摘要:
The present invention provides a per-flow dynamic buffer management scheme for a data communications device. With per-flow dynamic buffer limiting, the header information for each packet is mapped into an entry in a flow table, with a separate flow table provided for each output queue. Each flow table entry maintains a buffer count for the packets currently in the queue for each flow. On each packet enqueuing action, a dynamic buffer limit is computed for the flow and compared against the buffer count already used by the flow to make a mark, drop, or enqueue decision. A packet in a flow is dropped or marked if the buffer count is above the limit. Otherwise, the packet is enqueued and the buffer count incremented by the amount used by the newly-enqueued packet. The scheme operates independently of packet data rate and flow behavior, providing means for rapidly discriminating well-behaved flows from non-well-behaved flows in order to manage buffer allocation accordingly. Additionally, the present invention adapts to changing flow requirements by fairly sharing buffer resources among both well-behaved and non-well-behaved flows.
摘要:
The invention provides a single-chip method. The method includes a memory shared among packet buffers for receiving packets, packet buffers for transmitting packets, and packet header buffers for packet forwarding lookup. Accesses to that shared memory are multiplexed and prioritized. Packet reception is performed with relatively high priority, packet transmission is performed with medium priority, and packet forwarding lookup is performed with relatively low priority. The single-chip method includes circuits for serially receiving packet header information, converting that information into a parallel format for transmission to an SRAM for lookup, and queuing input packets for later forwarding at an output port. Similarly, the single-chip method includes circuits for queuing output packets for transmission at an output port, receiving packet forwarding information from the SRAM in a parallel format, and converting packet header information from output packets into a serial format for transmission. The single-chip method also includes a region in its shared memory for a packet forwarding table, and circuits for performing forwarding lookup responsive to packet header information.
摘要:
The invention provides an enhanced datagram packet switched computer network. The invention processes network datagram packets in network devices as separate flows, based on the source-destination address pair in the datagram packet. As a result, the network can control and manage each flow of datagrams in a segregated fashion. The processing steps that can be specified for each flow include traffic management, flow control, packet forwarding, access control, and other network management functions. The ability to control network traffic on a per flow basis allows for the efficient handling of a wide range and a large variety of network traffic, as is typical in large-scale computer networks, including video and multimedia traffic. The amount of buffer resources and bandwidth resources assigned to each flow can be individually controlled by network management. In the dynamic operation of the network, these resources can be varied—based on actual network traffic loading and congestion encountered. The invention also teaches an enhanced datagram packet switched computer network which can selectively control flows of datagram packets entering the network and traveling between network nodes. This new network access control method also interoperates with existing media access control protocols, such as used in the Ethernet or 802.3 local area network. An aspect of the invention is that it does not require any changes to existing network protocols or network applications.
摘要:
A method and apparatus for an enhanced datagram packet switched computer network is disclosed. The invention processes network datagram packets in network devices as separate flows, based on the source-destination address pair contained in the datagram packet itself. As a result, the network can control and manage each flow of datagrams in a segregated fashion. The processing steps that can be specified for each flow include traffic management, flow control, packet forwarding, access control, and other network management functions. The ability to control network traffic on a per flow basis allows for the efficient handling of a wide range and a large variety of network traffic, as is typical in large-scale computer networks, including video and multimedia type traffic. The amount of buffer resources and bandwidth resources assigned to each flow can be individually controlled by network management. In the dynamic operation of the network, these resources can be varied based on actual network traffic loading and congestion encountered.
摘要:
The invention provides an enhanced datagram packet switched computer network. The invention processes network datagram packets in network devices as separate flows, based on the source-destination address pair in the datagram packet. As a result, the network can control and manage each flow of datagrams in a segregated fashion. The processing steps that can be specified for each flow include traffic management, flow control, packet forwarding, access control, and other network management functions. The ability to control network traffic on a per flow basis allows for the efficient handling of a wide range and a large variety of network traffic, as is typical in large-scale computer networks, including video and multimedia traffic. The amount of buffer resources and bandwidth resources assigned to each flow can be individually controlled by network management. In the dynamic operation of the network, these resources can be varied—based on actual network traffic loading and congestion encountered. The invention also teaches an enhanced datagram packet switched computer network which can selectively control flows of datagram packets entering the network and traveling between network nodes. This new network access control method also interoperates with existing media access control protocols, such as used in the Ethernet or 802.3 local area network. An aspect of the invention is that it does not require any changes to existing network protocols or network applications.
