1. Field of the Invention
The present invention relates to a mobile node adapted router and a home agent router forming a packet communication system supporting at least mobile nodes among fixed nodes and mobile nodes.
2. Description of the Related Art
As a protocol for mobile nodes enabling communication in an IP network even when nodes change connection points in the network, the Internet Engineering Task Force (IETF) of the U.S. has established the Mobile IP (document [1]: RFC2002) protocol (note: the documents cited in the specification are listed together at the end of the specification).
Due to the rapid rise in the number of nodes serviced by IP networks in recent years, a serious problem has arisen of the depletion of IP addresses. A transition is underway to a network using the IPv6 (document [2]: RFC2460) protocol enabling use of more IP addresses. Therefore, in addition to the Mobile IP protocol in IPv4 networks up to now, effort is being made to establish a Mobile-IPv6 (document [3]) protocol supporting movement of nodes in an IPv6 network. The IETF is engaged in deliberations for the next stage of requests for comments (RFC).
In the Mobile-IPv6 protocol, depending on the configuration of the network or the location of the node, sometimes time is taken for the switching the transfer route when a mobile node (MN) moves. In such a case, there is a problem that if packets are sent from another node to a network connected to before the movement of the mobile node, packet loss occurs and the quality of service deteriorates.
Further, to switch the transfer route, not only the mobile node, but also the correspondent node (CN) communicating with the mobile node has to support the Mobile-IPv6 protocol. Therefore, when the correspondent node does not support the Mobile-IPv6 protocol, the packets to be transmitted to a mobile node are transferred to the mobile node through a home agent router (HA) cooperating with a home link to which the mobile node is normally connected. Therefore, there is a problem of an increase in the transfer delay or concentration of traffic in a home agent router. The above problems will be explained in detail later with reference to the drawings.
An object of the present invention is to provide, in view of the above problems, a mobile node adapted router and home agent router able to shorten the time required for switching a transfer route and increase the speed of switching of the packet transfer route and, for packet transfer from a correspondent node not supporting the IPv6 protocol to a mobile node, to shorten the transfer route and suppress an increase in the packet loss and transfer delay and the concentration of traffic at a home agent router causing deterioration of the quality of service.
To attain the above object, the mobile node adapted router (10) according to the present invention is provided with a memory means (11) for storing a current address of a mobile node which a correspondent node should store instead of the correspondent node and a transfer means (12) for referring to the memory means (11) when receiving a packet transmitted to the home address of the mobile node, converting it to the current address, and transmitting the packet.
Due to this, a router is realized which can shorten the time required for updating a current address of a mobile node to increase the speed of switching of a transfer route and provide a transfer route for a node not supporting this protocol without going through a home agent router each time.
These and other objects and features of the present invention will become clearer from the following description of the preferred embodiments given with reference to the attached drawings, wherein:
Preferred embodiments of the present invention will be described in detail below while referring to the attached figures.
Here, the memory means 11 stores the current address of a mobile node which the correspondent node of the packet communication should store instead of the correspondent node.
Further, the transfer means 12 refers to the memory means 11, converts the home address to a current address, and transmits a packet when receiving the packet transmitted from a correspondent node to the home address of the mobile node.
The home agent router 20 forms a network supporting communication of at least mobile nodes like the mobile node adapted router 10 of
Here, the reception means 21 receives update notifying information transmitted for notifying the home agent router of the updating of an address along with a change in a current address due to movement of a mobile node.
Further, the address update notifying means 22 transmits the current address after updating to another router forming part of the network when receiving the update notifying information.
The home agent router 20 has the function of notifying the current address to the memory means 11 based on the present invention in addition to the ordinary functions of a home agent router. The function of notifying the current address is not limited to this (22) (explained later).
Therefore, since the operation for updating the address after movement of the mobile node which the correspondent node supporting the Mobile-IPv6 should inherently perform is performed beforehand by the mobile node adapted router 10 positioned closer than the correspondent node first, the time required for switching the transfer route is shortened and therefore the problematic packet loss is greatly reduced.
Further, the conventional routine where a packet transmitted from a correspondent node not supporting Mobile-IPv6 to a mobile node passes through the mobile node adapted router 10 to the home agent router where the address is rewritten to the current address of the mobile node and sent to the destination mobile node becomes unnecessary and thus the packet is sent directly from the mobile node adapted router 10 to the destination mobile node without going through the home agent router. Therefore the problems of packet transfer delay and concentration of traffic at the home agent router are greatly alleviated.
