FR2872982A1 - Computer data transmitting method, involves utilizing power line routing protocol adapted to power line network, for encapsulation of computer data, initialization of power line adapters and routing of data - Google Patents

Abstract

The method involves utilizing a power line routing protocol adapted to power line network, for encapsulation of computer data, initialization of power line adapters and routing of the data. The data is routed by the adapters acting in an autonomous manner for establishing a routing table in order to transport the data from a section of LAN to a real recipient on another section of the LAN. An independent claim is also included for an installation for transmitting computer data from a LAN.

Description

Method and installation for transmitting computer data of a

  local network, using a power line network

  The invention relates to a method of transmitting computer data of a local network, using a carrier current network, and the corresponding installation.

  A local area network (LAN) is a computer network in which data is transported by conventional means, such as Ethernet. Such a network (LAN) is generally segmented into several physically distinct parts, connected by a carrier current network (PLN) in which the data is transported on the carrier current. The carrier current is generally the mains electricity (230 V, 50 Hz in France).

  To allow the passage of computer data between a local area network (LAN) and a carrier current network (PLN), it is known to use access points applying the HomePlug protocol. These access points make it possible to transit computer data from one network (LAN) to another (PLN). They consist of passive PLC modems.

  A local network can be installed in a building, a store, a hotel or even a village, for example, to provide a connection to the global network at different points.

  The first technical problem that arises is that of the distance to be traveled on the carrier current network. To increase this distance, there are several solutions.

  The first is to use two products chained by their Ethernet ports. This chaining causes the removal of access to the powerline network, requires the use of two different encryption keys and involves determining the fixed location of installation of the repetition function.

  The second is to use different frequency bands. In this case, it is necessary to define a fixed point of repetition and to use a specific demodulator-injector. The selection of frequency bands by energy differences and line matching then presents difficulties.

  The third is to use a fixed repetition function, which imposes a specific demodulator-injector and determination of the fixed location of the repetition function.

  An object of the present invention is to overcome the constraints of existing solutions to extend the coverage of a local network using a powerline network.

  Another object of the invention is to provide an optimization of the dynamic bandwidth taking into account the significant variations in impedance and noise on the powerline network.

  The present invention relates to a method for transmitting computer data of a local area network (LAN), using a carrier current network (PLN) and access points (PLA) each incorporating a passive PLC modem, characterized in that that it uses a protocol (PLRP) of dynamic routing / relaying adapted to the current-carrying networks, to carry out the following operations: - encapsulation of the computer data in packets before transmission of the local network (LAN) to the current network (PLN) and de-encapsulation after transmission of the carrier current network (PLN) to the local area network (LAN), - initialization of the access points (PLA) by identification of the other access points (PLAs) present on the same carrier current network (PLN) ), obtaining their mac-address and their communication quality, - routing of computer data by access points (PLA) acting autonomously to establish a routing table in order to route r data from one part of the local area network (LAN) to the actual recipient of another part of the local area network.

  According to other features, encapsulation includes the assignment of a header common to all types of data packets, the header common to all types of data packets includes the addresses of the data packets. send and receive points (PLA) of the packet and the type of the packet, - in the case of relaying, the header also includes the addresses of the end-user access points (PLA) and originating transmitter of the packet, - during the initialization operation, each device (PLA) establishes a global quality matrix of the qualities and mac addresses of the local access points, - the access points (PLA) exchange their global quality matrices to have a view of the complete topology of the carrier current network, - the routing table is established according to the travel time between the access points (PLA) of origin and destination, to determine the shortest journey time.

  The invention also relates to a facility for transmitting computer data of a local network, using a carrier network and access points each incorporating a passive PLC modem, characterized in that each device (PLA) comprises in in addition to a microprocessor / memory / flash unit implementing a protocol (PLRP) dynamic routing / relaying suitable for powerline networks, to ensure the transmission of data.

