BRIEF DESCRIPTION OF THE DRAWINGS
The above and other features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 illustrates an example of a configuration of a Fast Mobile IPv6 network;
FIG. 2 illustrates an example of a flow diagram of a handover process in the network of FIG. 1;
FIG. 3 illustrates a flow diagram of another example of a handover process in the network of FIG. 1;
FIG. 4 illustrates an example of a configuration of a mobile Ethernet network;
FIG. 5 illustrates a flow diagram of an example of a handover process in the network of FIG. 4;
FIG. 6 illustrates an example of a configuration of a bridged portable internet network according to an embodiment of the present invention;
FIG. 7 illustrates an example of a flow diagram of a registration process of a mobile terminal in the network of FIG. 6;
FIGS. 8
a and 8b illustrate examples of flow diagrams of a data transmission process in the network of FIG. 6; and
FIGS. 9
a and 9b illustrate examples of flow diagrams of a handover process in the network of FIG. 6.
DETAILED DESCRIPTION
Hereinafter, embodiments of the present invention are described with reference to the accompanying drawings. In the following description, the same elements are designated by the same reference numerals although they are shown in different drawings. For the purposes of clarity and simplicity, a detailed description of known functions and configurations incorporated herein is omitted as it may make the subject matter of the present invention rather unclear.
In general, Ethernet is one of many technologies that can be easily accessed when transmitting data between different terminals or many users. Such a layer 2 Ethernet technology has been under discussion on the expansion of its area from LAN to WAN/MAN owing to its success. In a WiBro network representing next-generation wireless communication network as an example, the present invention enables a service area covered by existing equipment of layer 3 or more to be served in layer 2 so that management can be facilitated and fast handover service is possible.
FIG. 6 illustrates a configuration of a bridged portable internet network, according to an embodiment of the present invention. Referring to FIG. 6, the network according to the present invention is connected in a mesh structure to form a core network. Further, the network includes: edge bridges 611, 612, 613 and 614 and a branch bridge 615, each of which are configured as layer 2 switches; a plurality of Radio Access Stations (RASs) 621, 622, 623 and 624 appropriately connected to one of the plurality of edge bridges 611, 612, 613 and 614 to provide portable internet services to Mobile Nodes (MNs) within the range of services; a Neighbor Discovery Server (NDS) 616 for supporting the neighbor discovery of all network components and for managing configuration information thereof. The respective MNs (PSS) 631, 632, 633 and 634 are appropriately connected to the corresponding RASs 621, 622, 623 and 624. As an example, a state where the fourth edge bridge 614 is connected to a Correspondent Node CN 712 through a router 711 on the Internet 70 is illustrated in the network of FIG. 6.
In the present invention, a handover faster than Fast Mobile IPv6 is supported, and a new protocol is provided that is capable of solving all the problems of an optimal path, which are problems in Mobile Ethernet. To this end, the entire network is configured such that layer 2 switches are connected in the shape of a mesh as shown in FIG. 6, and each of the bridges 611 to 615 always maintains an optimal path to a specific bridge through a protocol similar to a routing protocol such as IS-IS. Thus, all the Media Access Control (MAC) frames are always transmitted to their destinations via optimal paths within the network. Further, each of the edge bridges 611 to 614 transmit the MAC frame transmitted by a terminal connected to the edge bridge itself by performing MAC in MAC encapsulation. At the time, each of the edge bridges 611 to 614 searches the Destination Address (DA) area of the MAC frame to set the DA area of a new MAC in MAC frame header as the ID (MAC address) of the edge bridge to which a corresponding CN is connected. All the branch switches within the mesh network search the DA area of an outer MAC to switch frames. The edge bridge, having received the MAC in MAC frame having its own ID as an outer DA, deletes the outer MAC and transmits the original MAC frame to the corresponding terminal. Further, an NDS 616 of the Mobile Ethernet is used for expandability in a resilient bridge WiBro network according to the present invention.
FIG. 7 illustrates a flow diagram of a registration process of a mobile terminal in the network of FIG. 6. In the present invention, a mobile terminal (PSS) sends a registration request message to an NDS to register the ID of a bridge connected to its own MAC address and its own IP address in the initial connection to an RAS as shown in FIG. 7. The NDS maintains a table of such registration information. Each table entry has a lifetime, and is maintained in an active state through a periodic registration message before it expires.
The detailed operation is now discussed with reference to FIG. 7. In a state where a link between a PSS and an RAS is formed (step 701), the PSS first sends a registration request message to a corresponding edge bridge connected thereto through the corresponding RAS (step 702). Accordingly, the corresponding edge bridge performs MAC in MAC encapsulation with the frame destination address of the registration request message as the NDS to transmit it to the NDS (step 703), and the frame destination address is finally transmitted to the NDS via another edge bridge within the mesh network (step 704). Accordingly, the NDS stores (and updates) the MAC address of the corresponding PSS, the ID of the corresponding relative edge bridge and the IP address of the corresponding PSS (step 705). Thereafter, in order to inform that a registration is successfully accomplished, the NDS sends a registration response message (e.g., ICMPv6 Neighbor Advertisement message) to the PSS through the edge bridge (step 706), and the corresponding edge bridge performs MAC in MAC encapsulation with the frame of the registration response message (step 707), and then transmits it to the corresponding PSS (step 708).