The present invention can be applied not only to cases supporting the Mobile-IPv6 protocol, but also cases supporting protocols corresponding to the Mobile-IPv6 protocol. Here, however, the explanation will be made taking as an example supporting the current Mobile-IPv6 protocol mainly.
Therefore, first, before explaining embodiments of the present invention, an explanation will be given of a mobile node adapted router 10 of the related art for facilitating understanding of the present invention. Further, an explanation will be given of a home agent of the related art corresponding to the above home agent router 20.
First, referring to
From this state,
Step [1]: Assume that the mobile node has moved to the network 4.
Step [2]: The mobile node generates an address C as the new CoA in the network 4.
Step [3]: The mobile node sends a binding update (packet notifying CoA: defined in document [3]) to the home agent router and the correspondent node CN1 as the binding update (BU) in the figure to notify them of the CoA (=address C).
Step [4]: Assume that before the binding update (BU) transmitted at step [3] is received by the correspondent node CN1, the packets P1, P2, and P3 are transmitted from the correspondent node CN1 to the mobile node. At this time, the destination address of the packets, that is, the CoA, remains as B.
Step [5]: The home agent router and the correspondent node CN1 receive the binding update (BU) transmitted from the mobile node at step [3] and update the CoA of the mobile node stored as the binding cache from the address B to the address C (A→B, A→C in the figure). Next, the home agent router and the correspondent node CN1 transmit a binding acknowledgment (packet for notifying acknowledgment of reception of binding update, defined in document [3]) over a not shown route to the mobile node.
Next, refer to
At step [4] of
In this example, there are two networks 5 and 6 between the mobile node and correspondent node CN1. When going through more networks, however, the time required from when a binding update (BU) is transmitted from the mobile node to when this is received by the correspondent node CN1 and the CoA is updated (in the above example, steps [3] to [5] of
First, referring to
From this state,
Step [1]: Assume that the mobile node has moved to the network 4.
Step [2]: The mobile node generates an address C as a new CoA in the network 4.
Step [3]: The mobile node transmits a binding update to the home agent router and correspondent node CN2 as shown by “BU” in the figure to notify them of the CoA (=address C). Whether or not the correspondent node (CN1/CN2) supports the Mobile-IPv6, the mobile node sometimes transmits a binding update to the correspondent node (CN1/CN2).
Step [4]: The packets P5 and P6 transmitted from the correspondent node CN2 to the home address (=A) of the mobile node are transferred in the network 2. A correspondent node not supporting Mobile-IPv6 transmits the packets to the home address A of the mobile node at all times.
Step [5]: At step [3], the home agent router and correspondent node CN2 receive the binding update (BU) transmitted from the mobile node. The home agent router stores this as the binding cache. The CoA for the mobile node is updated from B to C (in the figure, A→B, A→C). The correspondent node CN2, however, does not support the Mobile-IPv6 protocol, so it is not possible to process the received binding update. That is, the correspondent node CN2 does not store the CoA (=address C) of the mobile node MN.
Note that the home agent router receiving the binding update returns a binding acknowledgment to the mobile node MN by a not shown route.
Next, refer to
At step [4] of
Here, the packet P5 is tunneled to the CoA before updating (=address B), so is not received at the mobile node and therefore becomes packet loss. On the other hand, the packet P6 is tunneled to the CoA after updating (=address C) and therefore is received at the mobile node. After this, the packet P7 transmitted from the correspondent node CN2 to the home address A of the mobile node is received by the mobile node through the routers R1→R2→HA→R4. That is, the packets transmitted from a correspondent node not supporting Mobile-IPv6 are always transferred through the home agent router to the mobile node when the receiving mobile node is moving from the home link to an outside link. This causes an increase in the transfer delay of packets, a concentration of the packet traffic in the home agent router, etc. Further, when the mobile node and home agent router are far apart, it takes time to update the CoA in the home agent router in the same way as the case shown in
An embodiment of the present invention for solving these problems will be explained in detail below.
