JP2000253037A - Method for transferring radio packet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the consumption problem of frequency resources by allowing a radio bridge to decide a port other than a root port and a designated port, shifting the state of the port into a suspend state, transmitting a suspend notification signal to a radio bridge and allowing the radio bridge receiving the notification signal to shift the state of the port into a suspend state. SOLUTION: First, a suspend state is newly defined, and when a logical port is decided as neither a root port nor a designated port and when a suspend notification signal is received, it is shifted into a suspend state. In the suspend state transmission of a data packet and a BPDU and transfer of a received data packet to the other ports are not performed. The received data packet is discharged. Also, the reception monitoring of a configuration BPDU is not performed differing from blocking. Further, a radio bridge detects the change of a network topology and shifts from a suspend state to a listening state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a packet transfer method for a wireless packet network. In particular, the present invention relates to a wireless packet transfer method between wireless bridges that performs packet transfer based on a spanning tree protocol (hereinafter, referred to as “STP”).

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of a conventional packet transfer method using STP. The system illustrated in FIG. 7 includes a plurality of LANs (LANA, LANB,
LANC) and wireless bridges (Bridge1, Bridge2, Bridge3) respectively connected to the LAN. The wireless bridge is equipped with an STP, and the wireless bridges are connected to each other by a port via a packet network including a wireless line.

At this time, one of a plurality of wireless bridges
One wireless bridge is defined as a root bridge. The root bridge establishes a packet transfer path between wireless bridges at the top of the root bridge, and enables packet transfer between wireless bridges while preventing transfer packets from looping between wireless bridges. Here, Bridge 1 is defined as a root bridge.

[0004] The wireless bridge has a plurality of ports because the wireless bridge has STP. The ports are classified into three types: a root port, a designated port, and other ports. The classification method is described below.

[0005] First, a method of determining a root port will be described. The network administrator sets path costs for all logical ports of each wireless bridge. The path cost indicates a priority when a port is used, and the smaller the numerical value, the higher the priority.
First, the root bridge periodically updates the Configuration BP
DU (Bridge Protocol Data Unit) is transmitted from all ports. The ConfigurationBPDU has a root path cost as an information element. Next, the root bridge transmits a Configuration BPDU with a root path cost = 0. And C
The wireless bridge that has received the onfiguration BPDU calculates a port root path cost by adding the path cost of the receiving port to the root path cost for each port. Configur
The port having the lowest port root path cost among the ports receiving the ationBPDU is determined as the root port, and the port root path cost is stored as the bridge root path cost.

Next, a method of determining a designated port will be described.
The wireless bridge is a port other than the root port.
The bridge root path cost and the path cost of the port are added. If the port has not received a Configuration BPDU, the port is determined to be a designated port, and the configuration value obtained by substituting the added value for a root path cost.
ationBPDU is transmitted. The port is Configuration
When the BPDU has been received, the added value is compared with the port root path cost of the port. If the added value is small, the port is determined as the designated port, and a Configuration BPDU in which the added value is substituted for the root path cost is transmitted. I do. If the addition value is large, it is determined that the port is neither the root port nor the designated port.

FIG. 8 is a state transition diagram of a port in the STP. In STP, port is in Blocking state, Listen
A transition is made between four states of an ining state, a learning state, and a forwarding state, and a data packet is transferred according to each state.

[0008] After the wireless bridge starts, all ports are
Set to Listening state.

A port in the listening state does not transmit a data packet or transfer a received data packet to another port. If the port is a designated port, BP
DU is transmitted. When the wireless bridge determines that the port is neither the root port nor the designated port,
Transition to the king state. The port in the listening state transits to the learning state after a certain period.

In the port in the learning state, the source MAC address of the received data packet is stored in the filtering database. The transmission of the data packet and the transfer of the received data packet to another port are not performed. If the port is a designated port, the BPDU is transmitted. When the wireless bridge determines that the port is neither the root port nor the designated port, the wireless bridge transits to the Blocking state.
The port in the learning state transits to the forwarding state after a certain period.

In the port in the forwarding state, the source MAC address of the received data packet is stored in the filtering database, the received data packet is transferred to another port based on the filtering database, and
Transmission of received data packets on the port in the Forwarding state based on the filtering database is performed. If the port is a designated port, the BPDU is transmitted. In the case of the designated port, the BPDU received at the root port is transmitted.

A port in the Blocking state does not transmit data packets and BPDUs and does not transfer received data packets to other ports. The received data packet is discarded. When the wireless bridge re-determines the port in the blocking state as a root port or a designated port due to a change in the network topology, the wireless bridge listens to the port.
Transition to the state. BPDU from opposite wireless bridge
Is monitored by a timer, and the BPDU is
If no is received, the state transits to the Listening state.

