Method for assigning an IP-address to a device

p0001The invention relates to a method for assigning an IP address to a device, and a digital storage medium, a switch and a connectable to the switch device.

p0002assigning an Internet Protocol (IP) address to a device by means of DHCP (Dynamic Host Configuration Protocol) is known from the prior art. DHCP is commonly used in Local Area Network (LAN) environments used to assign IP addresses from a central address server.

p0003The choice of the device anforderndem assigned IP address meets the DHCP server to hand the local settings (Static or dynamic allocation) and the options provided in the DHCP request. Using DHCP Options (see. Website http://www.iana.org/assignments/bootp-dhcp-parameters) "# 12 hostname option", "# 43 Vendor Specific Option", "# 61 Client Identifier" "# 82 Relay Agent information", "# 128-254 private Use" or a newly defined further option, the DHCP server can be clearly assigned to a client, the stored IP address with him.

p0004must be LAN-wide unique in all variants in order to allow for this unique assignment of the selected identifier (ID).

p0005This identifier must be permanently saved in the client to obtain a reproducible result of the address resolution. As identifier for a client or a port of a client, for example, a UUID (Universal Unique Identifier) ​​or a DNS (Domain Name Service) name be used. In the DHCP server has multiple identifiers (alias) can be stored for an IP address.

p0006By "# 82 Relay Agent Information" of the DHCP, the IP address requesting terminal by the port of the switching node ( "switch") to which it is attached, must be precisely identified. The Option 82 is similar to an identification by Media Access Control (MAC) address. It has the advantage that the identification at the level 3 of the Open System Interconnection (OSI) -Schichtenmodells occurs and thus supported by the IP protocol (see. For this purpose<nplcit id="ncit0001" npl-type="s"><text>IEE 48. Class of 2003 No. 11, p. 32 to 34, "Network Management for Ethernet, step in the right direction," Frank Seufert</text></nplcit>).

p0007The allocation of IP addresses using DHCP and "# 82 Relay Agent Information" is also well known from the U.S. Patent Applications <patcit id="pcit0001" dnum="US20040010653A"><text>US-A-20040010653</text></patcit> and <patcit id="pcit0002" dnum="US20030101243A"><text>US-A-20030101243</text></patcit>,

p0008A disadvantage of the allocation of IP addresses using DHCP and Option 82 is that the switches are heavily burdened by the elaborate filtering of DHCP requests. A switch has means of such a filter to identify all DHCP request, and they refer to the data stream in order to enter or to see additional information that an entry already exists .. Then, the DHCP request is re-inserted into the data stream. This is particularly disadvantageous that efficient switching mechanisms such as cut-through will be made impossible.

p0009<patcit id="pcit0003" dnum="EP1081921B1"><text>EP 081 921 B1 1</text></patcit> discloses a method for assigning addresses in communication networks, in particular for the assignment of addresses in networks that are based on TCP / IP protocols.

p0010<nplcit id="ncit0002" npl-type="s"><text>A. Bierman, K. McCIoghrie: "Physical Topology MIB and Discovery Protocol Proposal; draft-bierman-pTOPO-mib-proto-00.txt" 'IETF INTERNET DRAFT 25 March 1997, pages 1-38</text></nplcit>, Discloses the use of a "Management Information Base" for use with network management protocols in the Internet. Objective is the identification of physical links between two network ports.

p0011The invention is based on the object of providing an improved method for assigning an IP address to a device. The invention is further based on the object, a corresponding digital storage medium to provide apparatus and a switch.

p0012The basis of the invention will be attained with each of the features of the independent claims. Preferred embodiments of the invention are specified in the dependent claims.

p0013The invention provides a method for assigning an IP address is provided to a device, wherein an identifier of the port to which the device is attached, is transmitted from the switch to the device. The identifier of the port is then transmitted from the device to an address server, the device assigns an IP address based on the identifier of the port. This method is applied when the device has not received "own" identity.

p0014Of particular advantage here is that the elaborate filtering of data packets, as is required in the prior art for detecting the DHCP requests through the switch is omitted. Thus, the switch is released and it can efficient switching mechanisms such as used, for example, cut-through in the switch.