The embodiment according to the present invention shortens the time required for updating the CoA of the mobile node and increases the speed of switching of the packet transfer route. Further, it optimizes the packet transfer route from a correspondent node not supporting Mobile-IPv6 to a mobile node so as not to go through the home agent router each time. Due to this, it becomes possible to prevent an increase in the packet transfer delay and packet loss causing deterioration of the quality of service.
This configuration consists of the configuration of
The registering means 13 newly registers the correspondence between the home address and the current address in the memory means 11 triggered by the reception of update notifying information transmitted for notifying the correspondent node in communication of updating of an address along with a change of the current address due to movement of the mobile node.
This configuration consists of the configuration of
The network 2 includes a home agent router 20 for accommodating a mobile node at its home address.
The registering means 23 newly registers the correspondence between the home address and the current address in the memory means 11 triggered by the transfer of an updated address from the home address router 20 when receiving update notifying information transmitted for notifying the home agent router 20 of updating of an address along with a change of the current address due to movement of the mobile node.
First, referring to
The mobile node adapted router R2 receives a binding update (BU) transmitted from the mobile node instead of the correspondent node CN1 or CN2 (step [1] in the figure). Alternately, the home agent router notifies the mobile node adapted router R2 of the updating of the address, while the mobile node adapted router R2 receives this (step [2] in the figure). Due to step [1] or [2], the COA (current address) for the mobile node is stored (step [3] in the figure).
Among the correspondent nodes, the correspondent node CN1 supports Mobile-IPv6. The binding update from the mobile node is received at the mobile node adapted router R2 and does not reach the correspondent node CN1. Therefore, the correspondent node CN1 does not know that the mobile node is moving outside of the home link. Therefore, not only the correspondent node CN2 not supporting Mobile-IPv6, but also the correspondent node CN1 transmits a packet to the home address (=address A) of the mobile node.
In this case, to transmit the binding update (BU) from the mobile node to the home agent router HA and the correspondent node CN (CN1/CN2) and transmit the binding acknowledgment from the home agent router or correspondent node to the mobile node, it is necessary to establish authentication information by an authentication header (document [4] RFC2402) between the mobile node and home agent router and between the mobile node and correspondent node. This information is comprised of a security parameter index, authentication algorithm, authentication key, etc.
When there is no such authentication information, no binding update is transmitted from the mobile node, so the router R2 of the figure cannot update the CoA from the binding update of step [1]. In this case, as shown at step [2] of the figure, it is effective to notify the CoA of the mobile node from the home agent router HA to the mobile node adapted router R2. Note that notification of the CoA from the home agent router HA to the mobile node adapted router R2 is not defined in the Mobile-IPv6 protocol.
Next, referring to
In this way, the router 10 of the present invention (or the router 10 and router 20) can shorten the time required for updating the CoA of the mobile node and increase the speed of switching of the packet transfer route to the mobile node. Further, when there is a transmission of a packet from the correspondent node CN2 not supporting Mobile-IPv6 to a mobile node, the transfer route is optimized so as not to go through the home agent router each time. Due to this, it becomes possible to prevent an increase in the packet transfer delay or packet loss causing deterioration of the quality of service.
Next, more detailed examples of
First, a detailed explanation will be given of the routers (R1, R2, R3, and R4) and nodes (MN, CN1) shown in
<Mobile Node>
The mobile node supports the Mobile-IPv6 protocol. This mobile node is normally connected to the network 1 of the home link of the mobile node and communicates using the home address A. When moving to a network other than the home link (network 1), it generates a CoA (Care-of Address) for use in the network moved to. Further, it transmits a binding update to the home agent router 20 and the correspondent node CN1 by the Mobile-IPv6 protocol. Further, the mobile node is assumed to hold authentication information SA1 with the home agent router 20 and authentication information SA2 with the correspondent node CN1. “SA1” and “SA2” stand for “Security Association 1” and “Security Association 2”.
<Home Agent Router>
The home agent router is a router or server providing a home agent service under the Mobile-IPv6 protocol in the network 1 of the home link of the mobile node. In this example, the address of the home agent router 20 is made D. Further, the home agent router 20 is assumed to hold authentication information SA1 with the mobile node.
