Patent Publication Number: US-8121035-B2

Title: Apparatus and method for packet buffer management in IP network system

Description:
CLAIM OF PRIORITY 
     This application makes reference to and claims all benefits accruing under 35 U.S.C. §119 from an application for “APPARATUS AND METHOD FOR PACKET BUFFER MANAGEMENT IN IP NETWORK SYSTEM” earlier filed in the Korean Intellectual Property Office on Feb. 12, 2007 and there duly assigned Serial No. 2007-0014294. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus and method for packet buffer management in an Internet Protocol (IP) network system. 
     2. Description of the Related Art 
     One of required features of next-generation Internet is high reliability. 
     With an increase of higher value-added mission-critical traffic, real-time traffic, and high-priority traffic, a need for stably servicing the traffics is increasing. 
     As a network evolves into a high speed and large capacity network, the network processes much more data transmission. This leads to traffic congestion in a network zone, causing a loss of user data and causing the degradation of performance between end-to-end users. 
     The Next generation of the Internet basically requires an efficient and effective mechanism for, upon the occurrence of network failure, detecting the failure within a short time, recovering from the failure within a short time, and continuing to provide a service. 
     Thus, even when congestion occurs at a specific link of a network due to a flood of user traffic, it can be regarded as another cause of a network failure. 
     In the event that an amount of user data flooding in a link corresponding to an optimal path exceeds an optimal transmission degree of the link, user data may be lost. Such a loss of user data leads to data re-transmission between end-to-end networks, affecting a quality of network service. 
     Thus, when congestion occurs because of the flood of user data, how long time packets are stored with no packet loss for each link is considered a factor of significance. 
     In a conventional network system, when traffic floods into a specific zone of a network and congestion occurs at a corresponding port, packets are processed as much as they can be stored in a packet queue for each corresponding port and other packets exceeding a storage capacity are dropped. Undoubtedly, a variety of algorithms such as Random Early Detection (RED) and Weighted RED (WRED) have been developed as a packet drop way. 
     However, how long time packets can be stored before being dropped is basically a factor of significance. For this, there is needed a consideration for how efficiently a limited packet buffer is managed. 
       FIG. 1  shows a management scheme for a packet buffer allocated every link and used in a conventional network system. 
     Assuming that there are ‘m’ number of queues at a link and the queue has the limited ‘n’ number of packet buffers, each queue is set, at the time of initial system driving, to store the maximum ‘n/m’ number of packet buffers. If congestion occurs at the link, packets exceeding the ‘n/m’ number are dropped. 
     SUMMARY OF THE INVENTION 
     The present invention solves the foregoing problems with the prior art and therefore the present invention provides an apparatus and method for packet buffer management in an IP network system, for efficiently managing a limited packet buffer. 
     According to an aspect of the invention for realizing the above objects, there is provided an apparatus for packet buffer management in an IP network system with at least one port having an internal queue. The apparatus includes at least one link queue buffer, a shared buffer, a buffer state detector, and a buffer manager. The at least one link queue buffer is allocated to a buffer of a packet stored in a memory to transmit the packet. The shared buffer is excessively allocated when exceeding a minimum buffer threshold value of the link queue buffer. The buffer state detector determines whether a buffer value stored in a link queue buffer of a corresponding link exceeds a preset minimum buffer threshold value. The buffer manager sets the shared buffer to be included in the link queue buffer of the link if the buffer value stored in the link queue buffer of the link exceeds the preset minimum buffer threshold value. 
     The link queue buffer and the shared buffer may be set with buffer values divided within the capacity of a memory storing a packet. 
     According to another aspect of the invention for realizing the above objects, there is provided a method for buffer management in a network system using a link queue buffer and a shared buffer. The method includes steps of: upon selecting a packet transmission link, determining whether the number of buffers being on transmission standby in a corresponding link queue buffer exceeds a minimum buffer threshold value; setting the shared buffer as the corresponding link queue buffer if the number of buffers being on transmission standby in the corresponding link queue buffer exceeds the minimum buffer threshold value; and allocating the shared buffer to a packet to be transmitted. 
     The method may further include, if the number of buffers being on transmission standby in the corresponding link queue buffer does not exceed the minimum buffer threshold value, allocating the link queue buffer to a packet to be transmitted. 
     The step of allocating the shared buffer to the packet to be transmitted may include steps of: determining whether there remains a packet buffer in the shared buffer; and allocating the shared buffer to a buffer of a packet to be transmitted if there remains the packet buffer in the shared buffer. 
     The method may further include, if there does not remain the packet buffer in the shared buffer, dropping a corresponding packet. 
     The link queue buffer and the shared buffer may be set with buffer values divided within the capacity of a memory storing a packet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
         FIG. 1  is a diagram illustrating a conventional packet management scheme in an IP network system; 
         FIG. 2  is a block diagram illustrating construction of an apparatus for packet buffer management in an IP network system according to the present invention; 
         FIG. 3A  is a diagram illustrating a minimum setting state of a link queue buffer and a shared buffer in the packet buffer management apparatus of  FIG. 2 ; 
         FIG. 3B  is a diagram illustrating a state where a link queue buffer and a shared buffer in the packet buffer management apparatus of  FIG. 2  are concurrently used; 
         FIG. 4  is a flow diagram illustrating a method for packet buffer management in an IP network system according to the present invention; and 
         FIG. 5  is a flow diagram illustrating a process of allocating a shared buffer in the packet buffer management method of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of an apparatus and method for packet buffer management in an IP network system of the invention are shown. It will be understood by those having an ordinary knowledge in the art that a system described below is merely exemplified for describing the invention with no limit to the scope of the present invention. 