At this time, the registration request message may be message “ICMPv6 Neighbor Solicitation” for detecting a duplicated address. Since message “ICMPv6 Neighbor Solicitation” originally has a broadcasting address, it is sent to the entire network. In order to prevent this, an edge bridge adds a new MAC header to the corresponding message (MAC in MAC encapsulation) to set a DA area as the MAC address of the NDS and then transmits it. Branch bridges identify only the outer MAC DA of the frame to switch the flame. Further, the NDS recognizes and generates a MAC in the MAC frame.
FIGS. 8
a and 8b illustrate examples of flow diagrams of a data transmission process in the network of FIG. 6. FIG. 8a illustrates an example of the data transmission process in accordance with a temporal flow of message transmission, and FIG. 8b illustrates an example of the data transmission process on a network configuration view. Further, a mobile terminal (CN) transmitting data is connected to a fourth edge bridge and a state where an MN is connected through a second edge bridge is illustrated as an example in FIGS. 8a and 8b.
Referring to FIG. 8a, first, a CN intending to transmit data sends the message “Neighbor Solicitation” to the NDS through a corresponding edge bridge (i.e., the fourth edge bridge) so as to obtain the MAC address (M2) of an MN at a destination (steps 801 and 802). Accordingly, the NDS retrieves the MAC address (M2) of the MN to send the message “Neighbor Advertisement” to the corresponding CN (steps 803 and 804). The CN, having obtained the MAC address (M2) of the MN through message “Neighbor Advertisement,” transmits a frame (steps 804 and 805), and an edge bridge (e.g., the fourth edge bridge) having received the frame performs MAC in MAC encapsulation of the corresponding frame to the ID of the edge bridge through which the MN is connected.
That is, each edge bridge maintains the MAC address of each MN and a BridgeID binding table as a soft state. An edge bridge, having received a MAC frame that will be transmitted to a specific MN, identifies the BridgeID of the corresponding MN in its own table (step 806). If the BridgeID of the corresponding MN exists in its own table, the edge bridge immediately performs MAC in MAC encapsulation with the corresponding BridgeID to transmit it (step 807). Unless the BridgeID of the corresponding MN exists in its own table, the edge bridge sends a BridgeID request message to the NDS (step 808) to obtain the BridgeID of the corresponding MN (step 809), and then performs MAC in MAC encapsulation with a frame to transmit it (step 810). The frame transmitted by being MAC in MAC encapsulated is forwarded the edge bridge (e.g. the second edge bridge) of the corresponding destination MN (step 812), and is MAC in MAC decapsulated at the corresponding edge bridge.
FIG. 8
b illustrates a state where a CN transmitting data is connected to the fourth edge bridge through a router of an external internet as an example. Referring to FIG. 8b, if the CN transmits data to the IP address (IP2) of a destination MN (process 1), the corresponding router obtains the MAC address (M2) of the corresponding destination MN from the NDS through a process that follows Address Resolution Protocol (ARP) (process 2). Thereafter, the destination address (M2) of the MN is added to the header of a corresponding frame to forward the frame to a corresponding edge bridge (i.e., the fourth edge bridge) connected thereto (process 3). The edge bridge (i.e., fourth edge bridge) connected to the router receives the frame to perform MAC in MAC encapsulation of the corresponding frame with the ID (B2) of the edge bridge to which the corresponding MN is connected. At this time, the corresponding edge bridge identifies the BridgeID (B2) of a corresponding MN, which will be transmitted to its own table. If the BridgeID (B2) exists in its own table, the corresponding edge bridge immediately performs MAC in MAC encapsulation with the corresponding BridgeID (B2) to transmit it (process 4). Unless the BridgeID (B2) exists in its own table, the corresponding edge bridge sends a BridgeID request message to the NDS to obtain the BridgeID of the corresponding MN (process 3), and then performs MAC in MAC encapsulation of a frame to transmit it (process 4). The frame, transmitted by being subjected to the MAC in MAC encapsulation in such a manner, is forwarded to an edge bridge (e.g., the second edge bridge) of the corresponding destination MN (process 4), and is MAC in MAC decapsulated to be provided to the MN (process 5).
In a case where a router obtains the MAC address (M2) of a corresponding destination MN from the NDS in the data transmission as described above, the NDS stores the BridgeID (B4) of an edge router (i.e., the fourth edge router) to which the corresponding router will be connected as the ID of an edge router of the CN for the MN in a table. In a case where the corresponding MN performs a handover after the BridgeID (B4) has been stored in the table in such a manner, the BridgeID (B4) can be functionally used.
