signed before and after the migration as well as the
`address assigned before the last migration. Thereby,
`the hosts attached to the network 1 can communicat(cid:173)
`ed with the mobile host directly.
`
`(migration from network 2 to network 3)
`
`When migrating from the network 2 to the net(cid:173)
`work 3, the mobile host 11 obtains m" at the address
`assigned after the migration. Then the mobile host 11
`notifies the gw 2 and a gw 3, both of which are attach-
`ed to the network 2, that the mobile host 11 has mi(cid:173)
`grated to the network 3 by transmitting thereto a
`packet comprising the migration post message, refer-
`red to as a packet 62 in FIG. 7. FIG. 12 (b) shows a
`format of the packet 62, which is transmitted to the gw
`2. The broadcast address of the network 2 can be em(cid:173)
`ployed as the destination address of the packet 62.
`When the packet 62 is transmitted to the broadcast
`address of the network 2, every host attached to the
`network 2, which includes the gw 2 and the gw 3,
`holds the correspondence of the addresses each as(cid:173)
`signed before and after the migration.
`The gw 2 employs its devices in FIG. 3 to process
`the packet 62. That is. receiving the packet 62. the gw
`2 sends it to the migration post information unit 36 via
`the communication control unit 4 and the reception
`packet unit 35,
`then refers to the data hold unit 1
`where m~m' and 0 are still held at the address cor-
`respondence and at the address assigned before the
`last migration respectively. The migration post infor(cid:173)
`mation post unit 36 obtains from the packet 62 m'- ,
`m" as the newly assigned ~orrespondencebetween
`the addresses each of which assigned before and af-
`ter the current migration, the migration from the net-
`work 2 to the network 3. Then. it detects whether or
`not the address m' coincides with the addrel)s held In
`the data hold unit 1 as the address assigned after the
`last migration. Since the unit 36 detects the coinci-
`dence, it replaces the address m' in the unit 1 with the
`, address m" as well as replaces the correspondence
`mom' with the correspondence m-m".
`Also the migration post Information unit 36 sends
`to the data hold unit 1 the address m assigned before
`the last migration together with the address corre-
`spondence m'-m" obtained from the current migra-
`tion. Now the data hold unit 1 in the gw 2 holds the
`address m at the address assigned before the last mi(cid:173)
`gration and the address correspondence m'-m" at
`the correspondence of the addresses each of which
`assigned before and after the migration as well as the
`address 0 at the address assigned before the last mi(cid:173)
`gration as well as the address correspondence m-
`m' at the correspondence of the addresses each of
`which assigned before and after the migration. After
`updating as well as adding the addresses in the data
`hold unit 1. the migration post information unit 36
`sends to the address conversions post transmission
`
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`unit 38 m'-m" as the newly obtained correspondence
`of the addresses before and after the current migra(cid:173)
`tion.
`
`The address conversion post transmission unit
`38 detects the network satisfying the following con(cid:173)
`ditions with referring to the data hold unit 1 and then
`transmits the address conversion post message to
`the broadcast address of the detected network. That
`is. the address conversion post message is transmit(cid:173)
`ted to the network where the address assigned be(cid:173)
`fore the migration. which is held in the data hold unit
`1, is other than 0 as well as the migration communi(cid:173)
`cation control device employed as the gateway is not
`attached. Although in the migration from the network
`2 to the network 3, the data hold unit 1 holds m at the
`address assigned before the last migration, the gw 2
`is attached to the network 1; therefore. the unit 38
`does not transmit the address conversion post to the
`network 1.
`The packet 62 is also received by gw 3. When re(cid:173)
`ceiving the packet 62, the gw 3 employs its own de(cid:173)
`vices in FIG. 3 to process the packet 62, which is sub(cid:173)
`stantially same as does the gw 2 except the following.
`That
`is.
`the address conversion post transmission
`unit 38 of the gw 3 detects t: lat tne gw 3 is not attach(cid:173)
`ed to the network 1. Also it is detected that the mobile
`host 11, attached to the network 1, has the address
`m as the address assigned before the last migration.
`Therefore, the unit 38 of the gw 3 transmits to the
`broadcast address of the network 1 a packet compris(cid:173)
`ing the address conversion post message, which is
`referred to as a packet 63. FIG. 12 (c) shows the
`packet 63.
