A packet transmission control apparatus has a packet accumulating unit for buffering a plurality of packets. The apparatus further includes a transmission unit for and for transmitting, to a destination node, a front packet included in the plurality of packets buffered in the packet accumulating unit and for transmitting the remaining packets included in the plurality of packets to the destination node after a lapse of a time period starting from a time point of transmission of the front packet. The time period is equal or greater than a sum of predetermined downstream front packet processing time periods, the sum corresponding to a number of nodes the front packet passes through before reaching the destination node.
In a packet communication system 1, 31 (51, 81) comprised of nodes and links, a destination node 3 (53) as a destination of a packet transmitted from correspondent node 2 (52) is provided with an advertisement receiving device 3e (53e) for receiving an advertisement of path information about a path from the correspondent node 2 (52) to the destination node 3 (53); a Path MTU discovery execution determining device 3f (53g) for determining whether a discovery of a Path MTU of the path from correspondent node 2 (52) to destination node 3 (53) should be executed, based on the path information; a Path MTU setting device 3g (53f) for setting the Path MTU on the basis of the path information; and a Path MTU announcing device 3h (53h) for announcing the Path MTU set by the Path MTU setting device 3g (53f).
In a state I, a link layer of a mobile host is connected to an access router and a default router is set to the access router such that data packets (P1) and (P2) reach the access router and are routed to a correspondent host. In states II and III, data packets (P3) to (P8) are not transmitted but are buffered. When the mobile host switches the default router from the access router to an access router upon reception of a router advertisement from the access router, processing moves to a state IV and the buffered data packets (P3) to (P8) are transmitted. Since the link layer of the mobile host is connected to the access router and the default router is set to the access router, the data packets (P3) to (P8) reach the access router and are routed to the correspondent host.
In a state I, a link layer of a mobile host is connected to an access router and a default router is set to the access router such that data packets (P1) and (P2) reach the access router and are routed to a correspondent host. In states II and III, data packets (P3) to (P8) are not transmitted but are buffered. When the mobile host switches the default router from the access router to an access router upon reception of a router advertisement from the access router, processing moves to a state IV and the buffered data packets (P3) to (P8) are transmitted. Since the link layer of the mobile host is connected to the access router and the default router is set to the access router, the data packets (P3) to (P8) reach the access router and are routed to the correspondent host.
When a mobile node MN moves from an access router AR3 to another access router AR4, it sends a multi-binding on request to a mobility agent MA1 and then moves ({circle around (1)}). Receiving the multi-binding on request, the mobility agent MA1 voluntarily configures prospective CoA's (probable CoA's) The probable CoA's are added as forwarding addresses while an M bit is set on in an register of the mobile node MN on a binding cache ({circle around (2)}). When the mobility agent MA1 receives a capsuled packet addressed to the mobile node MN thereafter, it tunnel-forwards the packet to CoA3, probable CoA2, and probable CoA4 according to the binding cache ({circle around (3)}).