FIGS. 9
a and 9b illustrate examples of flow diagrams of a handover process in the network of FIG. 6. FIG. 9a illustrates the handover process in accordance with a temporal flow of message transmission, and FIG. 9b illustrates the handover process on a network configuration view. Further, a mobile terminal (MN) performing a handover is connected to the second edge bridge, and a state where a CN is connected through the fourth edge bridge is illustrated as an example in FIGS. 9a and 9b.
Referring to FIGS. 9a and 9b, the NDS first receives a BridgeID request message sent by each edge bridge to previously store a BridgeID list of the CN for a specific MN in the data transmission process shown in FIGS. 8a and 8b. In such a state, the MN, for example, moving (performing a handover) from the second edge bridge to the third edge bridge, forms a link with the third edge bridge (step 901 of FIG. 9a and process 0 of FIG. 9b), sends a registration request message to the NDS through the third edge bridge to register a new BridgeID (B3) connected to the MN itself (steps 902 and 903 of FIG. 9a and process 1 of FIG. 9b). Accordingly, the NDS sends an update message containing the BridgeID (B3) of a new edge bridge of the MN to an edge bridge (i.e., the fourth edge bridge) corresponding to the BridgeIDs (B4) of CNs having been previously stored in a list of the corresponding MN within the table (step 904 of FIG. 9a and process 2 of FIG. 9b) such that the edge bridge (the fourth edge bridge) can immediately perform MAC in MAC encapsulation to the new edge bridge (the third edge bridge). The NDS sends a registration response message to the MN through the third edge bridge (steps 905 and 906 of FIG. 9a). Further, the NDS sends a BridgeID update message containing the BridgeID of the CN to the new edge bridge (the third edge bridge) of the corresponding MN such that the corresponding edge bridge can immediately perform MAC in MAC encapsulation (step 907 of FIG. 9a). If the MN transmits data in such a state (step 908 of FIG. 9a), the data is transmitted to the fourth edge bridge via the third edge bridge, and is then transmitted to the CN (steps 909 and 910 of FIG. 9a). Further, if the CN transmits data to the MN (step 911 of FIG. 9a and processes 3 and 4 of FIG. 9b), the data is transmitted to the third edge bridge via the fourth edge bridge, and is then transmitted to the MN (steps 912 and 913 of FIG. 9a and processes 5 and 6 of FIG. 9b).
The numbers of signaling packets of Fast Mobile IPv6 (FMIPv6) which is an existing handover protocol, Mobile Ethernet, and a protocol according to the present invention, are as shown in the following Table 1.
TABLE 1
|
|
FMIPv6
Mobile Ethernet
Proposal
|
|
|
Signaling
Router Solicitation for Proxy
H/O
Registration
|
Packets
Advertisement
|
per
Proxy Router Advertisement
Recommendation
Request
|
handover
Fast Binding Update
Context Transfer
Registration
|
Fast Binding Acknowledgement
Context Transfer
Response
|
Handover Initiate
Ack
BridgeID update
|
Handover Acknowledgement
Registration
(to MN's bridge)
|
Binding Update
Request
BridgeID update
|
Binding Acknowledgement
Registration
(to CN's bridge)
|
(Neighbor Advertisement
Acknowledgement
(Context Transfer)
|
Acknowledgement)
Update Entry
(Context Transfer
|
(Neighbor
Cancel Entry
Ack)
|
Advertisement)(broadcast)
|
Total
9 or 11
7
4 or 6
|
|
Referring to Table 1, in a case of the Fast Mobile IPv6, there is required the exchange of 9 signaling packets in a basic condition. If NCoA generated by a terminal is not valid in a case of operating in a reactive mode, there is required the exchange of 11 signaling packets. At this time, one of them is a broadcast message. Further, the number of binding update messages is in proportion to that of CNs.
In a case of the Mobile Ethernet, there is required the exchange of 7 signaling packets, and it is constant regardless of the number of CNs. However, since the message “Update Entry Request” is sent to all the segment gate switches along a ring in a case of an inter-segment handover, a large number of network resources are consumed. Further, other signaling packets except binding update and binding response messages are exchanged only among a PAR, an NAR and an MN in the Fast Mobile IPv6. On the other hand, signaling packets of the Mobile Ethernet requires a great deal of round-trip time, and the number of “Update Entry” and “Cancel Entry” messages is increased in the inter-segment handover.
The protocol according to the present invention requires the exchange of signaling packets, i.e., 4 to 6 signaling packets, less than those in the two existing schemes as shown in Table 1.
As described above, a bridged portable internet system and a method of processing a signal thereof, according to the present invention, performs a simple and effective signaling process using a layer 2 bridge in a next-generation wireless edge network so that an effective and fast handover can be provided.
While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Patent Application
20080002625