`The packet 63 is received by the gw 2, the gw 1,
`both of which are attached to the network 1. Although
`it is also received by the stationary host 11, this will
`not be described here. Obtaining the current address
`correspondence m'-m" from the packet 63. where
`m' coincides with the address which has been held in
`the hold unit 1 at the address obtained after the mi(cid:173)
`gration, the gw 1 changes the mom' in the data hold
`unit 1 into the m-m" by replacing m' with m" as the
`address assigned after migration.
`On the other hand, the data hold unit 1 of the gw
`2 had gained from the packet 62 the above informa(cid:173)
`tion before receiving the packet 63. Therefore the
`content of the unit 1 of the gw 2 does not change
`across reception of the packet 63. This is because the
`gws of the present invention locate on a gateway,
`which connects a couple of networks. Due to its loca(cid:173)
`tion, each gw receives packets from two networks.
`However, actually the packet 62 is destined for the
`network 2 and the packet 63 is destined for the net(cid:173)
`work 1. Therefore, even though the gw 2, which are
`attached to both the network 1 and the network 2, re(cid:173)
`ceives both the packet 62 and 63 by the gw 2, this will
`not bause 'any problem in the communication be(cid:173)
`tween the stationary host 12 and the mobile host 11.
`
`SONY EXHIBIT 1027- Page 277
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`FH_000277
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`29
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`EP 0 556 012 A2
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`30
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`FIG. 13 (b) shows the content of the data hold uni.t
`1 in each of the gws.
`
`(migration from network 3 to network 4)
`
`When migrating from the network 3 to the net(cid:173)
`work 4, the mobile host 11 obtains m'" as the address
`assigned after the migr.ation. Then the mobile host 11
`sends to the gw 3 and a gw 4, both of which are at-
`tached to the network 3, a packet comprising the mi-
`gration post message. The packet received by the gw
`3 is referred to as a packet 64. The broadcast address
`of the network 3 can be employed as the destination
`address of the packet 64. When the packet 64 is des-
`tined for the broadcast address of the network 3, ev-
`ery host attached to the network 2, which includes
`the gw 3 and the gw 4, obtains from the packet the
`correspondence of the addresses each of which as(cid:173)
`signed before and after the migration from the net-
`work 3 to the network 4.
`The gw 3 employs its devices in FIG. 3 to process
`the pa,,;,el 34. 7; lat is, receiving the packet 64, the gw
`3 converts the content of the data hold unit 1 by re(cid:173)
`placing the address correspondence m-m" with m-
`m"', newly holding m"-m'" obtained from the packet 64
`as well as the address m' assigned before the last mi(cid:173)
`gration. Then, the address conversion post transmis-
`sion unit 38 of the gw 3 transmits the address conver-
`sion post message to the network satisfying the fol-
`lowing condition. That is, the address conversion post
`message is transmitted to the network where the ad(cid:173)
`dress assigned before the migration, which is held in .
`the data hold unit 1, is other than 0 as well as the gw
`3 it self is not attached. The packet including the ad-
`dress conversion post message is referred to a pack-
`et 65, and the packet is transmitted to the broadcast
`address of the network 1. FIG. 7 (c) shows the packet
`65.
`
`The packet 64 is also received by gw 4. When re-
`ceiving the packet 64, the gw 4 renews the content
`of the data hold unit 1 by replacing m'-m" with m'-m'"
`as well as newly holding the address m' as the ad(cid:173)
`dress assigned before the last migration. Further, the
`address conversion post transmission unit 38 of the
`gw 4 detects that the gw 4 is not attached to the net-
`work 2 which has the address other than 0 at the ad(cid:173)
`dress assigned before the last migration; therefore,
`the unit 38 of the gw 4 transmits a packet comprising
`the address conversion post message, which is refer-
`red to as a packet 66, to the broadcast address of the
`network 2. FIG. 7 (c) shows the packet 66.
`Receiving the packet 65,65, the gw 2 and the gw
`1 renew the content of its data hold unit 1, which is
`substantially the same as the above.
`The gw 3 and the gw 2 receives the same infor-
`mation twice since the former receives the packet 64
`and 65 while the latter receives the packet 65 and 66.
`This is because gws of the present invention locate on
`
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`a gateway and receives packets from a couple of net(cid:173)
`works, which is described the above.