p0015This is especially advantageous for applications in automation technology, especially for Industrial Ethernet and realtime Ethernet. In particular, the invention allows efficient network management of Ethernet applications in the industrial sector, which often have a very large number of nodes.

p0016For example, a defective device can be replaced by a replacement unit, without fear of manual intervention in the network management. The assignment of the IP address to the replacement device can be done automatically without any user interaction.

p0017According to a preferred embodiment of the invention, the identifier of the port is transmitted to the device connected to the port using a neighbor discovery protocol. Suitable for this is in particular the LLDP protocol IEEE802.1AB to STANDARD. Using the mechanisms of the Slow protocol (STANDARD IEEE803.1) LLDP provides neighborhood information in switched networks. This neighborhood information is used to uniquely address.

p0018According to a preferred embodiment of the invention, the assignment of an IP address after the DHCP protocol. After the DHCP protocol to allocate the IP address to a device by the device itself is initiated by the device sends a corresponding DHCP request to a DHCP address server. This DHCP request includes the identifier of the port to which the device is connected, as a basis for the assignment of the IP address to the device.

p0019According to a further preferred embodiment of the invention, the Discovery and Configuration Protocol (DCP) is used. Unlike DHCP case the assignment of IP addresses is not initiated by the terminal, instead by a DCP address server. This asks the device in question the identification of the port to which the device is connected, from to associate on this basis the IP address of the device.

p0020For the operation described above, there are, for example, two variants:<ol><li>a) It is determined that a device is to be connected to a specific port of a switch. Is it not connected, the DCP address server polls the switch with the question: "Who is connected to port x". Reports of the Switch "none" will continue to be polled. Reports of the switch device xyz, so this device is provided with an address and a name. Of particular advantage is that there is less traffic on the network, because only unicasts are used.</li><li>b) It is determined that a device is to be connected to a specific port of a switch. Is it not connected, the DCP address server polls the potentially present device with a DCP Multicast with the question: "Who is connected to port x". Reports to any further polled. be notified by the device xyz, so this device is provided with an address and a name. Of particular advantage is that the switch must be known only to his PortID via LLDP.</li></ol>

p0021Furthermore, preferred embodiments of the invention with reference to the drawings in more detail. Show it:<dl id="dl0001"><dt>figure 1</dt><dd>a block diagram of an embodiment of a network according to the invention,</dd><dt>figure 2</dt><dd>a flowchart of an embodiment of a method according to the invention,</dd><dt>figure 3</dt><dd>a block diagram of an embodiment of a network.</dd></dl>

p0022<figref idrefs="f0001">figure 1</figref> shows an automation system 100. The automation system 100 has a communications network 102, such as an Ethernet. To the network 102 includes a plurality of coupling nodes, called switches, of which a switch 104 in the<figref idrefs="f0001">figure 1</figref> shown by way of example.

p0023The switch 104 has a processor 106 for executing a computer program 108. The computer program 108 stored in the usual way on a digital storage medium such as a memory. The switch 104 has several ports, of which ports 110, 112, 114 by way of example in the<figref idrefs="f0001">figure 1</figref> are shown. Each of the ports of the switch 104 has a port identifier that is also referred to as port ID.

p0024At the port 110 an automation device 116 is connected. The automation device 116 may be, in principle, to any device of automation technology, such as a transducer, a drive, a controller or the like.

p0025The automation device 116 has a processor 118 for executing a computer program 120. The computer program 120 is stored in a known manner on a digital storage medium such as a memory.

p0026An address server 122 is connected via the network 102 to the port 114 of the switch 104th The address server 122 is used for the assignment of Internet Protocol (IP) addresses to the participants of the automation system 100th

p0027The procedure for assigning an IP address to the automation device 116 is as follows:

p0028After connecting the automation device 116 to the port 110, the programmable controller 116 receives from the port 110 whose port identifier 124. The port identifier 124 is stored in the automation device 116th The port identifier 124 is then transmitted from the programmable controller 116 via the switch 104 and the network 102 to the address server 122nd Based on the port identification code 124 of the address server assigns the automation device 116 to its IP address.

