 5 of the office LAN 2 connected to the second slave data link 16.

Upon receiving and processing the first RSTP congestion frame through the RSTP bridge 5 of the office LAN 2, the RSTP bridge 5 generates a second RSTP congestion frame (RSTP-BPDU2) and sends the second RSTP congestion frame to the slave bridge 13 of the Industrial LAN 3. The second RSTP Conflicting Frame is another Proposal Message (Proposal).

Upon receipt and processing of the second RSTP configuration frame by the slave bridge 13, it generates a third RSTP Conflict Frame (RSTP-BPDU3) and sends the third RSTP Confluration Frame to the bridge 5 of the Industrial LAN 3. The third RSTP Conflict frame is an understanding message (Agreement). Upon receipt of the acknowledge message, the RSTP port of bridge 5 of the second Slave data links 16 in its "Forwardmg" state, whereby the blocked second slave data link 16 is set to its active state, in which a user data exchange between the two networks is enabled. This is shown in Fig. IC by a solid line for the second

Slave data link 16 illustrated. The handshake mechanism for activating the blocked RSTP port connected to the second slave data link 16 corresponds to the routines standardized according to IEEE standard 802. Iw.

In Fig. ID, another situation is shown in which the master Datenlmk 14 is restored after its failure. The master bridge 8 of the industrial LAN 3, which is connected to the master data link 14, recognizes via incoming signals which are connected to the master data link 14

Bridge 6 of the office LAN 2, the recovered Master Datenlmk 14. The detection of the signals is carried out by the hardware detector, which has also detected the absence of signals. This tπggert the generation of a third data packet N3 by the master bridge. 8

The third data packet N3 is then sent by means of the proprietary network protocol of the Industπe LAN 3 via the corresponding data links of the Industπe LAN 3 to the slave bridges 9, 13. The third data packet N3 informs the slave bridges 9, 13 that the master data memory 14 has been restored. For this purpose, in the third data packet N3, for example, a flag "failed master data file" has been deleted.

By the reception and the processing of the third data packet N3 by the slave bridges 9, 13, a termination of the execution of the network protocol RSTP for the respective port of the slave bridges connected to the slave data link is triggered in each case. The connected to the slave data links ports of the slave bridges 9, 13 are thus each changed from an RSTP port back to one of the proprietary network protocol of the Industπe LAN 3 controlled port. The SIa- ve-bridges 9, 13 no longer appear to the office LAN 2 as RSTP bridges.

The detection of the restored master data link 14 by the master bridge 8 further tπgggert the partial or complete execution of the network protocol RSTP according to IEEE standard 802. Iw (only) on that port of the master bridge 8, with the blocked master Datenlmk 14 is connected. As a result, the master bridge 8 appears opposite the office LAN 2 as RSTP bridge.

The generated now with an RSTP port

Master bridge 8 of the industrial LAN 3 a first RSTP

Conflagration Frame (RSTP-BPDUl) and sends the first RSTP configuration frame through its RSTP port connected to the master data link 14 to the RSTP bridge 6 of the office LAN 2 connected to the master data link 14. This is shown in Fig. ID illustrated by an arrow. The configuration frame RSTP-BPDU1 is a proposal (proposal) within the framework of the handshake mechanism implemented in RSTP.

Upon receiving and processing the first RSTP congestion frame through the RSTP bridge 6 of the office LAN 2, the RSTP bridge 6 generates a second RSTP congestion frame (RSTP-BPDU2) and sends the second RSTP congestion frame to the master bridge 8. This is also illustrated by an arrow in Fig. ID. The second RSTP Conflicting Framework is a proposal to activate the blocked RSTP port of the Office LAN 2 bridge 6 connected to the Master Data Link 14.

Upon receipt and processing of the second RSTP configuration frame, master bridge 8 of industry LAN 3 generates a third RSTP congestion frame (RSTP-BPDU3) and transmits the third RSTP congestion frame through its RSTP frame connected to master data library 14. Port to the RSTP bridge 6 of the office LAN 2 connected to the master data interface 14. This is illustrated by an arrow in FIG. The third RSTP configuration frame is an agreement to activate the blocked RSTP port of the bridge 6 of the office LAN 2 connected to the master data link 14.

The blocked RSTP port of the RSTP bridge 6 of the office LAN 2 connected to the master data link 14 is then set to its "forwarding" state. As a result, the blocked master data link 14 is set to its active state, so that a user data exchange between the two

Networks 2, 3 on the master data link 14 is enabled.

The above-mentioned handshake mechanism for activating the blocked RSTP port of the RSTP bridge 6 of the office LAN 2 connected to the master data link 14 is performed by routines standardized in the IEEE 802. Iw standard.

Furthermore, the second RSTP configuration frame (RSTP-BPDU2) received from master bridge 8 of industrial LAN 3 is forwarded unchanged to slave bridge 13 connected to second slave data link 16. Forwarding takes place here by the proprietary network protocol of the industrial LAN 3. After receiving, the slave bridge 13 connected to the second slave data link 16 forwards the second RSTP configuration frame (RSTP-BPDU2) unchanged to the second slave data link 16 connected RSTP bridge 5 of the office LAN 2 on. Thereupon, the RSTP port in the "Forwarding" state of the RSTP bridge 5 of the office LAN 2 connected to the second slave data link 16 is set to its "blocking" state, so that the second slave data link 16 is deactivated.

Subsequently, after activation of the master data link 14 and after forwarding of the second RSTP configuration frame (RSTP-BPDU2) by the master bridge 8 of the industrial LAN 3, a termination of the execution of the network protocol RSTP for the master data link 14 Connected port of the master bridge 8 triggered. The one with the master data link 14 Connected port of the master bridge 8 is thus changed from an RSTP port back to one of the proprietary network protocol of the Industπe LAN 3 controlled port. The master bridge 8 then appears to the office LAN 2 no more than an RSTP bridge.