When the home agent router receives the binding update transmitted from the mobile node, the home agent router generates and holds the binding cache. When generating the binding cache, the home agent router returns a binding acknowledgment (BA) to the mobile node. During the validity of the binding cache, the home agent router intercepts packets transmitted addressed to the mobile node and Ip-in-IP encapsulates and transfers the packets toward the CoA (=address B) of the mobile node.
<Correspondent Node CN1>
The correspondent node CN1 is a node communicating with a mobile node and supporting the Mobile-IPv6 protocol. In this example, the address of the correspondent node CN1 is made E. Further, assume the correspondent node holds the authentication information SA2 with the mobile node.
When receiving a binding update transmitted from the mobile node, in the same way as the home agent router, the correspondent node generates and holds a binding cache. When transmitting a packet to the mobile node during the validity of the binding cache, the correspondent node uses an IPv6 extension header, that is, a routing option header, to directly transfer the packets to the CoA (=address B) of the mobile node. This is however operation in the normal case by the Mobile-IPv6. In the present invention, the router R2 receives the binding update and transfers packets to the CoA (=address B) instead of the correspondent node CN1.
<Routers R1, R3, and R4>
These are ordinary IPv6 routers.
<Router R2>
This is a mobile node adapted router having the above function of the present invention in addition to the functions of an ordinary IPv6 router. In this example, the router is assumed to hold authentication information SA2 with the mobile node in the same way as the correspondent node CN1.
Next, the operation of the system of
Step [1]: Assume that the mobile node has moved from the network 1 of the home link to the network 3.
Step [2]: The mobile node receives information of the network prefix (fixed code indicating the identity of each network) included in the “router advertisement” broadcast by the router R3 in the network 3, finds that it (mobile node) has moved outside of the network 1, and generates a CoA (here, made the address B).
Step [3]: The mobile node transmits a binding update to the home agent router 20 and notifies the CoA (=address B) as the current address.
Step [4]: The home agent router 20 stores the home address (=A) and CoA (=B) of the mobile node etc. as the binding cache based on the received binding update. Further, it returns a binding acknowledgment to the mobile node by a not shown route.
Step [5]: Here, assume that the correspondent node CN1 transmits a packet to the mobile node. The correspondent node CN1 still does not know that the mobile node is moving toward the network 3, so the packet is transmitted to the home address (=A) of the mobile node. The packet is transferred to the network 1 of the home address (=A) of the mobile node through the router R1→R2. At this time, the home agent router 20 intercepts the packet, IP-in-IP encapsulates it, and transfers it to the moving mobile node. The content of the packet at this time is shown in the figure.
In addition to the original packet (destination address=A, origination address=E) transmitted by the correspondent node CN1, another IP header (destination address=B, origination address=D) is added by the home agent router. This is an IP-in-IP encapsulated packet.
Step [6]: The mobile node returns a binding update to the correspondent node CN1 originating the original packet when receiving the above IP-in-IP encapsulated packet from the home agent router 20. The content of the packet at this time is shown in the figure.
The binding update signal becomes a packet of a format comprised of an IPv6 header (destination address=E, origination address=B) plus a binding update option (document [3]), home address option (document [3]), and authentication header (document [4]).
Each of the binding update option and the home address option is defined as one of the IPv6 extension headers (document [2]), that is, destination option headers (document [2]). The values of the option types are C6 (hexadecimal) for the binding update option and C9 (hexadecimal) for the home address option.
Up to step [6], the operation is that of an ordinary operation based on the Mobile-IPv6 protocol.
Step [7]: At step [6], the router (R2) 10 according to the present invention receives the binding update of
The mobile node adapted router R2 checks the content of the received binding update packet.
First, the router detects by the registering means 13 (
Next, since the destination address of the IPv6 header of
Further, the router uses the authentication information SA2 for the correspondent node CN1 to check the authentication header of
Further, when the check of the authentication header succeeds, the mobile node adapted router R2 generates a binding cache from the home address (=A) of the mobile node obtained from the home address option of
Step [8]: In the binding update option included in the packet of step [6], when an acknowledge bit (so-called “A-bit”) is set, the mobile node adapted router R2 returns a binding acknowledgment (BA) to the mobile node by the transfer means 12 (
The binding acknowledgment (BA), as shown in
The binding acknowledgment option is defined as a destination option header as one of the IPv6 extension headers. The value of the option type is 07 (hexadecimal).