  Other features appear from the following description given with reference to the accompanying drawings in which: Figure 1 shows the block diagram of a power adapter device (PLA) according to the invention; Figure 2 shows the principle scheme of electing local masters in all access points (PLA); Figure 3 shows the header common to all encapsulated computer data packets prior to being sent on the carrier current network (PLN); FIG. 4 shows the structure diagram of a restricted data packet (LAN DATA) transmitted by one apparatus of the local area network (LAN) to another through the carrier current network (PLN) and Figure 5 shows the structure diagram of a broadcast data packet (LAN-BROADCAST-DATA) transmitted from one local area network (LAN) device to all others.

  The computer data transmission installation according to the invention comprises a local area network LAN, a PLN carrier network and AC line access points, called PLA, providing the interface between the LAN and the carrier line network. PLN, and allowing the passage of computer data from one to another.

  These PLA access points (FIG. 1) comprise on the one hand a passive modem implementing the functions of the HomePlug protocol, on the other hand a microprocessor / memory / flash unit ensuring the implementation of the PLRP protocol, or a routing / relaying protocol. dynamic adapted to powerline networks.

  The main features of the PLRP protocol are as follows: - dynamic data relay between two PLA access points that are not visible, thanks to the addition of one or more PLAs acting as relays, - routing dynamic data by choosing the best access points, - the global administration of all access points from a single point of entry of the local area network LAN, - the global vision of communication qualities between all access points, - management of PLN bearer access authorizations from the LAN, s - management of the communication bandwidth from one LAN LAN point to another.

  The access points implementing the PLRP protocol, called PLA, are endowed with intelligence, unlike the access points implementing the HomePlug protocol, which are passive. The PLRP protocol uses the HomePlug protocol as a communication base on the PLN bearer network.

  The processing of computer data by PLA access points is based on the principle of encapsulation.

  1. Encapsulation 1.1. Principle All data received from the LAN to the PLN is encapsulated by the PLRP protocol before being sent to the PLN. Similarly, any data received from the PLN to the LAN is de-encapsulated before being transmitted over the LAN. Any packet received from the PLN that is not encapsulated by PLRP is discarded. At the same time, PLRP administration packets containing no data from or for the LAN are used on the PLN. The description of the encapsulation and administration data of PLRP will be made with reference to FIGS. 3 to 5. The encapsulation comprises the allocation of a header common to all the PLRP packets, plus data specific to the data type. encapsulated.

  1.2. PLRP Common Header Each PLRP packet sent on the PLN contains a header common to all packet types. This is the PLRP_HEADER.

  It contains, among other things: É Destination Address (DA): address of the packets PLA Source Source (SA): address of the PLA that sent the packet É Type: the type of the encapsulated PLRP packet Final Destination Address (FDA): the PLA final recipient of the packet, in 5 cases of relaying (the one that must deliver it on the LAN) Original Source Address (OSA): the PLA originally transmitting the packet, in case of relaying (the one that took it from the LAN) 1.3. Restricted data (unicast) The restricted data is that transmitted from a LAN device to another device on the LAN through the PLN. These data are of "unicast" type, that is to say, restricted, from one PLA to another PLA. They are encapsulated in a PLRP packet of type LAN_DATA. The added data added for a LAN_DATA is a loop counter, to avoid any possibility of looping between the relays. In the event of communication failure between relay PLAs and if topologies are redefined independently, loopback may theoretically occur. This counter can detect it.

  1.4. Broadcast Data The broadcast data is that transmitted from a LAN device to all other LAN devices through the PLN. These data are of the "broadcast" type. They are encapsulated in a PLRP packet of LAN BROADCAST DATA type. The own data added for a LAN_BROADCAST_DATA is a packet identifier, called BID (Broadcast IDentifier), which allows broadcasting of the broadcast packet across all PLAs without repetition of the data on the LAN or looping between local masters (described later with reference to Figure 2).