       FIG. 2  is a block diagram illustrating construction of an apparatus for packet buffer management in an IP network system according to the present invention. The packet buffer management apparatus includes at least one link queue buffer  100 , a shared buffer  200 , a buffer state detector  300 , and a buffer manager  400 . The packet buffer management apparatus further includes an enqueuing block  10 , a dequeuing block  20 , and a memory  30 . 
     The enqueuing block  10  enqueues a packet to a packet queue buffer of each link to have to transmitted the packet. 
     The dequeuing block  20  identifies an address of the packet from the packet queue buffer, then takes the packet out of a memory  30  using the packet address identified through the packet queue buffer, and then transmits the packet outside the link. 
     The memory  30  stores a packet to be transmitted. The memory  30  includes a link queue buffer  100  and a shared buffer  200 . The link queue buffer  100  enqueues a buffer having address information on a packet that is stored in a corresponding link queue buffer through the enqueuing block  10 . 
     The link queue buffer  100  is allocated to a buffer of a packet stored in the memory  30  used to transmit the packet. 
     The shared buffer  200  is allocated when exceeding a minimum buffer threshold value of at least one link queue buffer  100 . The link queue buffer  100  and the shared buffer  200  are set with buffer values divided within the capacity of a memory storing a packet. 
     The buffer state detector  300  determines whether a buffer value stored in a link queue buffer  100  of a corresponding link exceeds a preset minimum buffer threshold value. 
     If the buffer value stored in the link queue buffer  100  of the link exceeds the minimum buffer threshold value, the buffer manager  400  sets the shared buffer  200  to be included in the link queue buffer  100  of the link. 
     A detailed description of general function and operation of each of the elements is omitted and a description of operation of the invention is made below. 
     First, the buffer manager  400  sets a minimum buffer threshold value to the link queue buffer  100 . In detail, as shown in  FIG. 3A , at least one link queue buffer  100  is allocated to the minimum buffer threshold value and then, the shared buffer  200  is allocated to a remaining buffer amount. 
     After that, when a queue number is set to a link queue buffer  100  to queue a packet to have to be transmitted outside, the buffer state detector  300  reads current queue state information (the number of packets and a minimum buffer threshold value currently stored in a queue) of the link queue buffer  100 . 
     Next, the buffer state detector  300  compares the number of packets stored in the link queue buffer  100  with the minimum buffer threshold value of the queue. 
     If the number of packets of the link queue buffer  100  exceeds the preset minimal buffer threshold value, the buffer manager  400  uses the shared buffer  200 , without regard for setting of the minimum buffer threshold value of the link queue buffer  100 , as shown in  FIG. 3B . That is, if the link queue buffer  100  is fully allocated to packets, the shared buffer  200  is used as the link queue buffer  100 . Thus, if a packet has to be transmitted outside is generated, the packet is allocated to the shared buffer  200 . 
     By doing so, packets can be prevented from being lost due to the limitation of the capacity of the link queue buffer  100 . 
     If there does not remain sufficient room to store a packet even in the shared buffer  200 , the packet is dropped. 
     If the number of packets of the link queue buffer  100  does not otherwise exceed the preset minimum buffer threshold value, the buffer manager  400  allocates a packet to the link queue buffer  100  without using the shared buffer  200  when the buffer manager  400  identifies that there remains a room to allocate the packet in the link queue buffer  100  using the buffer state detector  300 . 
     A method for packet buffer management in the IP network system according to the present invention is described with reference to  FIG. 4 . 
     First, if a packet transmission link is selected, the method determines whether the number of buffers being on transmission standby in a corresponding link queue buffer  100  exceeds a minimum buffer threshold value of a queue (S 1 ). 
     If the number of buffers exceeds the minimum buffer threshold value, the method sets the shared buffer  200  as the link queue buffer  100  (S 2 ). 
     After that, the method allocates the shared buffer  200  to a packet to be transmitted (S 3 ). 
     The procedure (S 3 ) of allocating the shared buffer  200  to the packet to be transmitted is described in detail below with reference to  FIG. 5 . 
     First, the process determines whether there remains a packet buffer in the shared buffer  200  (S 31 ). 
     If there remains a packet buffer in the shared buffer  200 , the process allocates a packet to be transmitted to the shared buffer  200  (S 32 ). 
     If there is not enough space in the packet buffer in the shared buffer  200 , the process drops a corresponding packet (S 33 ). 
     If the number of buffers being in transmission standby state does not exceed the minimum buffer threshold value in S 1 , the process allocates the link queue buffer  100  to a packet to be transmitted (S 4 ). 
     The link queue buffer  100  and the shared buffer  200  are set with buffer values divided within a capacity of the memory storing a packet. 
     As described above, the apparatus and method for packet buffer management in the IP network system according to the present invention have an excellent effect of, upon the occurrence of congestion at the link, reducing a loss of packets caused by the congestion and finally improving a network performance in an end-to-end user zone. 
     While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.