`FIG. 13 (c) shows the contentofthe data hold unit
`1 in each of the gws. Thus, according to the gws of
`the present invention, the packet transmitted to any
`of the addresses m, m', m" is transferred by the gws
`to the updated address of the mobile host, the gws
`also notify the stationary host of the updated ad(cid:173)
`dress.
`Fo"r example, when the stationary host is not no(cid:173)
`tified of the updated address of the mobile host and
`transmits a packet to the address m', the packet is re(cid:173)
`ceived by the gw 2 and the gw 3, both of which are
`attached to the network 2. Then, the gw 2 and the gw
`3 transfers the packet to the updated address of the
`mobile host as well as notifies the stationary host of
`the updated address. Thereby,
`the stationary host
`obtains the updated address of the mobile host, so
`that it will be able to communicate with the mobile
`host directly. The packet destined for the address
`m'
`is received by both the gw 2 and the gw 3, since
`they are attached to the network 2. Thus. the mobile
`host receives the same packet twice, once from the
`gw 2 and the other time from the gw 3, and the sta(cid:173)
`tionary host receives the same message twice; how(cid:173)
`ever, the repeated packetorthe message can be sim(cid:173)
`ply ignored, so that this will not cause any problem in
`the communication between the stationary host and
`the mobile host. The repeated packet orthe message
`is observed when the two gws are attached to each
`network in FIG. 7; whereas it is not observed when
`only one migration communication control device is
`attached to each network, which will be described lat(cid:173)
`er at the operation in FIG. 9.
`
`(operation example in FIG. 8)
`
`In FIG. 6, FIG. 7, the stationary host transmits the
`data packet to the outdated address after'mobile host
`notifies the gws that it has migrated to another net(cid:173)
`work. Then the gws transmit the address conversion
`post message to the stationary host. However, in FIG.
`8 the gws convert the destination address of data the
`packet from the outdated address into the updated
`address assigned after t he migration instead of trans(cid:173)
`mitting the address conversion post message.
`A packet 71, 72 in FIG. 8 are substantially same
`as the packet 51,52 in FIG. 6. The operation conduct(cid:173)
`ed before the packet 72 is transmitted by the station(cid:173)
`ary host 12 and is received by the gateway 13 is sub(cid:173)
`stantially same as the first operation in FIG. 6. The op(cid:173)
`eration which follows reception of the packet 72 is de(cid:173)
`scribed hereunder with referring to FIG. 3.
`The gate way 13 employs its units in FIG. 3 to
`process the packet 72. The communication control
`unit 4 receives the packet 72 and gives it to the recep(cid:173)
`tion packet unit 35 in the migration address unit 3. De(cid:173)
`tecting that the packet 72 is a general packet. the re-
`
`SONY EXHIBIT 1027- Page 278
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`FH_000278
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`

`
`ception pac".et unit 35 sends it to the address compar(cid:173)
`ison unit 37. The address comparison unit 37 detects
`whether or not the destination address of the packet
`72 coincides with the address in the data hold unit 1
`at the address assigned before the migration.
`When no coincides Is found. the address compar(cid:173)
`ison unit 37 gives the packet 72 to the application unit
`2. On the other hand, a coincidence is found, the ad(cid:173)
`dress assigned after
`the migration. which corre(cid:173)
`sponds with the address identical to the destination
`address of the packet 72. is obtained from the data
`hold unit 1, and is sent to the marked packet conver(cid:173)
`sion unit 39 together with the packet 72. The marked
`packet conversion unit 39 generates a packet
`72' where the destination addre~s of the packet 72 is
`replaced with the address assigned after the migra(cid:173)
`tion. which is sent by the address comparison unit 37,
`the destination address of the packet 72 is added as
`additional address, and a mark is set to indicate that
`the destination address has converted. Then the
`packet 72' is sent to the communication control unit4.
`FIG. 12 (e) shows a format of the packet 72', where
`identical numerals denotes the same units in FIG. 11.
`The packet 72'
`is sent to the mobile host 11 without
`fail since its destination address is the updated ad(cid:173)
`dress thereof.
`
`(operation example in FIG. 9)
`
`In FIG. 9, the mobile host migrates across net(cid:173)
`work 1, 2, 3, and 4. In FIG. 7 the gw 1-gw 4 are em(cid:173)
`ployed as the migration communication control devic(cid:173)
`es; whereas in FIG. 9 the gw 1-gw 4 are employed
`simply as gateways to connect networks, and also an(cid:173)
`other migration communication control device is at(cid:173)
`tached to each network. The operation of the migra(cid:173)
`tion communication control device, which is connect(cid:173)
`ed to the network alone. at processing the migration
`post message or the address conversion post mes(cid:173)
`sage is substantially same as one of the gw 1-gw 4 in
`FIG. 7. The flow of the migration post message and
`the address migration post message are mainly de(cid:173)
`scribed hereunder.