  The first phase of the PLRP protocol is initialization. 2. Initialization 2.1. Principle Each PLA implementing the PLRP protocol starts with an initialization phase. This phase is called "topology discovery". This phase aims to discover all the PLA present on the PLN, obtain their MAC address or unique identifier on 6 bytes used by the Ethernet protocol, and their communication qualities. Communication quality represents the reliability of a link from one PLA to another. It is an asymmetric two-dimensional matrix, because the quality of PLA1 to PLA2 may not be the same as that of PLA2 to PLA1. Some PLAs are out of reach because of their physical remoteness or excessive disruptions that interfere with communications. These PLA are called "non-local". PLAs that are seen live, without the help of a relay, belong to the same "local group". The matrix of the qualities / address-mac of the local PLA given by the protocol HomePlug is called PQM (Partial Quality Matrix) or Partial Quality Matrix. The matrix of macaddress qualities of all PLNs on the PLN, obtained during the initialization phase, is called the Global Quality Matrix (GQM).

  2.2. Hello The first step is to send a PLRP packet called HELLO. It is broadcast in "broadcast powerline" mode, that is to say in general broadcast on carrier current to all PLA visible locally, and therefore only local PLA receive it. The HELLO package contains the list of PLA addresses seen through the HomePlug module, as well as their quality. The qualities transmitted are those of the HomePlug (from 38 to 519) brought to a scale of 1 to 254. The addresses are in the form of mac-addresses. This list is the PQM and is limited to 15 PLA entries, due to the current limitation of the HomePlug modem. Each PLA receiving HELLO retrieves the information contained: If it learns which PLA it can see locally, even if they are not in the list of addresses given by its HomePlug component, it completes its GQM to have thus a complete vision of his local group.

  As long as a PLA has not received HELLO, it continues to issue all Thello typically every 2 seconds. If a PLA receives a HELLO that modifies its current GQM, it returns a HELLO again after TnewHello, typically from 0.1 to 0.2 s. If no HELLO has been received during Thello, the PLA moves on to the next phase: election of a local master.

  2.3. Election of a Local Master For each local group, each PLA knows which other PLAs are present and which has provided the information. The one (or those) who has the greatest direct visibility (the largest neighborhood) identifies himself as "local master". Figure 2 illustrates an example with two local groups (A B C D E F) and (E F G H I). E and F are eligible as local master. If two or more masters are eligible for the same local groups, the one with the highest mac address wins the election. No information is exchanged between the PLA for the election: as locally they all share the same GQM, so the result of the election is the same for all.

  2.4. Exchange of the GQM Once the local masters designated, they exchange their respective GQM through MASTER_GQM type packets, diffused in "broadcast powerline" or general diffusion on carrier current. Each master receiving the GQM of others can thus complete his GQM and have a more complete vision of the topology of the network. A MASTER_GQM packet contains the GQM of the sending master as a two-dimensional quality matrix, with mac-addresses as coordinates. If a master receives a MASTER_GQM that modifies its current GQM, it returns a new MASTER_GQM after TnewMasterGQM, typically from 0.1 to 0.2 s. If no MASTER_GQM has been received during TmasterGQM, typically 2 s, the masters move on to the next phase: final release of the GQMs.

  2.5. Final broadcast of the GQM This step aims to disseminate the final GQMs established by the local masters to all other PLA. The masters broadcast their GQM by a packet of the type SLAVE_GQM sent in general broadcast on carrier current. These packets contain the final GQM as a two-dimensional quality matrix, with mac addresses as coordinates (such as MASTER_GQM). If no SLAVE_GQM has been received during TnewSlaveGQM, typically 6 s, the PLA are getting out of the initialization state: they now have in their GQM a view of the complete topology of the PLN network, with all PLA present and the qualities link between them.