p0029This method can be used in the initialisation of the automation system 100, to associate all of the subscriber of the automation system an IP address. A particular advantage of this method is that it can also be applied when replacing a defective device.

p0030If, for example, the automation device 116, so it will be replaced by a corresponding functional automation device 116th Through the connection of the replaced automation device 116 to the port 110 to allocate the IP address is retriggered.

p0031The algorithm for allocation of IP addresses is doing the same result as when assigning the IP address to the original automation device 116, since the algorithm based on the same port identifier is performed 124th

p0032For transmitting the port identification code 124 from the switch 104 to the automation device 116 is preferably a so-called neighbor discovery protocol is used. Such neighbor discovery protocols are known per se from the prior art. With the help of a neighbor discovery protocol takes an automatic exchange of data between neighboring devices instead of on a network.

p0033Preferably, the proximity detection is performed by LLDP, according to Standard IEEE802.1AB (see website http://www.ieee802.org/1/pages/802.1ab.html). With LLDP, each Ethernet station supplies (DTE) his name (chassis ID) and the transmitting port (port ID). Using the mechanisms of the Slow protocol (IEEE803.1) LLDP provides neighborhood information in geswitchen networks.

p0034For transmitting the port identification code 124 from the automation device 116 to the address server 122 preferably comes DHCP is used. In this case, it is in the address server 122 to a so-called DHCP server. After the DHCP protocol, the PLC 116 sends a DHCP request to the address server 122 to request the assignment of an IP address. The port identifier 124 is transmitted as part of the DHCP request from the automation device 116 to the address server 122, the IP address of the programmable controller allocates on this basis 116th

p0035Alternatively comes DCP used. In this case, it concerns with the address server 122 to a print server. Notwithstanding the initiative DHCP to assign the IP address of the automation device 116, but by the DCP address server 122 itself goes out. In response to a request of the DCP address server 122. answers the automation device 116 with the data stored in the automation device 116 port identifier 124. On this basis, the DCP address server 122 will then make the assignment of the IP address to the automation device 116th

p0036Preferably LLDP is used in conjunction with DHCP and Option 82nd Since via LLDP each device knows its neighbors, this information can be used for unique addressing. If the network 102 DHCP is used, the DHCP address server 122 stores in addition to the client ID or host ID and the neighborhood information to an IP address. Prompts for example, the automation device 116 from the DHCP address server 122 an IP address, so it fills the optional 82 designated field with the chassis ID and Port ID received from the neighbors, that is, the switch 104 (ie, for example, port identifier 124). This completely the elaborate filtering of DHCP requests in the switches is omitted, but the DHCP address server 122 can still about the topology information, ie, the port identifier 124, assign an IP address.

p0037Of particular advantage is that a device is replaced, for example, in case of failure of the automation device 116, without a programmer, exchangeable storage medium, such as MMC, or intervention at the DHCP address server 122 is possible. Furthermore, LLDP is a cost to be realized Protocol. Because of the switches of the automation system 100 can be implemented cost-effectively with the same performance.

p0038If in the considered network 102 DCP used as stores of DCP client, that is, for example, the automation device 116, next to the station name, that is the client ID, the neighborhood information. For DCP compared to the direction DHCP for address assignment is reversed. For example, searches the DCP address server 122 when needed for a particular active automation device, such as the automation device 116th

p0039He can carry out this search either via the station name, client ID, chassis ID or neighborhood information. Finds the DCP address server 122 the desired device 116, the assigned IP address is assigned.

p0040As a variant, but can also neighborhood information are the DCP address server specified 122nd In this case, may be omitted searching via station name, client ID or chassis ID, since the neighborhood information for further procedures is sufficient.

p0041As a variant, only the name of the station, client ID and chassis ID is the DCP address server 122 specified. In this case, the search will be performed by the automation device 116 over the name of station, client ID and Chassis ID and the stored neighborhood information.

p0042During the commissioning phase, 100 Station name, client ID and chassis ID must be accessible to the automation devices of the automation system. These are used in addition to search. If the desired automation device found, the local neighborhood information is read and stored in the DCP address server 122nd

p0043In this embodiment is of particular advantage that instead of a DHCP address server a much more cost-effective DCP address server is used. This embodiment is particularly suitable for smaller automation systems with a relatively small number of participants.