The routing header, like the destination option header, is defined as an IPv6 extension header and determines the destination address of the IPv6 packet during transfer.
The above will be summarized with reference to
When the correspondent node is the correspondent node CN1 supporting the Mobile-IPv6 protocol, the current address of
At this time, the transfer means 12 of
Next, refer to the above
Step [9]: Here, assume that the correspondent node CN1 transmits a packet addressed to the mobile node. At this time, the mobile node adapted router R2 receives and holds the binding update from the mobile node to the correspondent node CN1 at step [7], so the correspondent node CN1 does not know that the mobile node is moving to the network 3. Therefore, the correspondent node CN1 transmits a packet addressed to the home address (=A) of the mobile node as normally.
Step [10]: When the mobile node adapted router R2 receives the packet transmitted at step [9], the transfer means 12 of the mobile node adapted router R2 (
(I) Transfer by using a routing header, that is, one IPv6 extension header.
(II) Transfer by IP-in-IP encapsulation.
Further, the following processing 1) and 2) may be performed depending on whether the packet transmitted by the correspondent node CN1 includes an authentication header or not.
1) Transfer Using Routing Header
To explain this case, refer to
In more detail,
Referring to
1-a) when a packet transmitted by the correspondent node CN1 does not include an authentication header such as in
The packet of
1-b) When a packet transmitted by the correspondent node CN1 includes an authentication header such as in
It should be noted here that the authentication header is not added as what is included in
The authentication data in the authentication header is normally calculated using just the content of the IP packet. Therefore, the authentication data calculated using the content of the packet of
2) Transfer by IP-in-IP Encapsulation
For the explanation of this case, refer to
In more detail,
Referring to
2-a) When a packet received by the correspondent node CN1 does not include an authentication header such as in the above-mentioned
The packet of
2-b) When a packet received by the correspondent node CN1 includes an authentication header such as in
The packet of
Here, the reason for making the origination address of the IPv6 header newly added by the mobile node adapted router R2 the address (=E) of the correspondent node CN1 originating the original packet [9] will be explained below.
According to the Mobile-IPv6 protocol, it is defined that when the mobile node receives an IP-in-IP encapsulated packet, the mobile node determines the compliance of the packet, and if compliant, a binding update is transmitted to the origin of the IP-in-IP encapsulated original packet. Normally, the home agent router intercepts a packet transmitted from the correspondent node CN1 not yet knowing the CoA of the mobile node to the home address of the mobile node (=A), IP-in-IP encapsulates the packet, and transfers this to the mobile node. The mobile node receiving the encapsulated packet transmits a binding update to the correspondent node. This operation is based on the above definition.
When transferring a packet from the mobile node adapted router R2 to the mobile node as in step [10] in
That is, one of the conditions for decision of compliance of the mobile node is the condition that “the origination address of the IPv6 header of the original packet and the origination address of the IP-in-IP encapsulated IPv6 header differ” (see document [3] 10.8. Sending Binding Updates to Correspondent Nodes). When using an IP-in-IP encapsulated packet when transmitting a packet from the mobile node adapted router R2 to the mobile node utilizing this in reverse, as shown in
Summarizing the above with reference to
Further, the transfer means 12 IP-in-IP encapsulates the packet by the IPv6 header including the current address (CoA) (
The first detailed example explained above (
First, an explanation will be given of the home agent router 20 and the mobile node adapted router R2 and nodes (mobile node and correspondent node CN2) shown in
<Mobile Node>
This is the same as the first detailed example (
<Home Agent Router 20>
This is a home agent router having a function based on the present invention in addition to the ordinary Mobile-IPv6 functions shown in the first detailed example. In this example, the home agent router is assumed to have authentication information SA3 with the mobile node adapted router R2.
<Correspondent Node CN2>
The correspondent node CN2 is a correspondent node communicating with the mobile node, but does not support the Mobile-IPv6 protocol. In this example, the address of the correspondent node CN2 is made F. When transmitting a packet to the mobile node, the packet is transferred normally using the destination address as the home address of the mobile node (=A).
<Routers R1, R3, and R4>
These are ordinary IPv6 routers.