The Configuration BPDU has a topology change flag. When the root bridge detects a topology change such as disconnection / recovery of a wireless line, addition / deletion of a wireless bridge, a configuration BP for a certain period of time.
Set the topology change flag of the DU to ON, and
Send urationBPDU. Wireless bridges other than the root bridge detect a topology change using the topology change flag (ISO / IEC 10038 (ANSI / IEEE802.1D, 19
93 Edition) MAC Bridges).

[0014]

However, in the prior art, when the network topology is stable, Blocki
The port opposite to the port in the ng state is in the Forwarding state. This is based on the assumption that the prior art is applied to packet transfer between wired bridges.
This is because the AN exists and the packet is transferred to the terminal accommodated in the LAN.

FIG. 9 is a configuration diagram showing an example of transfer of a broadcast packet when the conventional technique is applied to a wired bridge network.

However, for example, the wireless LAN standard
In a wireless bridge network based on IEEE 802.11, wireless bridges are directly connected by a logical wireless line identified by a MAC address unique to each wireless bridge, and no LAN exists between wireless bridges. For this reason, even if a port in the Forwarding state transfers a packet, if the state of the opposite port is Blocking, the transfer packet is all discarded at the receiving port.

FIG. 10 is a configuration diagram of a transfer example of a broadcast packet when the conventional technique is applied to a wireless bridge network. As is apparent from FIG. 10, in a wireless bridge network in which a finite frequency is shared and used by a plurality of wireless lines, useless packet transmission consumes frequency resources, resulting in a decrease in throughput and an increase in transfer delay time. The problem arises.

An object of the present invention is to provide a wireless packet transfer method which solves the problem that a port opposite to a port in a blocking state consumes frequency resources by transmitting useless packets.

[0019]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a packet network having a plurality of LANs and wireless bridges respectively connected to the LANs, and the wireless bridges are connected by wireless lines. The wireless bridge has one or more ports, and the port is connected to the opposite wireless bridge via a wireless line.
(Spanning Tree Protocol) in a wireless packet transfer method for managing the status of each port and transferring data packets transferred between LANs based on the STP, instead of the Blocking state based on the STP, Packet and BPDU (Bridge
Protocol Data Unit) is defined as a Suspend state in which transmission is stopped.
A port other than the root port and the designated port based on the TP is determined based on the STP, and the state of the port is set to Suspend.
To the wireless bridge facing the port.
The wireless bridge that transmits the spend notification signal and receives the Suspend notification signal from the port changes the state of the port to the Suspend state. While the forwarding port in the prior art forwards a packet even when the port opposite to the port is in the blocking state, the Susp.
The end state port is different in that transmission of the packet to the opposite wireless bridge is stopped. This makes it possible to stop transmission of useless data packets and BPDUs, and has an effect of suppressing a decrease in throughput and an increase in transfer delay time due to consumption of frequency resources.

According to another embodiment of the present invention, when the wireless bridge detects a topology change based on the STP, it changes the port from the Suspend state to the Listening state. As a result, it is possible to cancel the suspension of the transmission of the data packet and the BPDU from the Suspend state port, and the tree path can be reconstructed based on the STP.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a system including a plurality of wireless bridges according to the present invention. The wireless bridges are connected by wireless lines, and each wireless bridge has a unique MAC address. The wireless bridge has a logical port (logical port) for each opposed wireless bridge, and identifies each logical port by the MAC address of the opposed wireless bridge.

FIG. 2 shows a packet format communicated between wireless bridges. This is the wireless LAN standard
The packet format for transferring between IEEE802.11 wireless bridges is shown. When receiving a packet, the wireless bridge knows the transfer source wireless bridge from the transmitting station address of the received packet and identifies the receiving logical port. The status of each logical port is managed based on the STP. Note that the port status of the wired port is similarly managed based on the STP.
Wired ports and wireless ports are identified by differences in hardware interfaces.

FIG. 3 is a state transition diagram of the wireless bridge according to the present invention. Unlike the prior art, a Suspend state is newly defined instead of the Blocking state. To the Suspend state,
The transition is made when it is determined that the logical port is neither the root port nor the designated port, and when the Suspend notification signal is received. In Suspend, transmission of data packets and BPDUs and transfer of received data packets to other ports are not performed. The received data packet is discarded. Also, Blocki
Unlike ng, reception monitoring processing of Configuration BPDU is not performed. The wireless bridge detects a change in the network topology by receiving the Configuration BPDU with the topology change flag ON, and transitions from the Suspend to the Listening state.