`
`(migration from network 1 to network 2)
`
`When migrating from the netw~rk 1 to the net(cid:173)
`work 2, the mobile host 11 sends a packetcompril!ling
`the migration post message to the migration commu(cid:173)
`nication control device, which is attached to the net(cid:173)
`work 1. In FIG. 9 (a) a migration post packet 81 is
`transmitted to a migration communication control de(cid:173)
`vice 51, which is attached to the network 1. The des(cid:173)
`tination address of the packet 81 can be the broad(cid:173)
`cast address of the network 1.
`The device 51 processes the packet 81 byem(cid:173)
`ploying its devices in FIG. 3. Receiving the packet 81,
`the device 51 stores into the data hold unit 1 the cor-
`
`respondence of the addre::.ses each assigned before
`arid after the migration as well as the address as(cid:173)
`signed before the last migration. The migration post
`information unit 36 transmits the packet 81 to the ad-
`dress conversion post transmission unit 38: however,
`since the unit 38 detects that the address assigned
`before the last migration ;s 0, it does not transmit the
`address conversion post message to any network.
`The content of the data hold unit 1 in the 51-54 are
`shown in FIG. 14 (a).
`
`(migration from network 2 to network 3)
`
`When migrating from the network 2 to the net-
`work 3. the mobile host 11 notifies the 52, which is
`attached to the network 2, that it,has migrated to the
`network 3 by transmitting thereto the packet compris(cid:173)
`ing the migration post message, which is referred to
`as a packet 82 in FIG. 9 (b).
`The 52 employs its devices in FIG. 3 to process
`the packet 82. That is, it converts the content of the
`data hold unit 1 by renewing and adding new informa(cid:173)
`tion. and finally holds in the unit 1 the address m'(cid:173)
`m" at the correspondence of the addresses each of
`which assigned before and after the migration as well
`as the address m assigned before the fast migration.
`Then, the migration post information unit 36 gives the
`newly obtained correspondence m'·m" to the ad(cid:173)
`dress conversion post transmission unit 38.
`The address conversion post transmission unit
`38 detects whether or not the address assigned be(cid:173)
`fore the last migration. which is held in the data hold
`unit 1, is O. If the address is not O. the unit 38 transmits
`the address conversion post message to the broad-
`cast address of the network which includes the de(cid:173)
`tected address. In FIG. 9 (b) the address m is held at
`the address assigned before the last migration, so
`that the unit 38 transmits the packet 83 to the broad(cid:173)
`cast address of the network 1.
`the migration
`When receiving the packet 83,
`communication control device 51. which is attached
`to the network 1, renews the content of the data hold
`unit 1 by newly holding the address correspondence
`m-m" as well as the address 0 at the address as-
`signed before the last migration. Detecting 0 at the
`address assigned before the last migration, the ad(cid:173)
`dress conversion post transmission unit 38 does not
`transmit the address conversion post to any network.
`The content of the data hold unit 1 in the 51-54 are
`shown in FIG. 14 (b).
`.
`
`(migration from network 3 to network 4)
`
`When migrating from the network 3 to the net-
`work 4, the mobile host 11 notifies the communica(cid:173)
`tion migration control device 53, which is attached to
`the tletwork 3, that it has migrated to the network 4
`by transmitting thereto a packet comprising the mi-
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`SONY EXHIBIT 1027- Page 279
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`FH_000279
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`33
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`EP 0556012 A2
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`34
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`gration post message, referred to as a packet 84 ie
`FIG. 9 (c).
`The migration communication control device 53
`employs its devices in FIG. 3 to process the packet
`84. That is. it newly holds into the data hold unit 1 the
`address correspondence m"-m'" as well as the ad(cid:173)
`dress m' assigned before the last migration. Then,
`the address conversiofl post transmission unit 38 in
`the 53 transmits a packet comprising the address
`conversion post message, referred to a packet 85 in
`FIG. 9 (c), to the broadcast address of the network 2
`since the address m' is held at the address assigned
`before the last migration in the data host unit 1.