p0044The <figref idrefs="f0002">figure 2</figref> shows a corresponding flow chart. In step 200 takes place during commissioning of the automation system, the allocation of IP addresses to the participants of the automation system. In step 202 falls during operation of the automation system from one of the automation devices.

p0045In step 204 the defective automation unit is replaced by being connected to the same port on the same switch as the original automation device. In step 206 the port identifier from the switch is transferred to the replacement unit. This is preferably done by a neighbor discovery protocol. In step 208 the port identifier of the replacement device is transmitted to a server address. This occurs for example by DHCP or DCP. In step 210 the assignment of the IP address to the replacement device is performed by the address server.

p0046Preferably, the steps 206, 208 and 210 in the same manner also in the commissioning phase of the automation system, that is, in the step 200 is performed. This means that the steps are repeated 206-210 for the replacement device during operation of Automatisierüngssystems 100, the allocation algorithm for the IP address to the same conclusion, since the port identification code has not changed.

p0047In another different application scenarios of the present invention will be exemplified:

Scenario 1:

p0048All devices have received their identifier (ID) and are turned on. After switching on the device sending a DHCP request with the identifier to the DHCP server. This assigns the client in response to its unique IP address.<tables id="tabl0001" num="0001"><table frame="all"><title>Principle:</title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="38mm" /><colspec colnum="2" colname="col2" colwidth="46mm" /><colspec colnum="3" colname="col3" colwidth="17mm" /><thead valign="top"><row><entry>identifier</entry><entry>Alias</entry><entry>IP</entry></row></thead><tbody><row><entry>Client1.Anlage1.Werk1</entry><entry>Port1.Client2.Anlage1.Werk1</entry><entry>10.0.0.1</entry></row><row><entry>Client2.Anlagel.Werk1</entry><entry>Port3.Client1.Anlage1.Werk1</entry><entry>10.0.0.2</entry></row><row><entry>Client3.Anlage1.Werk1</entry><entry>Port1.Client2.Anlage1.Werk1</entry><entry>10.0.0.3</entry></row><row><entry>...</entry></row></tbody></tgroup></table></tables>

Scenario 2:

p0049In a running system, a client is exchanged. This is taken from the stock and does not know his identifier. He uses the port identifier of its neighbor, which is stored as an alias for the client in the DHCP server. For example, over the also deliverable from DHCP server "hostname" is replaced by the new client's identifier and stores retentive for further use.

Scenario 3: (DCP):

p0050There will be a system constructed in which all neighborhoods and the connection point of the engineering system (ES) are known. After switching on the voltage no client has an identifier. The Project System (Engineering System (ES)) knows to be issued identifiers and looking over LLDP its direct neighbors. Is this Identifies, so he is baptized over as DCP with its identifier. The client with the identifier is this about LLDP on to its immediate neighbors. Thus this can be addressed via the ALIAS described in Scenario 2 and also be baptized. This snowballed the whole LAN / partial LAN / "baptized" the entire neighborhood.

Scenario 4: (with DHCP):

p0051There will be a system constructed in which all neighborhoods and the connection point of the engineering system (ES) are known.

p0052After switching on the voltage no client has an identifier. The ES knows to be issued identifiers and looking over LLDP its direct neighbors. Is this Identifies, so he is "baptized" via eg DCP with its identifier:

p0053The client with the identifier is this about LLDP on to its immediate neighbors. Thus this can be addressed via the ALIAS described in Scenario 2 via DHCP their IP address and their identifier. This makes the whole LAN / partial LAN / the whole neighborhood is baptized snowballed.

Scenario 5: (DCP):

p0054It is a production machine / will be several series machines built in for a series machine all neighborhoods and the connection point of the engineering system (ES) are known.

p0055With the process described in Scenario 3 is equipped with a "touch" the entire machine to individualize. This is possible with little effort a fast start. In addition to the ES, this task can also be acquired by a PLC or a simple Taufgerät.

p0056The <figref idrefs="f0003">Fig. 3</figref> shows an example of a corresponding network topology.