  The next phase or PLRP protocol is the phase of stable operation. 3. Stable operation (routing) 3.1. Principle The routing step is the stable phase of the protocol, ie postinitialization. All PLAs have a complete knowledge of the network topology. They can now act autonomously: Routing the data from one part of the LAN to the real recipient of another part of the LAN É calculate a global routing table, with determination of the relays É detect the disappearance of a PLA 3.2 . Routing broadcast LAN or broadcast data from one part of the LAN to all other parts of the LAN The broadcast data received from the LAN is broadcast in bearer broadcast to each PLA of the local group in a LAN_BROADCAST DATA packet. Receiving PLAs disencapsulate them and broadcast them on their part of the LAN. If a PLA is a local master, it also rebroadcast the PLRP packet in powerline broadcasts, in order to reach other local groups. However, it will throw it (no replay on the PLN or the LAN) if it has already broadcast a LAN_BROADCAST DATA packet with the same BID. This BID cache is valid during TBip, typically 5 s.

  3.3. Routing of LAN or Restricted LAN Unicast Data Each PLA maintains a PLA LAN address / MAC address mapping table. This makes it possible to know which PLA to send the encapsulated LAN data to route through the PLN to the final destination of the LAN. Any data coming from the LAN and routed through the PLN makes it possible to match the address-mac device sourceladresse-mac PLA source on all PLA traversed. If a LAN address / PLA address pair is not in the PLA cache to find the recipient, the packet is sent in LAN_BROADCAST DATA to reach all parts of the LAN and therefore its currently un-localized recipient. During the initialization phase, the cache is inactive and all LAN data is sent in LAN_BROADCAST_DATA. Each entry of the cache has a validity limited to TLANCache, typically 300 s, this time base being reset each time a broadcast data corresponds to this entry. Each unicast package contains a loopback counter. It is the PLA that introduces the packet on the PLN that fills the packet field to its current counter value. If a relay sees more than once a packet with the same source and a counter value that is lower or equal, then a loopback exists. The packet is then discarded and the relay goes into the topology discovery phase (sending a HELLO). Encapsulating the data to be transmitted on the PLN with PLRP headers decreases the MTU, or maximum size of a packet that can be transmitted over a network (LAN or PLN) payload. Indeed, the MTU of the PLN is the same as that of the Ethernet, namely 1500 bytes. Therefore, data from the LAN can only be transmitted in a single packet if its size does not exceed MTU (PLN) - max (size (PRLP header)), ie 1460. If LAN data exceeds this size they will be routed through the PLN in 2 fragmented packets: this is fragmentation. Leaving the PLN towards the part of the destination LAN, these 2 fragments will be reassembled to reform the original LAN datum.

  3.4. Relay A relay allows either to send data to a PLA that does not belong to the local group of the transmitter, or to improve the quality of transmission via PLAs that have a better quality of communication than the recipient. final belonging to the same local group. A packet that has to go through a relay is transformed in the following way: DA is changed to the address of the relay PLA SA is changed to the address of the PLA which is relay and which rebroadcasts the packet E FDA and OSA are never modified: they are used to find the final destination of the package, and to complete the LAN address / address PLA 3.5 caches. Routing Table In order to determine which routes and relays to use, each PLA independently establishes a routing table. This table is a list of entries composed each of: É the PLA addressee the relay PLA or relay through which it is necessary to pass to reach the recipient PLA For each destination, we look at the best transmission qualities to reach the PLA. A PLA not reachable live from one point to another has a quality of O. The goal is to find the best combination. The unit of comparison is the transmission time from one PLA to another, which is the inverse of the quality: T = 1 / Q. Each PLA-PLA segment by which the route passes adds the corresponding time to obtain a total time of route of the road. The shortest time determines the best route from an originating PLA to a live destination PLA or through relays. This also implies that the travel time can be shorter via relays than live from one PLA to another. It is a relay of optimization. The routing table is recalculated every Theartbeat (see 4.3.6), typically 15 s.

  3.6. Heartbeat In order to signal its continued presence on the PLN, each PLA sends a HEARTBEAT type PLRP packet to all Theartbeat. This package is composed of the same data as a HELLO packet, ie the local qualities given by the HomePlug interface. It is broadcast in broadcast to the local group. The HEARTBEAT allows not only to signal that a PLA is still present, but also to refresh the GQM PLA of the local group. If a PLA has not received the HEARTBEAT from another PLA of the local group, it is either: É the missing PLA has disappeared io the PLN is physically broken between the two PLA É localized and temporary disturbances prevent communication In order to overcome this last problem and not to declare the remote PLA as nonexistent, three unicast pings are sent to this PLA, at the rate of one every second. At the first ping that receives a response, the remote PLA is again declared visible. If the 3 pings fail, the remote PLA is declared non-existent and we go into the topology discovery phase (sending a HELLO).