FIG. 4 is a flowchart of a wireless bridge according to the present invention when a Configuration BPDU is received. If there is a port that is newly determined to be neither a root port nor a designated port, the port is transited to Suspend, and the port is connected to the opposite wireless bridge.
Send a spend notification signal. If a change in the network topology is detected by receiving a Configuration BPDU with the topology change flag being ON, the port in the Suspend state transits to the Listening state. Next, a Configuration BPDU is transmitted from the designated port.

FIG. 5 is a flowchart of a wireless bridge according to the present invention when a Suspend notification signal is received. The wireless bridge transitions the reception port to Suspend.

FIG. 6 is a flowchart of a wireless bridge according to the present invention when a data packet is received. The wireless bridge stores the source MAC address and the receiving port of the received data packet in the filtering database. In the case of a broadcast packet, the packet is transmitted from all ports in the forwarding state except the reception logical port.
In the case of a unicast packet, if the destination terminal address is being registered in the filtering database, the packet is transmitted from a port in a specific 1 Forwarding state based on the filtering database. At this time, if the reception port of the received packet matches the transfer destination port based on the filtering database, the packet is discarded. When the port is not registered in the filtering database, transmission is performed from all ports in the forwarding state except the reception logical port.
It is not transmitted from ports in the Suspend, Listening, and Learning states.

Various changes, modifications and omissions within the scope of the technical idea and viewpoint of the present invention can be easily made by those skilled in the art. The description of the above embodiment is merely an example, and does not limit the present invention. Therefore, the present invention
It is limited only as defined by the appended claims and equivalents thereof.

[0029]

As described in detail above, according to the present invention, transmission of useless data packets and BPDUs is stopped by transitioning the Blocking port and the port facing the port in the prior art to Suspend. It is possible to obtain an effect of suppressing a decrease in throughput and an increase in transfer delay time due to consumption of frequency resources.

Further, by shifting the port in the Suspend state to the Listening state when the topology changes, it is possible to cancel the suspension of the transmission of the data packet and the BPDU from the Suspend port, and the tree route is automatically set based on the STP. An effect that can be reconstructed is obtained.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a system including a plurality of wireless bridges according to the present invention.

FIG. 2 shows a packet format communicated between wireless bridges.

FIG. 3 is a state transition diagram of a wireless bridge according to the present invention.

FIG. 4 is a flowchart of a wireless bridge according to the present invention when receiving a Configuration BPDU.

FIG. 5 is a flowchart of a wireless bridge according to the present invention when a Suspend notification signal is received.

FIG. 6 is a flowchart of a wireless bridge according to the present invention when receiving a data packet.

FIG. 7 is a configuration diagram of a system including a plurality of wireless bridges according to the related art.

FIG. 8 is a state transition diagram of a wireless bridge according to the related art.

FIG. 9 shows a case where the conventional technique is applied to a wired bridge network;
FIG. 4 is a configuration diagram illustrating a transfer example of a broadcast packet.

FIG. 10 is a configuration diagram illustrating a transfer example of a broadcast packet when the conventional technique is applied to a wireless bridge network.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H04L 29/06 (72) Inventor Hitoshi Takanashi 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Stock In-company (72) Inventor Masahiro Morikura 3-19-2 Nishi Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Corporation F-term (reference) 5K030 GA08 HA08 HC14 HD03 HD07 JL01 5K033 CC01 DA17 DB19 5K034 EE03 HH01 HH02 HH63 5K067 AA11 BB21 CC08 DD17 EE02 EE10 FF02 HH17 HH23 KK15 9A001 CC05 CC06 CC08 EE01 KK56

Claims (2)

[Claims] 1. A packet network having a plurality of LANs and wireless bridges respectively connected to the LANs, wherein the wireless bridges are connected by a wireless line, wherein the wireless bridges include one or more wireless bridges. The wireless bridge implements STP (Spanning Tree Protocol), and manages the status of each port based on the STP. In the wireless packet transfer method for transferring data packets transferred between the LANs, a packet and a BPDU (Bri) to the opposite wireless bridge are newly replaced in place of the blocking state based on the STP.
dge Protocol Data Unit) to define the Suspend state to stop transmission, the wireless bridge, among the ports of its own bridge, determines a port other than the root port and the designated port based on the STP based on the STP, The port changes the state of the port to the Suspend state, transmits a Suspend notification signal to the opposite wireless bridge to the port, and the wireless bridge that receives the Suspend notification signal from the port changes the state of the port to the Suspend state. A wireless packet transfer method, comprising: 2. The wireless bridge, when detecting a topology change based on the STP, sets the port to the Su.
The wireless packet transfer method according to claim 1, wherein a transition is made from a spend state to a listening state.