Aim switching system and path changing method
First Claim
1. An asynchronous transfer mode (ATM) packet switching system, including:
- a packet switch having a plurality of input/output lines, and being operable to form connections between said input and output lines so that an input packet received from an input line is routed to at least one output line according to a packet header content;
a storage for each connection, having a plurality of header information corresponding to an output line for a normal time and an output line for a failure time, respectively;
a selector, for each input packet, selecting and reading out at least one header information stored in said storage in accordance with the presence or absence of a failure on the output line for a normal time;
a header conversion unit for converting the content of the header portion of said input packet on the basis of the header information selected and read out by said selector; and
said packet switch forming a connection to output the output packet to the output line corresponding to the header portion of the output packet.
1 Assignment
0 Petitions
Accused Products
Abstract
An ATM switching system at each node of a network performs route changing or rerouting promptly when a failure occurs. In each of ATM switching systems at nodes N1 to N6: a route table 21 of a line interface 102 is set with conversion header information of a normal route, and an alternate routing table 25 is set with header information of one or more alternate routes. Subsequently, each line interface tests, when a packet arrives, whether or not a failure has occurred in an output line involved in the normal route, by referring to a bitmap 264 storing failure lines and a VP failures. The line interface executes header conversion by applying the normal header information stored in the routing table 21 in the case of no failure set for the normal route and by applying the header information stored in the alternate routing table 25 in case a failure has occurred on the normal route, and then outputs the packet to an ATM switch 101. Since the alternate route is promptly selected at the time of a failure of a net line and not in response to decoding a header of a received packet, the number of packets discarded due to the failure is reduced, and the rerouting operation is promptly executed even in the case of multiple failures.
-
Citations
22 Claims
-
1. An asynchronous transfer mode (ATM) packet switching system, including:
-
a packet switch having a plurality of input/output lines, and being operable to form connections between said input and output lines so that an input packet received from an input line is routed to at least one output line according to a packet header content; a storage for each connection, having a plurality of header information corresponding to an output line for a normal time and an output line for a failure time, respectively; a selector, for each input packet, selecting and reading out at least one header information stored in said storage in accordance with the presence or absence of a failure on the output line for a normal time; a header conversion unit for converting the content of the header portion of said input packet on the basis of the header information selected and read out by said selector; and said packet switch forming a connection to output the output packet to the output line corresponding to the header portion of the output packet. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
9. An asynchronous transfer mode (ATM) packet switching system comprising:
-
a switch having a plurality of input and output ports to be connected to input/output lines; a plurality of line interfaces connected between said input and output ports and the input/output lines; a call controller connected with each of said line interfaces and said switch to control switch connection between said input and output ports, so that an input packet received from an input line is routed to at least one output port as determined according to content of a header portion of the packet; each of said line interfaces including; first header generating means for generating and storing first header information to route the input packet to the output port along a route designated in advance as a normal route in a manner to correspond to one of said connections, wherein said storing is completed prior to said line interface receiving the input packet; second header generating means for generating and storing second header information to route the input packet to another output line along another route designated in advance as an alternate route in a manner to correspond to another of said connections, wherein said storing is completed prior to said line interface receiving the input packet; and header conversion means for converting the header portion of each input packet to include the first header information when the output lines of the normal route are normal, and to include the second header information when there is a failure on the output line of said normal route; and wherein said switch forms said one or another connection that transfers the input packet, received from the input line, to the output line corresponding to the header information applied by said header conversion means. - View Dependent Claims (10, 11, 12)
-
-
13. An output path changing method performed in an asynchronous transfer mode (ATM) of a packet switching system forming connections between a plurality of input and output lines, comprising the steps of:
-
at a connection setting time, designating one route with one output line as a normal route and at least another route with another output line as an alternate route and storing of a plurality of header information to be applied to header conversion of input packets in a manner to correspond to said normal route and alternate route; thereafter, each time an input packet is received from one of the input lines, retrieving from storage the header information corresponding to the normal route or alternate route selectively and using retrieved header information for the header conversion of the input packet in response to presence or absence of a failure on the output lines of the normal route; and outputting the input packet through the switch to the output line corresponding to the header information applied by said header conversion. - View Dependent Claims (14, 15, 16, 17)
-
-
18. An ATM layer process or to be inserted into input line of an asynchronous transfer mode (ATM) node system having a plurality of input/output lines, comprising:
-
first header generating means for generating and storing first header information to be applied to a normal header conversion in a manner to correspond to a connection to a normal output line, wherein said storing is completed prior to said line interface receiving the input packet; second header generating means for generating and storing second header information to be applied to a header conversion when a failure occurs on an output line, in a manner to correspond to an alternate connection, wherein said storing is completed prior to said line interface receiving the input packet; and header conversion means for converting the header portions of individual input packets selectively in a manner to correspond to the input packet received from the input line, by applying the first header information generated by said first header generating means when the normal output line is normal, and by applying the second header information generated by said second header generating means when a failure occurs on the normal output line. - View Dependent Claims (19, 20, 21, 22)
-
Specification