<Router R2>
This is a router having the above function based on the present invention in addition to the functions of a normal IPv6 router. In this example, the address of the mobile node adapted router R2 is made G. Further, assume that the mobile node adapted router R2 does not have authentication information SA2 with the correspondent node CN1 shown in the first detailed example, but has authentication information SA3 with the home agent router 20.
Next, the operation of the system of
Steps [1] to [4]: These steps are the same as steps [1] to [4] of the first detailed example (
Step [5]: The correspondent node CN2 transmits a packet to the mobile node. Here, the correspondent node CN2 does not support Mobile-IPv6, so the packet is always transmitted to the home address of the mobile node (=A).
The operation up to step [5] is a normal operation based on the IPv6 and Mobile-IPv6 protocol.
Step [6]: When the mobile node adapted router R2 receives the packet transmitted at step [5], the registering means 13 of the mobile node adapted router R2 (
When not storing the binding cache for the destination address (=A), the mobile node adapted router R2 IP-in-IP encapsulates the packet and transfers it to the home agent router. The content of the packet at this time is shown in the figure.
The packet [6] becomes the packet transmitted by the correspondent node CN2 plus another new IPv6 packet header (destination address=A, address of originating mobile node adapted router R2=G).
Step [7]: The packet transferred from the mobile node adapted router R2 at step [6] is received by the home agent router 20. In this home agent router, the registering means 23 (
Next, it checks the original packet contained inside of the outside IPv6 packet header shown in
Next, the home agent router 20 checks the existence of a binding cache for the mobile node and its validity by the registering means 23. When the check reveals that there is a binding cache for the mobile node and it is valid, the home agent router reencapsulates the original packet addressed to the CoA of the mobile node (=address B) and transfers it. The content of the packet at that time is shown in the figure.
The home agent router adds another IPv6 header (destination address=B, address of originating home agent router=D) to the original packet [5] (destination address=A, origination address=F) transmitted by the correspondent node CN2.
Step [8]: Further, the home agent router 20 checks the origination address (G) contained in the outside IPv6 packet header of the packet shown in
The notification is a procedure independent of the Mobile-IPv6 protocol, so any means may be used to notify the CoA to the mobile node adapted router R2. In this example, it is assumed that it is notified using the binding update of the Mobile-IPv6. The content of the packet at this time is shown in the figure.
As shown in the figure, the notification packet becomes an IPv6 header (destination address=G, origination address=D) plus a binding update option, home address option, authentication header, and COA option. The binding update option, the home address option, and the authentication header are similar to those shown at step [6] of the first detailed example (
The authentication data included in the authentication header is calculated by using the authentication information SA3 between the home agent router 20 and the mobile node adapted router R2 and the content of the packet.
Further, the CoA option is not defined in the Mobile-IPv6, so can be defined as a new option. The content of the new option is shown in the figure.
In this figure, the CoA option, like the binding update option, is processed by the registering means 13 (
In the example of the format of
Step [9]: Returning to
Next, it judges that (i) the destination address of the IPv6 header (
Next, it checks the authentication header (
Here, since the CoA option (
Therefore, by forming a packet as shown in
By the above operation, a binding cache is generated for the mobile node at the mobile node adapted router R2. Thereafter packets transmitted from the correspondent node CN2 to the mobile node are transferred by the route of CN2→R1→R2→R3→MN without going through the home agent router in the same way as [10] of the first detailed example (
In the second detailed example (
If assuming that the correspondent node CN2 holds authentication information for the mobile node, an authentication header is included in the packet transmitted from the correspondent node CN2 to the mobile node. When an authentication header is included in this way, the packet is transferred by the method of 1-b) or 2-b) shown in step [10] in the first detailed example.
Further, in the same way as the above step [6] in the first detailed example, the binding update is transmitted from the mobile node to the correspondent node CN2. In this case, in the same way as steps [7] to [10] in the first detailed example, the mobile node adapted router R2 receives the binding update addressed to the correspondent node CN2 and transfers the packet directly from the mobile node adapted router R2 to the CoA of the mobile node.
The above point will be summarized below with reference to
When the other router (R2) cooperating with the home agent router is a mobile node adapted router able to communicate with the mobile node supporting the Mobile-IPv6 protocol, the address update notifying means 22 (
The authentication header (
Finally, a supplementary explanation will be given of the detailed examples of the mobile node adapted router (R2) 10 and home agent router 20 according to the present invention.
