Electrical computers and digital processing systems: multicomput – Computer-to-computer protocol implementing – Computer-to-computer data transfer regulating
Reexamination Certificate
1999-11-30
2001-12-04
Etienne, Ario (Department: 2155)
Electrical computers and digital processing systems: multicomput
Computer-to-computer protocol implementing
Computer-to-computer data transfer regulating
C709S220000, C709S250000, C710S052000, C710S120000
Reexamination Certificate
active
06327625
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to computer networks and to interface devices for connecting host computers to networks. More particularly, the present invention relates to the management of data traffic through network interface cards in network connected systems.
2. Description of Related Art
Computer systems include network interfaces that support high speed data transfer between the host computer and the data network. These network interfaces are typically based on a first-in-first-out (FIFO) buffer. Thus, packets coming onto the network interface, either from the network or from the host computer are stored in the FIFO. The first packet into the FIFO is transmitted out first in order to maintain sequential data transfers. The FIFO structure is an efficient, high throughput system for managing high speed network interfaces such as Gigabit Ethernet interfaces.
As computer networks are adapted to carry a variety of types of traffic, network protocols are being developed to support variant processing of packets as they traverse the network. Thus, priority packets are developed which are suitable for carrying real-time video or audio signals. These priority packets are processed ahead of other packets in sequence when possible to improve the throughput and reduce the latency of processing for this class of packet. Also, network security is supported for some types of packets. Thus, the Internet security IPsec protocols are being developed. (Request For Comments, 2401 Security Architecture for the Internaet Protocol, Internet Engineering Task Force). According to security protocols, the payload and/or the header and other control data associated with the packet are protected using authentication and encryption processes. Accordingly, a variety of priority schemes and other schemes involving processing of packets according to particular processes like encryption through the network have been developed.
The FIFO structure in network interface cards suffers the disadvantage that it is inflexible in the sequence of processing of packets being transferred through the interface, that is, a FIFO structure supports only sequential data transfer. Each packet being loaded will be unloaded through the same sequence determined by the order of receipt of the packet into a typical FIFO-based network interface. Therefore, the processing of packets according to protocols which may benefit from processing out of order must be executed before the packets are delivered to the network interface, or after the packets leave the network interface.
Accordingly, it is desirable to provide techniques for improving the flexibility of network interfaces, while maintaining the efficient character of FIFO structures.
SUMMARY OF THE INVENTION
The present invention provides support for priority and Internet Protocol security packets, and other protocols at the network interface level and in conjunction with FIFO-based packet buffers. The present invention supports such protocols by allowing out of order processing of certain packets in the FIFO. In this manner, the optimized character of FIFO for sequential transfer is maintained, while particular types of packets are processed out of order to achieve minimum latency and maximum data security in an intelligent network interface card.
One aspect the present invention is a computer system that comprises a host processor and a network interface having a first port coupled to the host processor and a second port adapted for at least one of receiving data from and transmitting data to a network. A buffer is coupled to the first and second ports and stores data packets from one of the first and second ports in an order of receipt, said packets identifiable as having respective packet types from a plurality of packet types. Logic is included in the network interface to transfer packets out of the buffer to the other of the first and second ports according to the order of receipt, and according to the respective packet types so that packets having a particular packet type are transferred out of the order of receipt relative to packets having other packet types.
In one embodiment, a data filter is coupled with the buffer to generate identifiers identifying packets of data stored in the buffer as members of one of a plurality of packet types. Logic maintains a list of packets stored in the buffer having a particular packet type. The logic to transfer the packets is responsive to the list to determine the order in which a given packet is transferred out of the buffer. Thus for example, priority packets are identified and entries placed in a queue of priority packets on the network interface. Packets identified in the queue are transferred out of the buffer ahead of other packets not identified in the queue. When the queue is empty, packets of other types are transferred out of the buffer. Also when the queue is not empty, but the buffer approaches a fullness threshold, packets of other types may be flushed from the buffer to minimize data overruns and other errors in the transfer of the packets.
In another embodiment, packets of the particular types are suitable for processing according to a process such as an encryption or authentication process. Such packets are identified and read out of the buffer for such processing. A control parameter is associated with the packet which indicates whether such processing has completed and whether the packet is ready for transfer. Logic which transfers packets out of the buffer is responsive to the control parameter to skip the packet and transfer a following packet in the buffer out of order. When the processing is complete, the control parameter is updated and the logic transferring packets out of the buffer is notified that the skipped packet may be transferred.
In yet another embodiment, the logic to transfer the packet includes processing resources which perform, in various combinations and orders, the following functions:
set up a control field for each packet stored in the buffer in an order of receipt;
write a parameter in the control field indicating the packet type has one of a plurality of packet types, including a first packet type, a second packet type and a third packet type;
write a parameter in the control field indicating whether the packet has already been transferred;
maintain a queue of entries identifying packets having the third packet type;
process packets having the second packet type according to a particular process;
write a parameter in the control field for packets having the second packet type indicating whether the packet is ready for transfer and the processing according to the particular process is complete;
maintain an indicator of fullness of the buffer; and
transfer a packet from the buffer according to a priority rule which
causes transfer of a packet identified by an entry in the queue ahead of packets in the buffer having the first and second packet types relative to the order of receipt,
causes transfer of a packet having the first packet type in the order of receipt of the packet, if the parameters in the control field indicate the packet is ready for transfer, and the queue of entries is empty or the indicator of fullness exceeds a threshold, and
skips transfer of a packet having the second packet type relative to the order of receipt if the parameter in the control field indicates the processing is not complete.
In other embodiments, the invention comprises a network interface, an integrated circuit for use in a network interface, and a processing method for transferring packets through the network interface.
The present invention improves network interfaces based on FIFO buffer structures. Priority packets and packets such as IPSec packets can be marked in a header using packet filter logic. Priority packets can be transmitted or uploaded prior to normal packet traffic. Also, if the FIFO space is near a full threshold, the priority packet transfer is temporarily suspended. Normal packets in the FIFO ahead of priority packets can be unloa
Ho Ngo Thanh
Wang Chi-Lie
Yang Li-Jau
3Com Corporation
Etienne Ario
Haynes Mark A.
Haynes Beffel & Wolfeld LLP
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