`When receiving the packet 85,
`the migration
`communication cOQtrol device 52 employs its devices
`in FIG. 3 to process it. That is, it newly holds into the
`data hold unit 1 the address correspondence m'(cid:173)
`m" as well as the address m assigned before the last
`migration. Then, the address conversion post trans(cid:173)
`mission unit 38 in the 52 transmits a packet compris(cid:173)
`ing the address conversion pOiitmessage, referred to
`a packet 86 in FIG. 9 (c), to the broadcast address of
`the network 2 since the address m is held at the ad(cid:173)
`dress assigned before the last migration in the data
`hold unit 1.
`the migration
`When receiving the packet 86,
`communication control device 51 employs its devices
`in FIG. 3 to process it. That is, it newly holds into the
`data hold unit 1 the address correspondence m-m'"
`as well as the address 0 at the address assigned be(cid:173)
`fore the last migration. The address conversion post
`transmission unit 38 in the 51 does transmit the ad(cid:173)
`dress conversion post since 0 is detected at the ad(cid:173)
`dress assigned before the last migration. The content
`of t he data hold unit 1 in each of the 51-54 are shown
`in FIG. 14 (c). Thus, according to the migration com(cid:173)
`munication control device 51-54 of the present inven(cid:173)
`tion, the 51-54 are notified of the updated address of
`the mobile host at every migration, so that the packet
`transmitted to any of the addresses m, m', m" is trans(cid:173)
`ferred thereby to the updated address of the mobile
`host. The 51-54 also notify the stationary host of the
`updated address of the mobile host.
`The operation in FIG. 9 differs from the operation
`in FIG. 7 in that each network has just one communi(cid:173)
`cation migration control device (one of the 51-54), so
`that the migration post and the address conversion
`transmitted .to 51-54 are not duplicated.
`In the format shown in FIG. 11 and 12, the mark
`96 or the message type 93 indicates kind of packet.
`That is, mark 96 indicates whether or not the packet
`is marked while the message type 93 indicates
`whether it is the packet comprising the migration post
`message, the packet comprising the address conver(cid:173)
`sion post message, and the general packet. Further,
`a protocol
`type can also be employed to indicate
`which migration communication control device is em(cid:173)
`ployed. For example, when TCPIIP is employed, the
`
`the IP header thereof distin(cid:173)
`protocol number at
`guishes t he packet employed in t he embodiment from
`other packets. That is, when the protocol number in
`the packet is identical with the one, which has been
`assigned to the protocol number field, the packet is
`the one employed in the embodiment.
`In the first embodiment of the present invention,
`a nonvolatile storage can be employed as the data
`hold unit 1 of the mobile host. If so, the communica-
`tion ca'n be resumed even after the host or the gate(cid:173)
`way is turned off as well as after the system is reset.
`Also even when the stationary host employs the
`nonvolatile storage as the data hold unit 1, it can re(cid:173)
`sume the communication, which has interrupted by
`the switch off or the system reset, rather fast since it
`obtains from another host the updated address of the
`mobile host instead of receiving from the gateway the
`address conversion post message which shows the
`updated address.
`For example, it is supposed in FIG. 7 that the mo-
`bile host 11 migrates from the network 1 to the net(cid:173)
`work 4. The data hold unit 1 of the migration commu(cid:173)
`nication device holds the address correspondence
`m-m'" since it has communicated with the mobile
`host, which is attached to the network 4, at least
`once. According to the migration communication con(cid:173)
`trol device in the embodiment described the above,
`the packet is transferred from the outdated address
`to the updated address of the mobile host and the sta-
`tionary host is notified of the updated address; there(cid:173)
`fore, even when the address information in the data
`hold unit is lost e>y switch off thereof, the stationary
`host will obtain the updated address. Restart of the
`communication can also be implemented by employ-
`ing a specific host such as a server. That is, the ser(cid:173)
`ver may be constructed to obtain the updated ad(cid:173)
`dress of the mobile host at every migration. and give
`it to the stationary host whenever requested. In this
`case a packet comprising the address inquiry should
`be generated beforehand.
