Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L12/00—Data switching networks
  • H04L12/28—Data switching networks characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks]
  • H04L12/46—Interconnection of networks
  • H04L12/4641—Virtual LANs, VLANs, e.g. virtual private networks [VPN]
  • H04L12/467—Arrangements for supporting untagged frames, e.g. port-based VLANs
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/48—Routing tree calculation

Definitions

• the present invention relates to a method of establishing service flow routing constraints in a local network or infrastructure consisting of interconnected bridges.
• Local or infrastructure networks are known that route Ethernet-based service flows either between a first user's equipment and a second user's equipment, or between a first user's equipment and the equipment of a first user.
• several users in the case of point-to-point and point-to-multipoint communications or multipoint-to-multipoint communications, respectively.
• the term network will be used to designate a physical network that is local or infrastructure.
• VLANs Virtual Local Area Network
• a virtual network defines a logical topology of the physical architecture of a network.
• the user equipment subscribers, service providers, professional users, etc.
• the user equipment are first grouped either on the basis of physical criteria such as the MAC (Medium Access Control) address. ) specific to each user equipment, either on the port numbers specific to each user equipment, or on the basis of services such as layer 2, 3 or higher of the OSI model, or on the basis of protocols used by each user equipment to communicate.
• MAC Medium Access Control
• the user equipment of a network is most often interconnected by equipment called bridges.
• the groups of user equipment obtained are interconnected logically between them by these bridges to form a virtual network. It can be noted that a virtual network can also be created for each equipment group. Virtual networks connected by bridges are then obtained.
• bridges of a network allow access to services because they are also connected to one or more groups of equipment and then allow the exchange of service flows between user equipment belonging to this or these groups.
• one of these bridges called the headend bridge, is also connected to a service provider's equipment to provide service flows to the user equipment of all groups.
• Ethernet bridges With reference to the type of service flow frames they carry.
• the virtual network considered thereafter will be a layer 2 virtual network.
• An Ethernet bridge is a device that has a number of ports (at least two) to which user devices or certain other bridges of the network are connected.
• each Ethernet bridge includes a bridge matrix that informs the bridge of the internal link to establish between two (or more) of its ports when a service flow frame is to be transferred from user equipment (or bridge) to another user equipment (or to another bridge). For this, each bridge undergoes a learning phase that allows to know the equipment or bridges that are connected to each of its ports. The transfer matrix then memorizes the relationships between each port and the addresses of the user equipment or bridges that are connected to this port.
• a network can only work if the paths between bridges of the Ethernet frames do not form loops, which occurs when an exchanged frame passes twice through the same bridge. Indeed, when broadcast frames will be sent on such a network, each bridge sends them through all its ports. The frames then circulate in loops and are multiplied each time by a bridge. The frames have no life, so they can turn indefinitely in one of the loops of the VLAN. This is commonly known as the "broadcast storm".
• STP spanning tree protocol
• ISO / IEC 15802-3: 1998 standard IEEE Std 802.1D-1998)
• RSTP Rapid Spanning Tree Protocol
• MSTP Multiple Spanning Tree Protocol
• the STP protocol allows the regular exchange between the bridges of the network of protocol units called BPDUs (Bridge Protocol Data Unit in English) in order to obtain a tree topology of the virtual network or so that a new topology of this virtual network can be determined when an event occurs on the network (connection of a new equipment, rupture of a segment between two bridges, failure of a bridge, ).
• BPDUs Bridge Protocol Data Unit in English
• STP is a Layer 2 protocol, that is, it operates directly at the Ethernet bridges of the network. This protocol is said convergent because from a finite number of exchanges of BPDU units, the role of each bridge network is defined to determine the paths taken by the Ethernet frames.
• the STP protocol is broken down into three successive steps which are respectively an election stage of the root bridge (root bridge in English), a step associating the port attributes and a step of assigning the port states according to the port attribute associations.
• each bridge B 1 of the network is associated with a unique identifier IDB (Bridge Identifier in English).
• Each bridge B also keeps in memory a parameter IDR 1 (Root Identifier in English) likely to take the value of a bridge identifier.
• the identifier IDB 1 of a bridge has two parts: firstly, the priority (expressed on 2 bytes) and, on the other hand, the MAC address of the bridge (expressed on 6 bytes).
• the priority of a bridge is IEEE 802. The default ID is equal for all bridges. However, as we will see later, the administrator may have an interest in defining different priority values according to the bridges.
• Each bridge B 1 of the network then considers that it is the root bridge of the virtual network. Then begins sending a BPDU by one of the bridges of the virtual network, for example by the bridge B 1 , to the other bridges to which it is connected.
• a B 1 + I bridge receives this BPDU.
• the bridge B 1+ ] compares the IDB bridge identifier 1 contained in the received BPDU unit with its parameter IDR 1+ ] and two cases can then occur.