  FIG. 3 represents the structure of a PLRP header, with DA (48 bits): MAC address of the destination PLA of the packet SA (48): MAC address of the source PLA of the packet É VLAN_ETYPE (16) : ethertype VLAN; indicates that the package contains a VLAN extension; set to 0x8100 VLAN_TCI (16): priority and VLAN ID; all PLRP packets have a priority of 5, except for LAN_DATA and LAN_BROADCAST_DATA that have priority 0 ETYPE (16): ethertype PLRP; type of Ethernet data used; set to Ox08ff E VERSION (4): version of the protocol; here version 1 E FLAGS (4): options of the package o FRAG (bit 0): fragmentation option; the data to be transported is larger than 1460 (Ethernet MTU - max header size 5 PLRP) Active: the packet is fragmented, and other pieces follow E inactive: unfragmented packet or last packet of fragmentation into course o HEAD_FRAG (bit 1): indicates that the packet is the first of a fragmentation in progress E active: this packet is the first fragment of a fragmented transmission E inactive: this packet is not the first fragment of a fragmented transmission 1s o ENCRYPT (bit 2): encryption option of the active ^ packet: the packet data is encrypted in AES128 E inactive: the data is not encrypted É TYPE (8): type of transported data o 0x00: reserved o 0x01: LAN_DATA o 0x02: LAN BROADCAST DATA o 0x03: HELLO o 0x04: HEARTBEAT o 0x05: MASTER_GQM o 0x06: SLAVE GQM o 0x07-0x09: reserved o OxOa: ADMIN REQUEST o OxOb: ADMIN ANSWER FDA (48): address- PLA mac of final destination to the LAN; used by the relays to find the actual destination E OSA (48): MAC-address of the originating PLA which has introduced the LAN packet on the PLN; used by relays for routing and address tables PLA / LAN-MAC address SEGN (8): HomePlug subnet segment number (0 by default) É RESERVED (24): reserved for future use PLRP HEADER header: 36 bytes.

  Figure 4 shows the structure of a LAN-DATA restricted broadcast data packet, with: COUNTER: 32-bit counter to allow relays to detect possible loops. It is positioned by the original PLA of the packet.

  Figure 5 shows the structure of a broadcast data packet (LAN-BROADCAST-DATA) with: E BID: Randomly selected 32-bit packet identifier. It allows relays not to relay the packet again if they have already processed it, or to broadcast the data on the part of the destination LAN several times. It is filled by the original PLA of the package.

  This packet is always sent in general broadcast on carrier current.

  A HELLO signal includes a 36-byte PLRP header and a HELLO DATA data packet of 1 to 106 bytes, with the following in the data: lo COUNT (8 bits): number of entries in the following 2 lists (maximum 15) É ADDRESS (48): mac address of the first entry É ADDRESS (48): mac address of the last entry É QUALITY (8): quality of the first entry É QUALITY (8): quality of the last entry Ce packet is always broadcast in bearer broadcast.

  A HEARTBEAT signal consists of a 36-byte PLRP header and a HEARTBEAT DATA data packet of 1 to 106 bytes, with in the data: É COUNT (8 bits): number of entries in the following 2 lists (maximum 15) É ADDRESS (48): mac address of the 1st entry É ADDRESS (48): mac address of the last entry É QUALITY (8): quality of the 1st entry É QUALITY (8): quality of the last entry This packet is always sent in general broadcast on carrier current.