`Also in the fifth operation in FIG. 6, the mobile
`host 11 employs the application unit 2 and sends to
`the marked packet conversion unit 21 the address as(cid:173)
`signed before the migration when transmitting the
`non-response address to the stationary host after it
`has migrated to another network. Instead of sending
`'the non-response address, the application unit 2 can
`transmit a connection identifier to the marked packet
`conversion unit 21. In this case the data hold unit of
`the migration communication control device, em(cid:173)
`ployed as the mobile host, holds a correspondence
`between the connection identifier and the address
`that had been assigned when the connection was es(cid:173)
`tablished instead of holding the correspondence be-
`tween t he correspondence of the addresses each as(cid:173)
`signed before and after the migration. Then, the unit
`21 obtains the source address of the packet by de(cid:173)
`tecting the address which corresponds to the identi-
`
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`SONY EXHIBIT 1027- Page 280
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`FH_000280
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`
`fier, which is held in the data hold unit 1.
`As is described the above, the mobile host can
`employ,the broadcast address of the network when
`transmitting the migration post to the migration com-
`munication control devices. When the broadcast ad-
`dress is employed, every host attached to the net(cid:173)
`work, to which the migration communication control
`device is also attached, obtains the updated address
`of the mobile host. This implements a direct commu-
`nication between the mobile host and the stationary
`host, which improves efficiency of the communica-
`tion.
`
`The address assigned before the last migration,
`which is held in the hold unit 1, can be replaced with
`the broadcast address assigned to the network to
`which the mobile host is attached before the last mi(cid:173)
`gration.
`If the broadcast address is employed,
`the
`gateway employed as the migration communication
`control device (gws) or the migration communication
`control device (Ss) needs to include the broadcast ad-
`dress in the address conversion post message. In this
`case both devices can obtain the broadcast address
`from the data hold unit;
`therefore,
`the operation
`thereof at requesting the broadcast address will be
`eliminated.
`When storage capacity of the dat? hold unit 1 is
`limited, the data hold unit 1 holds only the useful data
`by disposing the unuseful data, which is least recently
`retrieved therefrom by the address comparison unit.
`
`[Embodiment 2)
`
`In FIG. 15 network A, B, and C are connected in
`a line via gateways 143 arid 143', the gateway 143
`placing between the network Aand B while the gate-
`way 143' placing between the network Band C.
`A home migration communication control device
`101 including a migration address unit 144 is attached
`to the network A; a visitor migration communication
`control device 109 including a migration address unit
`145 is attached to the network B; and a visitor migra-
`tion communication control device 109'
`including a
`migration address unit 145' is attached to the network
`C. A mobile host 146 including a migration address
`unit 115 is attached to the network A as its home net-
`work, and a stationary host 151 including a migration
`address unit 125 is also attached to the network A.
`The mobile host 146 migrates across the netw9rk
`A, B, and C. It has a home address a assigned when
`it is attached to the network A, as well as other ad-
`dresses- assigned depending on where it migrates,
`such as a temporary address J3 on the network Band
`a temporary address y on the network C.
`Also each of the home migration communication
`control device 101, the visitor migration communica-
`tion control device 109,109' which are identical in its
`construction and the stationary host 151 has an ad(cid:173)
`dress Ha, Va, Va', and Sa respectively assigned on
`
`the network.
`Detailed function of the above devices 101, 109,
`109', 146, and 151 is described hereunder, in which
`like components are labeled with like reference nu(cid:173)
`merals.
`
`[home migration communication control device 101]
`
`When the mobile host 146 migrates from the
`home network to another network, it is assigned the
`temporary address. However if the stationary host
`151 is not notified of that migration, it transmits an
`original data packet (hereinafter referred to as a non(cid:173)
`capsulated data packet) to the home address a of the
`mobile host 146. When the noncapsulated data pack(cid:173)
`et is destined for the outdated address of the home
`mobile host 146, the home migration communication
`control device 101 transfers that noncapsulated data
`packet from there to the updated address, that is the
`temporary address J3 oryofthe mobile host. Then, the
`device 101 posts to the stationary host 151 the tem(cid:173)
`porary address J} ory here, so that the stationary host
`151 will be able to communicate directly with the mo(cid:173)
`bile host. The device 101 also posts the same infor(cid:173)
`mation to the visitor migration communication control
`device 109, 109', so thatthe devices 109, 109' will im(cid:173)
`plement the same function with the home migration
`communication control device 101.
