KR100434913B1 - Home agent selection method in mobile host support from multicasting environment - Google Patents

Abstract

In the multicast routing supporting mobile hosts, the present invention selects one of the mobile nodes belonging to the multicast group so that only the home agent of the designated mobile node can tunnel the multicast datagram so that packet redundancy and traffic The present invention relates to a method for selecting a home agent in a mobile host supporting multicast environment to prevent excessiveness.

To this end, the present invention provides a method for selecting a home agent of GGSN / FA for multicast in a mobile IP environment, and forwarding one of a plurality of home agents of a plurality of mobile terminals to which the GGSN / FA joins a multicast group. A first step of designating an agent; Determining whether the home agent is a forwarding agent when a multicast message reception request signal is received from the home agent; A third step of receiving a multicast message if the home agent is a forwarding agent as a result of the determination of the second step, and rejecting the multicast message if the home agent is not a forwarding agent; And a fourth step of forwarding the multicast message received from the forwarding agent to a multicast group member, and assigning a forwarding agent for multicast to GGSN / FA to solve the multicast traffic duplication problem. In addition, by designating a backup forwarding agent in the GGSN / FA, it provides an effect of minimizing packet loss as the mobile terminal of the forwarding agent moves between networks.

Description

Home agent selection method in mobile host support from multicasting environment}

The present invention relates to a method for selecting a home agent in a mobile host supporting multicasting environment. In particular, in the routing of multicasts supporting a mobile host, one of the mobile nodes belonging to a multicast group is selected. The present invention relates to a method for selecting a home agent in a mobile host supporting multicast environment, in which only a home agent of a designated mobile node can tunnel multicast datagrams, thereby preventing packet redundancy and traffic congestion.

In general, the transmission method of the Internet can be divided into unicast, broadcast, and multicast from the perspective of a sender and a receiver participating in the transmission.

Among them, the multicast transmission method is a method in which one or more senders transmit data to a specific one or more receivers, and is employed in the field of Internet video conferencing technology.

The difference between multicast transmissions and general unicast Internet applications lies in their transmission packets.

In general, an Internet application program over Transmission Control Protocol / Internet Protocol (TCP / IP) transmits a packet by indicating the Internet address of a receiver to which the sender of the data is to be received in the header of the transmission packet.

However, for multicast transmission, the packet is transmitted by indicating the group address of the receiver instead of the receiver's address in the header.

The group address for multicast transmission is a D-class IP address (224.0.0.0 to 239.255.255.255). Unlike the A, B, and C-class IP addresses that represent individual Internet hosts around the world, they do not represent actual hosts. For example, the receiver receiving the multicast packet having the group address determines whether the packet belongs to the group of the packet and determines whether to accept the packet.

However, since most routers on the Internet currently support only unicast, in order to transmit multicast packets, encapsulated packets are transmitted by using the concept of tunneling between multicast routers.

That is, the same method as the existing unicast packet when passing through general routers that do not support multicast by routing the IP packet of both ends of the tunnel set between the multicast routers before the data packet header having the multicast address. It can be routed back to the end of the tunnel and finally sent to the end of the tunnel.

In order to perform IP multicast communication, there are two basic protocols, IGMP (Internet Group Management Protocol) that manages a group of hosts that perform multicast communication, and a multicast routing protocol that controls routing of multicast packets.

Firstly, IGMP is a protocol defined in a network, and is a protocol for notifying a router (multicast router) address of a multicast group to be transmitted to a router (multicast router) in which a host in the network supports multicast communication.

The multicast router sends only packets destined for the advertised multicast group. By using IGMP, resources can be used more effectively because unnecessary multicast packets are not transmitted in the network.

Second, the multicast routing protocol is a protocol between multicast routers that route transmission of multicast packets to effectively use resources between networks.

In multicast communication, since the path for transmitting to one multicast group generally varies depending on the transmitting host, more complicated control is required than the path control in unicast communication.

As a multicast routing protocol, the IETF considers Distance Vector Multicast Routing Protocol (DVMRP), Multicast Open Shortest Path First (MOSPF), and Protocol Independent Multicast (PIM).

On the other hand, the recent research and development of IP multicast considering the mobile host to support the mobile host has been actively made.