摘要:
The present invention provides a per-flow dynamic buffer management scheme for a data communications device. With per-flow dynamic buffer limiting, the header information for each packet is mapped into an entry in a flow table, with a separate flow table provided for each output queue. Each flow table entry maintains a buffer count for the packets currently in the queue for each flow. On each packet enqueuing action, a dynamic buffer limit is computed for the flow and compared against the buffer count already used by the flow to make a mark, drop, or enqueue decision. A packet in a flow is dropped or marked if the buffer count is above the limit. Otherwise, the packet is enqueued and the buffer count incremented by the amount used by the newly-enqueued packet. The scheme operates independently of packet data rate and flow behavior, providing means for rapidly discriminating well-behaved flows from non-well-behaved flows in order to manage buffer allocation accordingly. Additionally, the present invention adapts to changing flow requirements by fairly sharing buffer resources among both well-behaved and non-well-behaved flows.
摘要:
The invention provides for hardware processing of ACLs and thus hardware enforcement of access control. A sequence of access control specifiers from an ACL are recorded in a CAM, and information from the packet header is used to attempt to match selected source and destination IP addresses or subnets, ports, and protocols, against all the ACL specifiers at once. Successful matches are input to a priority selector, which selects the match with the highest priority (that is, the match that is first in the sequence of access control specifiers). The specified result of the selected match is used to permit or deny access for the packet without need for software processing, preferably at a rate comparable to wirespeed. The CAM includes an ordered sequence of entries, each of which has an array of ternary elements for matching “0”, “1”, or any value, and each of which generates a match signal. The ACL entered for recording in the CAM can be optimized to reduce the number of separate entries in the CAM, such as by combining entries which are each special cases of a more general access control specifier. A router including the CAM can also include preprocessing circuits for certain range comparisons which have been found both to be particularly common and to be otherwise inefficiently represented by the ternary nature of the CAM, such as comparisons of the port number against known special cases such as “greater than 1023” or “within the range 6000 to 6500”.
摘要:
The invention provides an enhanced datagram packet switched computer network. The invention processes network datagram packets in network devices as separate flows, based on the source-destination address pair in the datagram packet. As a result, the network can control and manage each flow of datagrams in a segregated fashion. The processing steps that can be specified for each flow include traffic management, flow control, packet forwarding, access control, and other network management functions. The ability to control network traffic on a per flow basis allows for the efficient handling of a wide range and a large variety of network traffic, as is typical in large-scale computer networks, including video and multimedia traffic. The amount of buffer resources and bandwidth resources assigned to each flow can be individually controlled by network management. In the dynamic operation of the network, these resources can be varied—based on actual network traffic loading and congestion encountered. The invention also teaches an enhanced datagram packet switched computer network which can selectively control flows of datagram packets entering the network and traveling between network nodes. This new network access control method also interoperates with existing media access control protocols, such as used in the Ethernet or 802.3 local area network. An aspect of the invention is that it does not require any changes to existing network protocols or network applications.
摘要:
The invention provides a method and system for packet processing, in which a router (or switch) is capable of quickly processing incoming packets, thus performing level 2, 3, and 4 routing and additional services, in real time. A system includes a packet processing engine (PPE), having elements for receiving packets, distinguishing header and payload information for those packets, outsourcing router decision-making to additional hardware resources such as a fast forwarding engine (FFE), and forwarding those packets. The PPE is synchronized to the FFE, so that the PPE can send and the FFE can receive packets at each one of a sequence of constant-duration time quanta. Similarly, the PPE can receive and the FFE can send packet routing information at each one of a sequence of similar time quanta. The PPE and the FFE have separate hardware so that their functions can be performed in parallel without contention for operating resources.
摘要:
The present invention provides a per-flow dynamic buffer management scheme for a data communications device. With per-flow dynamic buffer limiting, the header information for each packet is mapped into an entry in a flow table, with a separate flow table provided for each output queue. Each flow table entry maintains a buffer count for the packets currently in the queue for each flow. On each packet enqueuing action, a dynamic buffer limit is computed for the flow and compared against the buffer count already used by the flow to make a mark, drop, or enqueue decision. A packet in a flow is dropped or marked if the buffer count is above the limit. Otherwise, the packet is enqueued and the buffer count incremented by the amount used by the newly-enqueued packet. The scheme operates independently of packet data rate and flow behavior, providing means for rapidly discriminating well-behaved flows from non-well-behaved flows in order to manage buffer allocation accordingly. Additionally, the present invention adapts to changing flow requirements by fairly sharing buffer resources among both well-behaved and non-well-behaved flows.