Abstract:
A compressed switch data storage for a network system is disclosed. The system includes a plurality of network channels to transfer data, and devices coupled to the plurality of network channels. The devices provide or receive data. The system also includes a switch. The switch has a memory for storing compress data, and a plurality of ports coupled to the plurality of network channels. The switch routes data from one port to another port according to a destination port address.

Description:
CLAIM OF PRIORITY 
   This application is a continuation application and claims priority under 35 USC §120 to U.S. patent application Ser. No. 09/609,564, filed Jun. 30, 2000 now U.S. Pat. No. 6,728,778, and entitled “LAN SWITCH WITH COMPRESSED PACKET STORAGE”, the contents of which is incorporated by reference. 

   BACKGROUND 
   The present disclosure generally relates to network switching and more specifically, to compressed data storage in network switching. 
   Networking allows computers to share resources, access information, communicate via e-mail, share data, and transfer files. However, networking technology and digital data transmission have been subject to a number of bandwidth and speed limitations due to a growing population of network users. Other factors that contribute to congestion include faster CPUs, faster operating systems, and more network-intensive applications. 
   Switching alleviates congestion in networks such as the Local Area Network (LAN) by reducing traffic and increasing bandwidth. The term switching refers to a technology in which a device, referred to as a switch, connects two or more network segments. A switch receives a packet of data from one segment, examines the embedded address information, and transmits the data packet to designated destinations on other segments. 
   The received data packet is often stored for a short period of time before being forwarded to the destination. The storage area is referred to as a packet buffer or packet data memory. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Different aspects of the disclosure will be described in reference to the accompanying drawings wherein: 
       FIG. 1  illustrates a network system such as the LAN system in accordance with an embodiment; and 
       FIGS. 2A and 2B  show a flowchart of a LAN switching process in accordance with an embodiment. 
   

   DETAILED DESCRIPTION 
   A Local Area Network (LAN) system often provides information exchange over shorter distances than a Wide Area Network (WAN) system. A LAN system may operate at higher speeds than the WAN system. Furthermore, hardware used in LAN systems is generally discrete, controlled, and homogeneous, which provides an advantageous environment for high-speed operation. Therefore, data packets in a LAN system are transmitted in an uncompressed format. 
   Accordingly, packets are stored in the buffer area in an uncompressed format. However, the memory buffer may need to be relatively large in size to store the uncompressed data packets. 
     FIG. 1  illustrates a network system such as the LAN system  100  in accordance with an embodiment. In the illustrated embodiment, the LAN system  100  includes a switch chip  102 , a plurality of devices A through L, and a plurality of ports  104 – 110 . The switch  102  includes memory  112  that may store the data packets in a compressed format. Compressing the data packets may reduce the amount of memory required for the packet buffer. The smaller memory size may enable the memory  112  to be embedded into the same die as the switch chip  102 . 
   Each device on the LAN system  100  has a media access control (MAC) address, which uniquely identifies the device to the network. The device may be a computer, processor, printer or other peripherals capable of storing and exchanging information. The device may serve as a client or a server. The term “client” refers to a device&#39;s general role as a requester of data or services, and the term “server” refers to a device&#39;s role as a provider of data or services. The size of a computer, in terms of its storage capacity and processing capability, does not necessarily affect its ability to act as a client or server. Further, it is possible that a device may request data or services in one transaction and provide data or services in another transaction, thus changing its role from client to server or vice versa. 
   The data packets are delivered, and origination devices are recognized by MAC addresses on the packets. The switch  102 , and each port  104 – 110  on the switch  102 , supports a finite number of MAC addresses. However, the overall number of addresses for the switch  102  may be large, so that the switch  102  can support a large number of devices. In the illustrated embodiment of  FIG. 1 , the number of ports (n) may be large. 
   In  FIG. 1 , each LAN segment  120 – 126  is connected to a port  104 – 110  on the LAN switch chip  102 . If server A on port # 1   104  needs to transmit to client D on port # 2   106 , the LAN switch chip  102  forwards data packets from port # 1   104  to port # 2   106 . Ports # 3   108  through #n  110  may be isolated from the data traffic between port # 1  and port # 2 . 
   If server I needs to send data to client L at the same time that server A sends data to client D, the server I may do so because the LAN switch chip  102  can forward data packets from port # 3   108  to port #n  110  at the same time it is forwarding data packets from port # 1   104  to port # 2   106 . If server A on port # 1   104  needs to send data to client C, which is also on port # 1   104 , the LAN switch chip  102  does not need to forward any packets. Thus, the switch chip  102  alleviates data traffic congestion on the LAN system. The switch chip  102  may also increase the bandwidth by simultaneously routing data between more than one pair of switch chip ports. 
   In some embodiments, the switch chip  102  may transfer compressed data packets internally. In other embodiments, the switch chip  102  may transfer compressed data packets along an extended system backplane before decompression and transmission to the destination port. 
   The memory  112  in the switch chip  102  is configurable to store the packet data in a specified configuration. 
   A flowchart of a LAN switching process in accordance with an embodiment is illustrated in  FIGS. 2A and 2B . An incoming packet of data is received at  200 . At  202 , a destination MAC address may be extracted from the packet. The data packet is compressed at  204 . The compressed data packet is stored in a packet memory at  206 . 
   A lookup table in the memory is accessed at  208 . The lookup table provides port addresses corresponding to the MAC addresses of the devices. A lookup engine searches the table to determine the switch port corresponding to the destination MAC address at  210 . 
   Once the corresponding port is identified, the packet is posted to the appropriate queue at  212 . When the packet rises to the top of the queue at  214 , the packet may be forwarded to the output port at  216 . The packet may then be decompressed for transmission at  218  and cleared from memory. The decompressed data packet is transmitted to the destination address via the port address from the lookup table at  220 . 
   The advantages of providing a LAN switch chip with a built-in memory having compressed packet data include low cost and decreased chip count. By storing the packet data in the switch chip, a need for external memory devices is reduced or eliminated. Further, the consolidation reduces the chip manufacturer&#39;s dependence on third party memory suppliers. 
   While specific embodiments of the invention have been illustrated and described, other embodiments and variations are possible. For example, although the switch configuration has been described in terms of an integrated switch chip with embedded memory, the system may be implemented with separate chips for switching fabric, memory and physical layer port interfaces. 
   All these are intended to be encompassed by the following claims.