`As shown in FIG. 16 the home migration commu(cid:173)
`nication control device 101 consists of the migration
`address unit 144 and a communication control unit
`108. The migration address unit 144 further compris(cid:173)
`es a home mobile host (MH) list hold unit 102, a pack(cid:173)
`et transfer unit 103, a mobile host (MH) transfer unit
`104, an address inquiry unit 105, a packet monitoring
`unit 106, an address post unit 107.
`Next the function of each component integrating
`the device 101 will be described. The communication
`control unit 108 mainly controls the communication of
`protocols located in lower Iflyer~ ::-:c:~di,llJ a ~h~:>ical
`layer, such as the protocol lower than IP.
`The address post unit 107 receives from the mo(cid:173)
`bile host 146 an data packet including an address post
`message. The address post message is generated
`when the mobile host 146 migrates to the network B
`or C, and posts the temporary address J3 or y of the
`mobile host to the device 101. The unit 107 sends the
`address post message to the mobile host transfer unit
`104 as well as sends a response '!lessage to the mo(cid:173)
`bile host 146. FIG. 28 (3) is an example of t he address
`post message, which includes the home address u as
`well as the temporary address J3 or y of the mobile
`host 146, a value of an autonomous flag F, and a
`broadcast address Bba, Cba on the network B, C.
`The autonomous flag F will be described later. FIG. 28
`(4) is an example of the response message.
`A mobile host transfer unit 104 stores the address
`post message into the home mobile host list hold unit
`
`5
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`10
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`15
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`20
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`25
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`30
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`35
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`40
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`45
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`50
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`55
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`19
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`SONY EXHIBIT 1027- Page 281
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`FH_000281
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`

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`37
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`EP 0 556 012 A2
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`38
`
`102. notifies the visitor migration communication con:
`trol device 109 or 109' of the migration of the mobile
`host 146 by sending t hereto a mobile host transfer
`message, and receives the data packet including the
`response. Further. according to a direction given by
`the pac.."et iransrer Ulllt 103, the unit 104 transmits
`the mobile host transfer message both to the station(cid:173)
`ary host 151 and the device 109 or 109', The unit 103
`gives the direction whe'n the value oft he autonomous
`flag F is 1.
`FIG. 32 (3) and FIG. 36 (5) are examples of the
`mobile host transfer message including the home ad(cid:173)
`dress u, the temporary address Il or y, and the auton(cid:173)
`omous flag F. Since the mobile host transfer message
`is sent to the stationary host 151 is sent only when the
`autonomous flag F is 1; therefore, it does not neces(cid:173)
`sarily include the value of the flag F. However, the
`identical message is sent both to the stationary host
`151 and the visitor migration communication control
`device 109, 109'
`in this embodiment to simplify the
`construction of the mobile host transfer unit 104. FIG
`32 (4) is an example of the response message.
`As shown in FIG. 17, the home mobile host list
`hold unit 102 holds the home address u, the tempor(cid:173)
`ary address Il, y, the value of the autonomous flag F,
`and the broadcast address Bba, Cba on the network
`B, C, all of which are obtained from the mobile host
`transfer unit 104.
`The packet monitoring unit 106 receives the
`packet destined for the home address U of the mobile
`host 146, then sends it to the packet transfer unit 103
`when the stationary host 151 transmits the packet to
`the home address u of the mobile host 146 after the
`mobile host 146 has migrated to another network.
`The packet transfer unit 103 has a payload includ(cid:173)
`ing the noncapsulated data packet and the packet
`transfer message informing the transfer of the non(cid:173)
`capsulated data packet, generates another data
`packet, and sends it to the temporary address Il, y of
`the mobile host 146. FIG. 32 (2) is an example of the
`packet transfer message. As is described the above,
`the packet transfer unit 103 directs the mobile host
`transfer unit 104 to transmit the mobile host transfer
`message to the stationary host 151 only when the au(cid:173)
`tonomous flag in the home mobile host list hold unit
`102 shows the value of 1. The operation conducted
`when the flag F is 1 will be described later.
`When the stationary host 151 has problems in
`communicating with the mobile host 146 such as re(cid:173)
`ceiving the unusual mobile host transfer message,
`the address inquiry unit 105 is employed to solve the
`problems. That is, receiving from the stationary host
`151 an address inquiry message, the address inquiry
`unit 105 transmits to the stationary host 151 a data
`packet which responds to the address inquiry by
`showing the address to be used in the communica(cid:173)
`tion. The address inquiry message includes a type
`field 132, a flag field 133, a sequence field 134, and
`
`a home address