However, even in the IP multicast considering the mobile host, there is a problem that the load is increased at the network level by transmitting the packet data by the conventional unicasting method.

Accordingly, the present invention has been proposed to solve the above problems of the prior art, and a main object of the present invention is to select one of the mobile nodes of the multicast group corresponding to the function of the GGSN / FA, and to designate the home agent of the mobile node. In the mobile host support multicast environment, only the tunneling of multicast datagrams is allowed, thereby preventing excessive traffic due to multicast datagram tunneling from the home agent of all terminals in the multicast group. A method of selecting a home agent is provided.

In addition, another object of the present invention is that there is no clear procedure to delete registration in the mobile IP, so that the mobile node can no longer receive the multicast datagram due to the move to the mobile node, resulting in packet loss. The present invention provides a method for selecting a home agent in a mobile host supporting multicast environment, which minimizes packet loss by providing a backup home agent for each backup.

In order to achieve the above object, the present invention provides a method for selecting a home agent of a GGSN / FA for multicast in a mobile IP environment, wherein the GGSN / FA joins a multicast group. A first step of designating one of the home agents of the forwarding agent; Determining whether the home agent is a forwarding agent when a multicast message reception request signal is received from the home agent; A third step of receiving a multicast message if the home agent is a forwarding agent as a result of the determination of the second step, and rejecting the multicast message if the home agent is not a forwarding agent; And a fourth step of forwarding the multicast message received from the forwarding agent to a multicast group member.

1 is a schematic diagram showing a support procedure of a mobile host in a mobile IP environment.

2 is a diagram illustrating a packet transmission process to a mobile host in a mobile IP environment.

3 is a network diagram of a mobile host support multicast environment according to an embodiment of the present invention;

4 is a flowchart illustrating a method for selecting a home agent in a mobile host support multicast environment according to an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10a, 10b, ....... 10n: Mobile terminal

20: UMTS Terrestrial Radio Access Network (UTRAN)

30: packet switch (SGSN)

40: Gateway / External Agent (GGSN / FA)

50a, 50b, ........ 50n: Home Agent

Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings. In general, a host may use the same IP address even if the host moves within a connected network. However, when a host moves between networks, the moved host cannot communicate unless it uses a new IP address whose network part is the address of the moved network.

Mobile IP is a protocol that automatically detects movement between networks of a host and enables communication in the same manner as the network before the movement even in the network after the movement.

Mobile IP supports three types of host location detection, location registration, and packet transmission to a moved location, thereby realizing the movement between hosts' networks. Mobile IP also supports mobility, which introduces a new entity called the Mobility Agent.

A mobile agent can be referred to as a router in a broad sense in that it performs location management or packet transmission of a moving host between networks, and processes packets going to a mobile host.

In addition, the mobile host has two IP addresses, namely, a constant IP address (home address) irrespective of movement and an IP address (care of address) that changes with movement. The combination of the home address and the care of address is called a binding.

Also. The network determined by the network portion of the mobile host's home address is called the home network of the mobile host, and the network to which the mobile host leaving the home network is currently connected is called a visiting network.

Furthermore, the mobile agent connected to the home network of the mobile host is called the home agent of the mobile host, and the mobile agent connected to the network to which the mobile host is connected after the movement is called a foreign agent.

1 is a schematic diagram illustrating a support procedure of a mobile host in a mobile IP environment.

As shown in Fig. 1, a mobile agent (home agent) advertises a message (agent advertisement message) including a network address of a network to which it is connected at regular intervals. The mobile host determines the address of the current network by receiving an agent advertisement message.

When the mobile host moves to a different network, it receives a new agent advertisement message containing a different network address. As a result, the mobile host detects that the mobile host has moved to another network, and sets the IP address of the mobile agent (external agent) as the care of address of the mobile host.

Furthermore, the mobile host notifies the mobile agent (the external agent) and the home agent of the mobile host where the binding changed by the mobile is moved, and performs location registration. In FIG. 1, the mobile host directly registers a location with a home agent. However, the mobile host may register a location with a home agent through an external agent. By this procedure, the binding of the mobile host is always managed by the home agent and the foreign agent.