By means of the method according to the invention, a reconfiguration of a multi-redundant data connection of two networks using different network protocols can be achieved in a simple manner. In particular, an RSTP

Network are connected to another network in ring topology multi-redundant, with the Rekonflgurations- times for reconfiguring a data link connecting the two networks are very short. A restriction to a single redundant backup data is not necessary. In this way, a data connection between the two networks can be maintained even in the event of multiple failures of data links connecting the two networks. The complexity for configuring such a communication network is low.

Claims

claims

A method of reconfiguring a packet-switched communication network (1) having a first network (2) employing a first network protocol and a second network (3) employing a second network protocol different from the first network protocol, in which the two networks are characterized by at least three redundant ones Data links (14, 15, 16) are interconnected, of which only one is activated for user data exchange, wherein a master data link (14) is activated by default and at least two slave data links (15, 16) are disabled by default, characterized by the following steps:

Detecting a failure of the master data link (14) or a failure of an activated slave data link (15, 16) by a master bridge (8) of the second network (3) connected to the master data link (14); Generating a first data packet (Nl) by the master bridge (8) and transmitting the first data packet (Nl) to a slave bridge connected to a slave data link slave bridge of the second network, the slave bridge according to a predetermined selection rule from the master Bridge is chosen;

Receiving and processing of the first data packet (Nl) by the selected slave bridge, wherein the first data packet contains logical information, by which the at least partially execution of the first network protocol on a connected to the slave data link port of the slave bridge and an activation of the Slave data links are triggered by the executed on the port of the slave bridge first network protocol.

2. The method of claim 1, wherein the first data packet (Nl) is transmitted by means of the second network protocol from the master bridge (8) of the second network (3) to a slave bridge of the second network.

3. The method according to any one of claims 1 to 2, wherein detecting the failure of the master data link (14) by the master bridge (8) connected to the master data link due to a signal no longer received by the master bridge (8) from that associated with the master data link (14) Bridge (6) of the first network (2) takes place.

4. The method according to any one of claims 1 to 3, characterized by the steps:

Detecting a failure of an activated slave data link by a slave bridge of the second network connected to the slave data link;

Generating a second data packet (N2) by the slave bridge and transmitting the second data packet (N2) to the master bridge; - Receiving and processing of the second data packet (N2) by the master bridge, wherein the second data packet contains logical information by which the master bridge is informed about the failure of the activated slave Datenlmks (15).

5. The method of claim 4, wherein the second data packet (N2) is transmitted by the second network protocol from the slave bridge of the second network to the master bridge of the second network.

6. The method according to any one of claims 1 to 5, wherein the selected from the master bridge (8) slave bridge for transmitting the first data packet (Nl) according to the slave bridges each assigned path costs is selected.

7. The method of claim 6, wherein selected from the master bridge (8) in case of failure of the master data link (14) for activating a slave Datenlmks slave bridges with the lowest path costs.

8. The method according to any one of claims 1 to 7, wherein the first network protocol RSTP according to IEEE standard 802. Iw.

The method of claim 8, wherein the activation of a slave data link is performed by exporting a handshake mechanism implemented in RSTP between the bridges directly connected to the slave data link.

10. The method according to any one of claims 1 to 9, characterized by the following steps:

Detecting the recovery of the failed master data link (14) by the master bridge (8); Generating a third data packet (N3) by the master bridge (8) and transmitting the third data packet (N3) at least to the slave bridge connected to an activated slave data link; Receiving and processing of the third data packet (N3) by the slave bridge (13), wherein the third data packet contains logical information, by which an at least partial termination of execution of the first network protocol, in particular RSTP, on the slave bridge or termination of the Sending of RSTP configuration frame caused by the slave bridge, activation of the master data link (14), inactivation of the activated slave data link.

11. The method according to claim 10, wherein the third data packet (N3) by means of the second network protocol of the

Master bridge of the second network to a slave bridge (8) of the second network (3) is transmitted.

12. The method according to any one of claims 10 to 11, wherein the third data packet (N3) to all in each case with a

Slave Datenlmk connected slave bridges is transmitted.

13. The method according to any one of claims 10 to 12, wherein after detecting the restoration of the master data link (16) an at least partially execution of the first network protocol, in particular RSTP, on a connected to the master data link (14) port of the master Bridge (8) takes place.

14. The method of claim 13, wherein activating the master data link (14) by exporting an implemented in RSTP handshake mechanism between the directly to the master data link (14) directly connected bridges (6, 8).

15. The method according to claim 14, wherein for inactivating the slave data link (16), forwarding of a conflict frame generated during the handshake mechanism by the master bridge (8) to the slave data link (16 ) connected bridge (5) of the first network (2) takes place.

16. Method according to one of claims 13 to 15, in which after activation of the master data link (14) a termination of the execution of the first network protocol, in particular RSTP, on the port of the master computer connected to the master data link (14) Bridge (8) takes place.

17. A packet-switched communication network (1), comprising a first network (2) employing a first network protocol and a second network (3) employing a second network protocol different from the first network protocol, in which the two networks are interconnected by at least three redundant data links are each of which only one is activated for user data exchange, wherein a master data link (14) is activated by default and at least two slave data links (15, 16) are disabled in default, in which the bridges of each emgeπch- tet are, a method according to one of claims 1 to 16 can be executed.

18. master bridge of a packet-switched communication network according to claim 17.

19. slave bridge of a packet-switched communication network according to claim 17.