Multiplex communications – Data flow congestion prevention or control – Control of data admission to the network
Reexamination Certificate
2000-03-23
2004-12-07
Marcelo, Melvin (Department: 2663)
Multiplex communications
Data flow congestion prevention or control
Control of data admission to the network
Reexamination Certificate
active
06829219
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a routing processing method in a packet transmission and a system therefore. More particularly, the invention relates to a routing processing method in a packet transmission and a system therefore, for performing delay control of a packet in an internet telephone communication in a Transmission Control Protocol/Internet Protocol (TCP/IP) network.
2. Description of the Related Art
Conventionally, a router disposed in the CP/IP network of this type (such as intranet, intemet, extranet, hereinafter only referred to intemet) retrieves a routing table from a destination address to read out a data transmission path to a transmission destination for transmitting a packet to the read out transmission path. In this case, packet transmission cannot be carried out until completion of routing retrieval. Therefore, a transmission period of the packet is significantly variable depending upon a retrieval period of the routing table.
In the recent internet performing packet transmission, a best effort type service is typical. The best effort type service is a service to do the best effort for accomplishing a processing considering the entire network but does not guarantee end-to-end service. Therefore, in the worst case, service cannot be provided. The recent internet is apt to exceed traffic in the existing wired and radio telephone services. As a result, even in the intemet which has provided the best effort type service conventionally, a service quality (Qos: quality of service) comparable with the conventional type communication network is require to be realized.
In such TCP/IP communication network, guarantee for delay of packet transmission is becoming important. Particularly, in the case of transmission telephonic speech (talk signal) in a form of a packet, clarity of telephonic conversation can be degraded to make delay unacceptable if end-to-end delay becomes in excess of about 100 msec. Accordingly, it becomes necessary to restrict the delay of packet transmission in the TCP/IP communication network to be a predetermined value or less. In such TCP/IP communication network, one of the important causer of packet transmission delay is the routing process in the router. Accordingly, when a processing amount in the routing process in the router is large (upon a high load condition) and when the routing process cannot be performed at high speed, it becomes impossible to restrict the delay to be less than or equal to the predetermined value.
Various proposals have been made for the routing process of this kind. For example, in Japanese Unexamined Patent Publication No. Heisei 4-183044, for “Routing Control System with Modification of Transmission Source Data”, correction of a user data of a transmitted PUD (Protocol Unit Data) can be corrected only by transmitting a user data modification PUD within a transmission holding period when correction becomes necessary after transmission of PUD containing the large amount user data by a transmission source end system or when the correction amount is small.
On the other hand, in Japanese Unexamined Patent Publication No. Heisei 6-244867, for “Back-up Route Connection Stand-by Routing System”, connection of a backup path is conditioned upon the occurrence of a failure in a junction line. In this method, real-time routing depending upon the condition of the back-up path is enabled, and in conjunction therewith, traffic and node load in the network can be reduced. Furthermore, by restricting increase of the number of junction stages, the possibility of abandonment or dropping of packets can be reduced. In addition, by preventing the back-up path from unnecessarily opening, the communication period can be reduced to reduce wasting of communication cost.
As set forth above, in the prior art, delay in packet transmission due to the routing process in the router is caused in the communication network. If the amount of routing process in the router is large for high load and thus the routing process cannot be executed at high speed, it becomes impossible to restrict the delay for internet telephone communication to be less than or equal to the allowable predetermined value.
SUMMARY OF THE INVENTION
The present invention has been worked out in view of the problem in the prior art as set forth above. It is therefore an object of the present invention to provide a routing process in a packet transmission and a system therefor, which does not effect abandonment of packet for an application not given importance for a delay value to restrict delay in the routing process adapting to the application for enabling reduction of process period required for routing process.
In order to accomplish the above-mentioned object, according to the first aspect of the present invention, a routing processing method in a packet transmission for an input packet as an object for routing, comprises the steps of:
performing a process for identifying an application adapting for transmission of an input packet;
performing a process for setting a timer value preliminary provided for the identified application:
performing a process for routing to determine a port of transmission destination on the basis of a destination address stored in a routing table; and
performing a process for abandoning a packet or transferring the packet to a predetermined route adapting the identified application when routing process cannot be completed exceeding the set timer value.
According to the second aspect of the present invention, a packet transmission routing processing system performing a routing process for an input packet as a routing object, comprises:
parsing and timer processing means for identifying an application corresponding to transmission of an input packet and monitoring a timer value preliminary provided for the application; and
routing and transferring means for determining a port of a transmission destination on the basis of a destination address stored in a routing table and disposing the packet or transferring the packet to a preliminary determined route adapting to the identified application when routing process is continued beyond the timer value monitored by the parsing and timer processing means.
In the preferred construction, the parsing and timer processing means and the routing and transferring processing means may comprise:
a packet accumulating portion accumulating the input packet;
a packet parsing portion performing parsing for identifying the application corresponding to the packet from the packet accumulating portion and reading out of a destination address;
a packet waiting portion waiting the packet from the packet parsing portion and transmitting the packet in response to a packet output command;
packet transferring portion for transferring the packet output from the packet waiting portion to a packet output port on the basis of a transmission destination designation and next process designation;
a timer value determining portion outputting a timer value and a next process code corresponding to the application identified by the packet parsing portion;
a monitoring timer portion outputting a time out signal upon termination of measurement of the timer value from the timer value determining portion; and
a routing retrieving portion outputting a packet output designation signal to the packet waiting portion and outputting a transfer path number and a process code to the packet transferring portion when the routing process based on the destination address from the timer value parsing portion or a time out signal is input from the monitoring timer portion.
The timer value may be a timer for executing a predetermined process when routing retrieval is not completed within a period designated by the timer value, and
the next processing code may be a code designating the process of packet to be object for the routing process when retrieving process in the routing retrieving portion is not completed within the period designated by the timer value.
The predetermined process in the
Honda Masahiko
Sera Takafumi
Foley & Lardner LLP
Marcelo Melvin
NEC Corporation
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