2 is a diagram illustrating a packet transmission process to a mobile host in a mobile IP environment.

As shown in Fig. 2, the host communicating with the mobile host is not notified of the binding of the mobile host and always transmits the packet with the home address of the mobile host as the receiving side.

This packet is sent to the home network of the mobile host, which the home agent receives on behalf of the mobile host.

Next, the home agent adds (encapsulates) an intercepted packet after adding (encapsulating) a new IP header (IP encapsulation header) that uses the mobile host's care of address as a receiver using binding of the mobile host.

Since the care of address of the mobile host is that of the foreign agent of the mobile host, this transport packet is received by the foreign agent.

The foreign agent removes the encapsulation header from the received packet and sends it to the mobile host which is the original receiving party. As such, the mobile host receives packets of the same format no matter where it moves.

Also, when the mobile host sends a packet to a communication partner, the home address is always used as the sender address. For this reason, a packet of the same format is received regardless of the movement of the mobile host to the communication counterpart of the mobile host.

As such, from end to end, the communication of the mobile host can be performed smoothly by performing the same packet format regardless of the location.

On the other hand, if the mobility support scheme in the unicast environment described above is applied to the multicast environment as it is, it can handle both the transceiver's mobility, guarantee the continuity of the packet to some extent, and support the mobile multicast with minimal modification. There is an advantage that this is possible.

However, as mobile terminals distributed in different networks within the same group move to one network, the end points of the tunnels are concentrated in one FA, which may cause packet duplication problems on the FA side. .

In addition, when the FA of the newly moved network is already subscribed to the multicast group, a case may occur in which data transfer by the tunnel from the HA and transfer by the FA from the upper router of the multicast tree overlap.

In addition, when the FA side of the newly moved network has a shorter routing path from the sender than the HA, it is caused by a triangle and is similar to that of the unicast environment, and the scalability problem is the same multi in one HA. Although the number of mobile terminals belonging to the cast group increases, the scalability is greatly reduced by performing the unicast transmission as many as the number of mobile terminals through the tunnel despite the multicast data.

3 is a diagram illustrating a network configuration in a mobile host support multicast environment according to an embodiment of the present invention.

As shown in FIG. 3, the UMTS includes a Core Network (CN) formed by a Gateway GPRS Support Node (GGSN) 30 and a Serving GPRS Support Node (SGSN) 40.

There is also a UMTS Terrestrial Radio Access Network (UTRAN) 20. A mobile terminal (MT) 10 communicates with the UTRAN 20 via an air interface.

The mobile terminal 10 is a terminal that supports GPRS and provides a Mobile IP function. The mobile terminal may connect terminal equipment, a notebook, or a PDA. The base station (UTRAN) UMTS Terrestrial Radio Access Network (UTRAN) 20 includes base station and control station functions, and the base station and the mobile terminal have a radio interface.

The Serving GPRS Support Node (SGSN) 30 serves as a local IP switch.

The gateway / external agent 40 provides a function of combining a Gateway GPRS SupportNode (GGSN) defined in GPRS and a Foreign Agent (FA) defined in Mobile IP. The gateway acts as a gateway that connects to the Internet, and the external agent acts as an agent that provides local Mobile IP services.

The home agent 50 is located in the public Internet, not in the GPRS network, and is an agent that assigns an address to and manages a mobile terminal provided with an initial Mobile IP service.

A home agent selection method in a mobile host supporting multicast environment according to an embodiment of the present invention will be described in detail with reference to FIG. 3 as follows.

When the mobile terminal 10 joining the multicast group moves between networks, the mobile terminal 10 requests the GGSN / FA 40 to join the group using a wireless interface. There are two types of messages used here: report and query.

The GGSN / FA 40 receiving the group join report message manages the list of mobile terminals 10 having membership in the group, and uploads the newly requested mobile terminal 10 to the group list.

Meanwhile, when there are a plurality of mobile terminals 10 joining the group, the GGSN / FA 40 selects the home agent 50 of one mobile terminal 10 as a forwarding agent.

The GGSN / FA 40 selects another mobile terminal among the mobile terminals 10 joining the group as a backup up forwarding agent.