• the bridge identifier IDB 1 received by the bridge B 1 + I has a value lower than that of the parameter IDR 1+ I that it stores, the value of its parameter IDR 1 + I is replaced by the IDB bridge ID 1 received.
• the bridge B 1+ 1 then considers that the root bridge is the bridge B 1 .
• this bridge identifier IDB 1 has a value greater than that of its parameter IDR 1 + I
• the bridge B, + i does not make any substitutions and continues to consider that the root bridge is the one designated by the value of its IDR 1 + I parameter.
• the bridges B 1 of the virtual network By exchanging their IDR parameter values 1 via BPDUs, the bridges B 1 of the virtual network all end up having the same value of parameter IDR, and consequently to elect by common agreement a single bridge to rank root bridge of the virtual network.
• the step of association of the attributes of port begins following the stage of election of the root bridge.
• the purpose of this step is that a so-called port attribute is associated with each port of each bridge of the virtual network.
• the attribute associated with a port defines the role played through this port in the determination of the paths of the Ethernet frames through the virtual network.
• the port attributes that give this port the transfer status are the attributes 'designated' ⁇ designated in English) and 'root' (root). These two terms are to be considered later within the meaning of the IEEE Standard Std 802.1D-2004.
• the attribute associated with this port gives this port the so-called blocking state.
• the port attributes that give this port the blocking state are the 'alternate' (also known as 'backup') attributes.
• the protocol STP associates with each port of the various bridges the attribute is designated (D), is root (R), or alternates (A) which will make it possible to define if this port is in the state of either transfer or blocking.
• the root attribute is associated with a port of each bridge other than the root bridge.
• the port of a bridge is elected to the rank of root port when it is in connection with the root bridge and allows that the exchange of frames between this bridge and the root bridge is the fastest among the possible exchanges between the other ports of this bridge and the root bridge.
• the root port of a bridge is the one that provides the most 'direct' access of this bridge to the root bridge.
• the designated attribute is associated with at least one port of each bridge.
• the root bridge ports are all associated with the 'designated' attribute. We can refer to the IEEE Std standard. 802. ID for more details.
• the ports of each bridge that are not associated with either the root attribute or the designated attribute are associated with the alternate attribute.
• the step of assigning the port states follows the step of associating the port attributes. In this step, each port associated with the designated attribute or attribute root is considered in the transfer state and each port associated with the alternate attribute is considered in the blocking state.
• Fig. 1 is a diagram of an example of a NET virtual network.
• an internal link I 1 ⁇ is here considered as linking a port of a bridge to only one other of the ports of this bridge.
• the present invention is not limited to three-port Ethernet bridges because the only constraint imposed on these bridges is that the number of their ports is greater than or equal to 2.
• Each equipment group comprises a certain number of user equipment of which only two are shown in FIG. 1: the user equipment EUi situated in the group Gi and the user equipment UE 2 located in the group G 2 .
• the equipment group G 5 comprises an equipment E of an operator or service provider. This equipment is intended to provide service flow frames for all user equipment of all equipment groups.
• the topology of the virtual network NET is a ring topology that is to say that each bridge of the virtual network is connected to two other of its bridges.
• This logical topology is used for example when the physical architecture of this network is of the sonet / SDH type.
• This example of topology has been chosen to facilitate the explanations that follow.
• the present invention is not limited to this type of logical topology but can be applied to virtual networks whose topology is more complex than that of FIG. 1, for example when each bridge is connected to more than two other bridges.
• the present invention is not related to the type of the physical architecture because the present invention is in layer 2 of the OSI model while the physical architecture is in layer 1 of this model.
• Fig. 2 represents an example of the NET virtual network following a convergence of the STP protocol.
• the ports Pi 2 , P 2 2 , P 3 , 2 and P 43 are associated with the root attribute R and the ports Pi i3 , P 2j3 , P 3j3 , P 5i 2 and P 5 3 are associated with the designated attribute D.
• the port P 42 which is associated with the alternate attribute A is in the blocking state thus logically opening the loop formed by the ring topology of this virtual network ( the segment 'blocked' between the ports P 4 2 and P 3; 3 is in dotted line in Fig. 2).
• the port of each bridge connecting a user equipment group to this bridge is associated with the designated attribute D so that this port is in the transfer state.
• each port in the transfer state of a bridge B 1 regularly sends a BPDU to the port of another bridge B j to which it is connected.
• This other port can be in the transfer state but also in the blocking state.
• the STP protocol since a port of the bridge B j which is likely to receive at regular intervals these BPDU units no longer receive these units, the STP protocol then considers that an event has occurred on the segment connecting these two ports. and restart a convergence to obtain a new logical topology of the virtual network without taking into account this segment.
