Packet-switched communications network with parallel virtual circuits for re-routing message packets

• US 4,884,263 A
• Filed: 03/17/1989
• Issued: 11/28/1989
• Est. Priority Date: 01/09/1986
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Suzuki, Hiroshi
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US07/325,010
• Time in Patent Office: 256 Days
• Field of Search: 370/16, 370/60, 370/84, 370/85, 340/827, 340/825.01
• US Class Current: 370/225
• CPC Class Codes: H04L 45/10 Routing in connection-oriented networks, e.g. X.25 or ATM
• CPC Class Codes: H04L 45/22 Alternate routing
• CPC Class Codes: H04L 45/247 using M:N active or standby paths
• CPC Class Codes: H04L 45/26 Route discovery packet

Abstract

In a packet-switched communications network, each of a plurality of terminals sequentially transmits control packets in response to a request for call before sequentially transmitting message packets. A switching node of the network is responsive to the control packets for establishing first and second logical channels through the network. Message packets are propagated through the first logical channel. The established logical channels are monitored to detect an abnormal condition. In the event of an abnormal condition in the first logical channel the message packets are re-routed to the second logical channel.

Claims

1. A packet-switched communications network, comprising:

a plurality of terminals each being capable of sequentially transmitting control packets in response to a request for a call and subsequently transmitting message packets in succession; and

a plurality of switching nodes connected to one or more of said terminals, each of said switching nodes having means responsive to said control packets for establishing first and second virtual circuits from a source terminal to a destination terminal, means for detecting whether an abnormal condition exists in said first virtual circuit, and means for writing routing information of said first virtual circuit into said message packets to enable same to be propagated through said first virtual circuit and rewriting said routing information of said message packets with routing information of said second virtual circuit when said abnormal condition is detected in said first logical channel.

2. A packet-switched communications network, comprising:

a plurality of terminals each sequentially generating control packets bearing source and destination address information on a source terminal and a destination terminal before interactive communication begins therebetween and sequentially transmitting message packets each having a routing information field; and

a plurality of switching nodes, each comprising;

a memory;

control means for deriving incoming and outgoing routing information on first and second logical channels from the source and destination address information in said control packets, writing the derived outgoing routing information into said memory, establishing said first and second logical channels from said source terminal to said destination terminal in accordance with the derived outgoing routing information, causing said source terminal to write the derived incoming routing information into the routing information field of each of the message packets, rewriting the routing information field of each of the message packets from said source terminal with the outgoing routing information stored in said memory concerning one of said established logical channels, and enabling said message packets to be propagated through said one of said established logical channels in accordance with the outgoing routing information contained therein; and

detector means for detecting an abnormal condition in said first and second logical channels and causing said source terminal to rewrite the routing information field of subsequent message packets with the incoming routing information on the other of said established logical channels when said abnormal condition is detected in the packet-propagating logical channel to thereby allow said subsequent message packets to be switched over to said other established logical channel.

3. A packet-switched communications network, comprising:

a plurality of terminals each sequentially generating control packets bearing source and destination address information on a source terminal and a destination terminal before interactive communication begins therebetween and sequentially transmitting message packets each having a routing information field; and

a plurality of switching nodes, each comprising;

a memory;

control means for deriving incoming and outgoing routing information on first and second logical channels from the source and destination address information in said control packets, writing the derived outgoing routing information into said memory, establishing said first and second logical channels from said source terminal to said destination terminal in accordance with the derived outgoing routing information, causing said source terminal to write the derived incoming routing information into the routing information field of each of the message packets, rewriting the routing information field of each of the message packets from said source terminal with the derived outgoing routing information stored in said memory concerning one of said established logical channels, and enabling said message packets to be propagated through said one of the established logical channels in accordance with the outgoing routing information contained therein; and

detector means for detecting an abnormal condition in said first and second logical channels and rewriting said memory with the outgoing routing information of the other of said established logical channels when said abnormal condition is detected in the packet-propagating logical channel to thereby allow subsequent message packets to be switched over to said other established logical channel.

4. A packet switching system comprising:

a bus;

a plurality of line controllers connected to said bus, each being responsive to control packets and message packets, said message packets having an incoming logical address and an incoming physical address, each of said line controllers including a memory for storing a first set of outgoing logical and physical addresses in a first location and a second set of outgoing logical and physical addresses in a second location, said first and second locations being respectively accessible as a function of said incoming logical and physical addresses of the message packets, said first and second sets defining a plurality of transmission paths, means for updating the incoming logical and physical addresses of said message packets with the logical and physical addresses of an accessed one of said first and second sets, and means for coupling said updated message packets to through said bus to another one of said line controllers determined by the outgoing physical address of said message packets for application to one of said transmission paths;

a central processor for deriving said first and second sets of outgoing logical and physical addresses respectively from said control packets received via said line controllers and writing the derived sets into said memory;

means for detecting an abnormal condition in said transmission paths; and

means for causing subsequent message packets to be re-routed to another of said transmission paths if said abnormal condition occurs in said one of the transmission paths.

5. A method for transmitting packets through a communications network, comprising:

sequentially transmitting control packets from a source terminal;

establishing first and second virtual circuits from said source terminal to a destination terminal in accordance with said control packets;

writing routing information of said first virtual circuit into message packets and transmitting same from said source terminal so that the message packets are propagated through said first virtual circuit;

detecting whether an abnormal condition exists in said first virtual circuit; and

rewriting said routing information of said message packets with routing information of said second virtual circuit and transmitting same from said source terminal when said abnormal condition is detected in said first virtual circuit so that the message packets are re-routed to said second virtual circuit.

6. A method for transmitting packets through a communications network, comprising:

sequentially transmitting control packets each bearing source and destination address information on said source terminal from said source terminal;

deriving incoming and outgoing routing information on first and second logical channels from the source and destination address information in said control packets;

establishing said first and second logical channels from said source terminal to said destination terminal in accordance with the derived outgoing routing information;

generating a message packet having a routing information field and writing the derived incoming routing information into the routing information field of the message packet and transmitting it from the source terminal;

rewriting the routing information field of each of the message packets received from said terminal with the derived outgoing routing information concerning one of said established logical channels;

causing the message packets to be propagated through said one of the established logical channels in accordance with the outgoing routing information contained therein;

detecting an abnormal condition in said first and second logical channels; and

rewriting the routing information field of subsequent message packets with the incoming routing information on the other of said established logical channels when said abnormal condition is detected in the packet-propagating logical channel to thereby allow said subsequent message packets to be switched over to said other established logical channel.

7. A method for transmitting packets through a communications network, comprising:

sequentially transmitting control packets each bearing source and destination address information on said source terminal from said source terminal;

deriving incoming and outgoing routing information on first and second logical channels from the source and destination address information in said control packets;

writing the derived outgoing routing information into a path memory;

establishing said first and second logical channels from said source terminal to said destination terminal in accordance with the derived outgoing routing information;

generating a message packet having a routing information field and writing the derived incoming routing information into the routing information field of the message packet and transmitting it from the source terminal;

rewriting the routing information field of each of the message packets received from said terminal with the outgoing routing information stored in said memory concerning one of the established logical channels;

causing the message packets to be propagated through said one of the established logical channels in accordance with the outgoing routing information contained therein;

detecting an abnormal condition in said first and second logical channels; and

rewriting said memory with the outgoing routing information on the other of said established logical channels when said abnormal condition is detected in the packet-propagating logical channel to thereby allow subsequent message packets to be switched over to said other established logical channel.