Ip switching center, the interface circuit and atm switching center for use for the ip switching center, as well as an ip switching network system

摘要

PROBLEM TO BE SOLVED: To protect ALL frames and to prevent the loss of packets by referring to the PT field of ATM cells during transfer at present and waiting for the execution of changeover until the boundary of frames is recognized in switching a virtual transfer line. ;SOLUTION: A virtual transfer line change request G2 arrives after a cell C1 has been processed, however, as indicated by a change waiting period W1, the changeover of the virtual transfer line is waited for until the cell positioned at the boundary of the frames, that is the cell Cn for which the value of the PT field is 1, arrives. Thus, no packet is lost in communication from a node 1A to the node 1B and the communication 18 normally performed. Then, once judged that the setting change of a switch is required, a packet processing part 21 sends out the virtual transfer line change request to a switch part 24. A switch control part inside the switch part 24 receives it, converts it to an interface control instruction and transfers it.;COPYRIGHT: (C)1998,JPO