• the STP protocol determines that one of the bridges of a virtual network is elected root bridge. It is possible to force the STP protocol to always elect the same bridge as a root bridge. This is useful, in particular, for this root bridge to be the bridgehead of the network. For this, the STP protocol electing the root bridge from the identifiers associated with these bridges and these identifiers being defined, among others from a priority value, the administrator can force this protocol to always elect the root bridge as being the head bridge by assigning the lowest possible priority value to this head bridge.
• the NET network administrator when configuring this network, determines particular paths taken by service flow Ethernet frames by allowing or preventing these frames from being routed through the internal links of the different bridges of the NET virtual network. . Fixed administrator thus constraints called flow of service flow. Once the routing constraints have been defined, the administrator manually configures the transfer matrix Mt 1 of each bridge B, according to the routing constraints chosen, and this, by means of a network manager. According to the example of FIG. 2, each internal link l, k of each Ethernet bridge
• the UEi user equipment can then directly exchange Ethernet frames with the user equipment UE 2 via the bridges Bi and B 2 without their exchanges passing through the headend bridge B 5 on which a
• a service provider may want to connect a device C for controlling flow exchanges between users. This device C is shown in FIG. 2 as being part of the equipment E.
• the network administrator defines service flow constraints that force each exchange of flows to pass necessarily through the headend bridge.
• the STP protocol automatically initiates a new convergence as soon as this event is detected in order to determine a new logical topology of the NET virtual network, that is to say new associations of the port attributes. and determining the states of the different ports of the bridges of the virtual network NET taking into account the break of the segment connecting the bridges Bi and B 5 .
• Fig. 4 represents a diagram of the result of this new convergence of the STP protocol.
• the ports Pi 3 , P 2 3, P 3j3 and P 43 are now associated with the root attribute R and the ports P 2j2 , P 3i2 and P 4; 2 are now associated with the designated attribute D.
• the port Pi 2 now associated with the alternate attribute A is in the blocking state.
• the NET virtual network still does not work despite this new convergence of the STP protocol because the user equipments of the Gi G 2 and G 3 groups no longer have access to the network because of the definition of the routing constraints. It is necessary for the administrator to manually re-define the routing constraints via the network manager as quickly as possible so that users do not have a break in service access that is prolonged.
• the aim of the present invention is to avoid that the introduction of routing constraints in a network makes it tedious for its administrator, the reconfiguration of a virtual network, determined from this network, and causes a loss quality of service when an event occurs on the network.
• the present invention relates to a method of establishing service flow routing constraints in a network of bridges. interconnected between them, said routing constraints defining those internal links between ports of each of said decks whose establishment is prohibited, one of said bridges being considered to be the head-end bridge, said method comprising a step of association of bridge port attributes of the network in which is associated with the port, which provides the most direct access to said headend bridge, a root attribute.
• the method is characterized in that it comprises:
• said port attribute association step of a bridge being executed as soon as an event occurs on said network, said step of obtaining said associations between ports of each bridge and port attributes is preceded by a step detecting the updating of the attributes associated with the ports of at least one of said bridges.
• said step of defining the routing constraints comprises a step of associating the root attribute associated with a port of a bridge with a so-called leading attribute and with each other attribute of a port. a bridge to a subscriber attribute, the establishment of an internal link between two ports of a bridge is then prohibited if one of these two ports is not associated with the head attribute.
• each bridge being associated with an identifier formed inter alia of a priority value
• the bridge which is considered to be the headend bridge is the bridge associated with the identifier whose priority value is the lowest among the priority values of the identifiers associated with the other bridges.
• the present invention also relates to a device for setting service flow routing constraints intended to be associated with an Ethernet bridge of said network subjected to routing constraints.
• the present invention relates to a computer program for establishing service flow routing constraints of an Ethernet bridge of a network subject to said routing constraints.
• the said computer program implements the steps of the above method of establishing.
• FIG. . 1 which represents a diagram of an example of a virtual network
• FIG. 2 which represents an example of the virtual network obtained from the network of FIG. 1 following a convergence of the STP protocol
• FIG. 3 which represents a diagram of the virtual local network of FIG. 2 when routing constraints were imposed during the configuration of this network
• FIG. 4 which represents a diagram of the result of a new convergence of the STP protocol following an event occurring on the network of FIG. 3 according to the state of the art
• FIG. 5 which represents a diagram of the result of a new convergence of the STP protocol following an event occurring on the network of FIG. 3 according to the present invention
• FIG. 6 which is a flowchart of the steps of the service flow routing constraint method according to the present invention
• FIG. 7 which shows a block diagram of a service flow routing setting apparatus according to the present invention.
• the proposed invention is to define service flow routing constraints in a network, based on the port attributes associated with the service ports. each bridge of this network.
• the routing constraints are then re-defined automatically according to rules for establishing internal links between the ports of each of these bridges.
• Fig. 6 is a flow diagram of the steps of the service flow routing constraint method according to the present invention.