The routers 10 and 20 shown in
First, for convenience in explanation, the first detailed example of the above system (
In the figure, the mobile node MN1 (home address=A1) corresponds to the mobile node of
In
Further, the mobile node MN2 and the correspondent node do not have security information between them, so the mobile node MN2 transmits only the binding update (BU) 21 to the home agent router while moving.
Further, the home agent router and mobile node adapted router R2 have the security information SA3 between them. The home agent router transmits the CoA of the mobile node MN2, that is, the binding update (BU) 3, to the mobile node adapted router R2.
Note that the authentication information SA12 of the correspondent node is provided instead by the mobile node adapted router R2, so does not have to be provided at the correspondent node.
As shown in the figure, the router (R2) 10 can also be expressed by functional blocks substantially the same as the router (HA) 20. The content of the table, however, differs by the router 10 and router 20 (explained later). Further, the upstream side processing and downstream side processing of the packets are the same.
The mobile table 31 stores the information necessary for storing the CoA of the mobile node and transferring a packet by an optimized route. Note that examples of the content of the table are shown in
The routing table 32 is the same as a routing table of a normal router. It is a table storing information referred to when deciding the routing of a packet. Note that examples of the content of the table are shown in
The protocol processing means 33, as illustrated, includes a Mobile-IPv6 processing unit 331, a routing processing unit 332, a routing protocol processing unit 333 and another protocol processing unit 334. It interprets the content of a packet in accordance with protocols (Mobile IPv6, ICMP, etc.) and processes the message based on this.
The packet processing unit 34 determines the type of the packet and hands over the protocol processing to the protocol processing means 33. Further, the processing unit corrects and generates a packet and inputs it to the transmission unit based on an instruction from the protocol processing means 33.
The reception unit 35 receives a signal from a transmission path forming the network, assembles the frames, and checks the normality of the data.
The transmission unit 36 places the transmission packet from the packet processing unit 34 on a transmission frame and sends it over the above transmission path.
The mobile table 31 of
Note that the CoA of the mobile node MN is erased when the validity runs out. Further, in practice, information for a plurality of mobile nodes may be stored for a single correspondent node.
Looking at the mobile table-mobile node information, this information is notified from the home agent router and cached. When the validity runs out, all entries of the mobile node home address, CoA, and validity are erased.
The mobile table 31 of
The mobile table mobile node information is erased when the validity for the CoA of the mobile node runs out.
The routing table 32 of
The routing table 32 of
Further explaining
Further explaining
Further, along the route 42 of
Further explaining
Further explaining
Further, along the route 44, the home agent router transfers the packet P2 of
Further, along the route 45, the home agent router receives the binding update from the mobile node MN1 and the mobile node MN2 and returns the binding acknowledgment. This is a normal registration operation.
Above, a detailed explanation was given of the routers 10 and 20. Assume however that, at the end of 2-b) in it, “the problem of continuous transmission of the binding update disappears if the condition for decision of compliance is no longer satisfied at the mobile node”. For just the first packet, however, to start the registering means 13 (
The first packet from the correspondent node to the mobile node is sent to the home address of the mobile node in the form of the packet P5 or P6 of
The URLs of the documents mentioned in this specification are as follows:
Document [1] (mobile IP):
Summarizing the effect of the invention, as explained above in detail, the present invention can shorten the time required for updating the CoA accompanying movement of a mobile node and increases the speed of switching of the packet transfer route.
Further, it is possible to optimize the packet transfer route from a correspondent node not supporting a mobile-IPv6 to a mobile node without going through a home agent router.
Due to this, it becomes possible to prevent an increase in the packet transfer delay and packet loss causing a deterioration in the quality of service.
While the invention has been described with reference to specific embodiments chosen for purpose of illustration, it should be apparent that numerous modifications could be made thereto by those skilled in the art without departing from the basic concept and scope of the invention.
The present disclosure relates to subject matter contained in Japanese Patent Application No. 2000-377628, filed on Dec. 12, 2000, the disclosure of which is expressly incorporated herein by reference in its entirety.
Number | Date | Country | Kind |
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2000-377628 | Dec 2000 | JP | national |
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Number | Date | Country | |
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20020071417 A1 | Jun 2002 | US |