  A MASTER_GQM signal comprises a 36-byte PLRP header and a MASTER_GQM DATA data packet of 1 to 1460 bytes, with 25 data in the following: E LINE_COUNT (8 bits): number of rows in the next array É COLUMN_COUNT (8) : number of columns of the following matrix É LINS ADDRESS (48): mac-address of the first line entry É LINE_ADDRESS (48): mac address of the last line entry É COLUMN_ADDRESS (48): mac address of the first entry column É COLUMN_ADDRESS (48): mac address of the last column entry É QUALITY (8): 1st quality of the 1st line of the matrix É QUALITY (8): last quality of the 1st row of the matrix É QUALITY (8) : 1st quality of the 2nd row of the matrix É QUALITY (8): last quality of the last row of the matrix This packet is always sent in general broadcast on carrier current.

  A SLAVE_GQM signal consists of a PLBC header of 36 bytes and a data packet SLAVE_GQM DATA of 1 to 1460 bytes, with in the data: É LINE COUNT (8 bits): number of rows of the following matrix É COLUMN_COUNT (8) : number of columns of the following matrix É LINE ADDRESS (48): mac-address of the first line input É LINE ADDRESS (48): mac-address of the last line entry É COLUMN_ADDRESS (48): mac-address of the lère column entry É COLUMN_ADDRESS (48): mac address of the last column entry QUALITY (8): the 1st quality of the 1st row of the matrix É QUALITY (8): last quality of the matrix row E QUALITY ( 8): 1st quality of the 2nd row of the matrix É QUALITY (8): last quality of the last row of the matrix This packet is always sent in general broadcast on carrier current.

  The PLRP protocol described is specific to online carrier currents. It makes it possible to dynamically define whether a PLA device, for a communication towards a given point, must be a repeater to ensure said communication.

  It also acts as a bandwidth optimizer by its routing protocol, which allows to know if a destination must be reached directly or relayed. Each network PLA device knows whether to reroute data packets automatically. The network topology is refreshed every 15 sec, providing PLA access points in the network with knowledge of access points removed from the network or installed on the power line network, and communication qualities.

  LAN Local Area Network PLN Power Line Network PLC Power Line Coupler PLA Power A PLRP Adapter Power Line Routing Protocol HomePlug is a registered trademark of the HomePlug consortium

Claims (8)

  A method of transmitting computer data of a local area network (LAN), using a carrier current network (PLN) and access points (PLA) each incorporating a passive PLC modem, characterized in that it uses a dynamic routing / relaying (PLRP) protocol adapted to carrier-current networks, for carrying out the following operations: encapsulation of the packetized computer data before transmission of the local area network (LAN) to the carrier current network (PLN) and decapsulation after transmission of the carrier network (PLN) to the local area network (LAN), - initialization of the access points (PLA) by identification of the other access points (PLAs) present on the same carrier current network (PLN), obtaining their mac-address and their communication quality, - computer data routing by access points (PLA) acting autonomously to establish a routing table in order to route the data of a part of the network to the local (LAN) to the actual recipient of another part of the local network.   2. Method according to claim 1, characterized in that the encapsulation comprises the allocation of a header common to all types of data packets.   3. Method according to claim 2, characterized in that the header common to all types of data packets comprises the addresses of the sending and receiving points of the packet (PLA) and the type of the packet.   4. Method according to claim 3, characterized in that, in case of relaying, the header further comprises the addresses of the access points (PLA) final recipient and originator of the packet.   5. Method according to claim 1, characterized in that, during the initialization operation, each device (PLA) establishes a global quality matrix of the qualities and mac-addresses of the local access points.   6. Method according to claim 5, characterized in that the access points (PLA) exchange their global quality matrices to have a view of the complete topology of the carrier current network.   7. Method according to claim 1, characterized in that the routing table is established as a function of the travel time between the access points (PLA) of origin and destination, to determine the shortest travel time.   8. Installation for transmitting computer data of a local network, using a powerline network and access points each incorporating a passive PLC modem, characterized in that each device (PLA) further comprises a microprocessor / memory block / flash implementing a dynamic routing / relaying protocol (PLRP) adapted to bearer networks, to ensure the transmission of data.