• This method is intended to be executed by each bridge of a network as soon as a virtual network has been determined and at each port of each bridge has been assigned either a root attribute R, designated D, or alternating A.
• the method starts with a step 200 of obtaining the associations between attributes and ports of a bridge B 1 .
• step 200 three associations are obtained for each bridge B 1 , in particular the associations between the port Pij and the designated attribute D, the association between the port Pi 3 and the designated attribute D and the association between the Pi 2 port and the R root attribute.
• Step 200 is followed by a step 300 of definition of the routing constraints relating to each bridge.
• each bridge B 1 of the network can be associated with one or more routing constraints.
• step 300 of definition of the routing constraints relating to a bridge B 1 the establishment of any internal link l 1 is prohibited ; k between two ports of a bridge B, if one of these two ports is not associated with the root attribute R.
• the method of establishing routing constraints described above can be used during the configuration of a virtual network, thus avoiding an administrator having to manually configure the transfer matrices of the various bridges of this network.
• the method can also be used when the configuration of a new logical topology of the virtual network, obtained as soon as an event occurs on this network.
• step 200 it is advantageous for step 200 to be preceded by a step 100 of detecting the updating of the attributes associated with the ports of at least one of said bridges.
• Fig. 5 illustrates the result of the execution of the routing constraint setting method according to the example of FIG. 4.
• the link li i which was prohibited according to FIG. 4 is now allowed and the link I] 2 which was previously allowed is now prohibited according to FIG. 5.
• said step 300 comprises a step of associating the root attribute R (associated with a port of a bridge) with a so-called head attribute H ⁇ Head in English and each other attribute of a port of a bridge to a subscriber attribute S (Subsc ⁇ ber in English), the establishment of an internal link between two ports of a bridge being then prohibited if one of these two ports are not associated with the H head attribute.
• each bridge being associated with an identifier formed inter alia of a priority value
• the bridge which is considered to be the headend bridge is the bridge associated with the identifier whose priority value is the lowest among the priority values of the identifiers associated with the other bridges.
• said detection step 100 is implemented by software interrupt.
• Fig. 7 is a block diagram of a service flow routing set-up device D according to the present invention.
• the device D is intended to be associated with an Ethernet bridge B 1 of a network subject to said routing constraints.
• the device D is integrated in the bridge B 1 but, according to another embodiment, the device D can only be associated with the bridge B 1 .
• the bridge B 1 comprises a communication bus B to which are connected means PROC for processing digital data, a nonvolatile memory 15 ROMi a RAM ,, P ports, j associated to COM means for receiving and transmit service flow frames, MTT means 1 for transferring an incoming frame on a port P g to one or more other ports P 1; k and MAP means for associating an attribute with each of its ports and, in particular at the port that provides the most direct access to said head bridge the root attribute R.
• the MAP means implement the STP protocol.
• the bridge B 1 also includes a transfer matrix Mti which stores, on the one hand, the data defining the relationships between equipment (and / or bridges) and ports of this bridge, relationships that it has learned during a phase and on the other hand, the associations between ports of the bridge B, and port attributes determined by the MAP means 1 .
• the device D comprises means MOA for obtaining said associations between ports of the bridge B 1 and port attributes, stored in the transfer matrix Mti and means MDA for defining transport constraints between the ports of the bridge B 1 as a function of the port attributes associated with each bridge port B 1 .
• the means MDA prohibit the establishment of a link between two ports of the bridge B 1 if one of these two ports is not associated with the root attribute R.
• each root attribute R associated with a port of the bridge B 1 is associated with the head attribute H and each other attribute of a port of the bridge B 1 is associated with the attribute d Subscriber S.
• the establishment of an internal link between two ports of a bridge is then prohibited if one of these two ports is not associated with the attribute of head H.
• the non-volatile memory ROM 1 then stores the PRG1 and PRG2 programs and digital data allow, among other things, their implementation. More generally, the ROM 1 is readable by the processing means PROC 1 , integrated or not to the bridge B 1 and can be removable.
• the memory ROM thus stores the associations between port attributes and ports of the bridge B 1 and the data of the transfer matrix Mt 1 obtained, on the one hand, during a prior learning phase and on the other hand the data defining the routing constraints imposed on this transfer matrix.
• the programs according to the present invention are transferred into the RAM RAM 1 which then contains the executable code of the invention as well as the data necessary for the implementation of the invention.
• this program is interrupted and the program PRG2 is launched in order to redefine the routing constraints relating to this port.
• the program PRG1 then resumes its execution as soon as the program PRG2 ends.

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• 2007
  • 2007-07-13 FR FR0705101A patent/FR2918831B1/fr not_active Expired - Fee Related
• 2008
  • 2008-07-11 WO PCT/EP2008/005697 patent/WO2009010243A1/fr active Application Filing
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