Subsequently, when the multicast message is received, the GGSN / FA 40 determines whether the home agent 50 that forwards the multicast message is a forwarding agent or a backup forwarding agent.

If the home agent forwarding the multicast message is a forwarding agent, forward the multicast message.

The GGSN / FA 40 then forwards the forwarded multicast message to the multicast group members using the forwarding engine.

At this time, if the home agent 50 for forwarding the multicast message is a backup forwarding agent, the multicast message is forwarded to be discarded when a certain time elapses after reception.

On the other hand, when the mobile terminal belonging to the home agent 50 designated as the forwarding agent moves to another network, the GGSN / FA 40 cannot know such a situation because the delete function is not provided from the multicast group list.

Accordingly, when the GGSN / FA 40 has elapsed a certain time after the multicast message arrives from the backup forwarding agent and the multicast message does not arrive from the home agent 50 selected as the forwarding agent, the GGSN / FA 40 sends the home agent 50 a message. It is determined that the mobile terminal 10 belonging to the other network has forwarded the multicast message received from the backup forwarding agent to the multicast group member.

Then, the forwarding agent is designated as the backup forwarding agent, and the home agent 50 of the other mobile terminal 10 is also designated as the backup forwarding agent in the multicast group.

4 is a flowchart illustrating a method for selecting a home agent in a mobile host support multicast environment according to an embodiment of the present invention.

As shown in FIG. 4, the GGSN / FA designates a forwarding agent and a backup forwarding agent among a plurality of home agents to which mobile terminals belonging to the multicast group belong (S110).

Subsequently, when there is a multicast message reception request signal requesting to receive a multicast message from the home agent (S112), it is determined whether the home agent making the reception request is a forwarding agent or a backup forwarding agent (S114). .

As a result of the determination, in the case of the forwarding agent, after receiving the multicast message (S124), the multicast message is forwarded to the multicast group member (S126).

As a result of the determination, in the case of the backup forwarding agent, after receiving the multicast message (S118), it is determined whether there is a message reception from the forwarding agent (S120).

If there is a message reception from the forwarding agent, the multicast message is discarded (S122). If there is no reception of the multicast message from the forwarding agent, it is determined that the mobile terminal has moved to another network and the received multicast message is a member of the multicast group. Forward to (S126).

As described above, the present invention has the effect of solving the multicast traffic redundancy problem by specifying a forwarding agent for multicast in the GGSN / FA.

In addition, the present invention, by specifying a backup forwarding agent in the GGSN / FA has an effect that can minimize the packet loss as the mobile terminal of the forwarding agent moves between networks.

Claims (3)

In the method of selecting a home agent of GGSN / FA for multicast in a mobile IP environment, A first step of designating, as a forwarding agent, one of a plurality of home agents of a plurality of mobile terminals to which the GGSN / FA has joined the multicast group; Determining whether the home agent is a forwarding agent when a multicast message reception request signal is received from the home agent; A third step of receiving a multicast message if the home agent is a forwarding agent as a result of the determination of the second step, and rejecting the multicast message if the home agent is not a forwarding agent; And a fourth step of forwarding the multicast message received from the forwarding agent to a multicast group member. The method of claim 1, Received from a backup forwarding agent when a multicast message is not received from the forwarding agent within a predetermined time by designating one of a plurality of home agents of a plurality of mobile terminals that the GGSN / FA joins a multicast group as a backup forwarding agent. And a fifth step of forwarding the forwarded message to a multicast group member. The method of claim 2, The fifth step, A sixth step of designating, as a backup forwarding agent, one of a plurality of home agents of a plurality of mobile terminals joined by the GGSN / FA to a multicast group; Determining whether the home agent is a backup forwarding agent when a multicast message reception request signal is received from the home agent; An eighth step of receiving and storing a multicast message if the backup forwarding agent is the determination result of the seventh step; Receiving a multicast message from the backup forwarding agent, the GGSN / FA determining whether a multicast message reception request signal is received from the forwarding agent within a predetermined time; A tenth step of forwarding the received multicast message to a multicast group member if the multicast message reception request signal is not received within a predetermined time as a result of the determination of the ninth step; And an eleventh step of designating the backup forwarding agent as a forwarding agent and designating one of a plurality of home agents as a backup forwarding agent.