# Patent

## Title
Transmit rate pacing of large network traffic bursts to reduce jitter, buffer overrun, wasted bandwidth, and retransmissions

## Abstract

A system, method and medium is disclosed which includes selecting, at a software component of a network traffic management device, a first bucket having a first predetermined transmit time. The disclosure includes populating one or more selected data packet descriptors associated with one or more corresponding data packets in the first bucket. The disclosure includes releasing the first bucket to a hardware component of the network traffic management device, wherein the hardware component processes the one or more data packet descriptors of the first bucket for the first predetermined transmit time.

## Background
FIELD
This technology relates to a system and method for pacing network traffic between network devices.
BACKGROUND
It is very common for a modern server to transmit large blocks of data in one burst to a single destination where the network path to the destination has much lower bandwidth than the really large bandwidth of the server's path within the data center and the first few hops along that path. Often these bursts are in response to a request for data, and the data is read from a storage medium (e.g., a disk) in a large block to help amortize the cost of the read operation. The large chunk of data is then dumped by the server's OS into the network at full speed, adding latency for other traffic following some portion of the same path through the network. This latency is unnecessary since other traffic could easily have been interleaved with the packets of the burst if the packets of the burst were spaced in time to match the true bandwidth of the full path to the destination. Further, such bursts can result in loss of some of the burst data due to overruns in of the buffering in the network path to the destination. Such losses necessitate retransmission of some of the large chunk of data—effectively reducing the gains that were hoped to be achieved by the batching of the read operation into a large chunk and reducing the overall throughput of the server. If the packets in these bursts were, instead, spread out in time at a pace matching the full network path data rate, both of these problems are easily solved
What is needed is a system and method which overcomes these disadvantages.
SUMMARY
In an aspect, a method for pacing data packets from one or more sessions comprises selecting, at a software component of a network traffic management device, a first bucket having a first predetermined transmit time. The method comprises populating one or more selected data packet descriptors associated with one or more corresponding data packets in the first bucket. The method comprises releasing the first bucket to a hardware component of the network traffic management device, wherein the hardware component processes the one or more data packet descriptors of the first bucket for the first predetermined transmit time.
In an aspect, a processor readable medium having stored thereon instructions for pacing data packets from one or more sessions, comprising machine executable code which when executed by at least one processor and/or network interface a network traffic management device to perform a method comprising selecting a first bucket having a first predetermined transmit time; populating one or more selected data packet descriptors associated with one or more corresponding data packets in the first bucket; releasing the first bucket to a hardware component of the network traffic management device, wherein the hardware component processes the one or more data packet descriptors of the first bucket for the first predetermined transmit time.
In an aspect, a network traffic management device comprises a memory containing non-transitory machine readable medium comprising machine executable code having stored thereon instructions for pacing data packets from one or more sessions. A network interface configured to communicate with one or more servers over a network. A processor coupled to the network interface and the memory, the processor configured to execute the code which causes the processor to perform, with the network interface, a method comprising: selecting a first bucket having a first predetermined transmit time; populating one or more selected data packet descriptors associated with one or more corresponding data packets in the first bucket; releasing the first bucket to a hardware component of the network traffic management device, wherein the hardware component processes the one or more data packet descriptors of the first bucket for the first predetermined transmit time.
In one or more of the above aspects, the method performs comprises selecting, at the software component, a second bucket having a second predetermined transmit time that is the same as the first transmit time of the first bucket; populating one or more selected data packet descriptors associated with one or more corresponding data packets in the second bucket; releasing the second bucket to the hardware component of the network traffic management device, wherein the hardware component processes the one or more data packet descriptors of the second bucket for the second predetermined transmit time quanta.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of an example system environment that includes a network traffic management device in accordance with an aspect of the present disclosure.
FIG. 2A is a block diagram of the network traffic management device in accordance with an aspect of the present disclosure.
FIG. 2B illustrates a block diagram of the network interface in accordance with an aspect of the present disclosure.
FIG. 2C illustrates further details of the network traffic management device in accordance with an aspect of the present disclosure.
FIG. 3 illustrates an example transmit ring or bucket in accordance with an aspect of the present disclosure.
FIG. 4 illustrates a time line of an example transmit ring or bucket in accordance with an aspect of the present disclosure.
FIG. 5 illustrates a block diagram of hardware based time enforcement in performed by a high speed bridge (HSB) priority mechanism in accordance with an aspect of the present disclosure.
FIG. 6 illustrates an example transmit time line in accordance with an aspect of the present disclosure.
FIG. 7 illustrates a flow chart of the software implementation of populating buckets with data packet descriptors in accordance with an aspect of the present disclosure.
FIG. 8 illustrates a flow chart of the software implementation of populating buckets with data packet descriptors in accordance with an aspect of the present disclosure.



While these examples are susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail preferred examples with the understanding that the present disclosure is to be considered as an exemplification and is not intended to limit the broad aspect to the embodiments illustrated.
DETAILED DESCRIPTION
FIG. 1 is a diagram of an example system environment that includes a network traffic management device in accordance with an aspect of the present disclosure. The example system environment 100 includes one or more Web and/or non Web application servers 102 (referred generally as “servers”), one or more client devices 106 and one or more network traffic management devices 110, although the environment 100 can include other numbers and types of devices in other arrangements. The network traffic management device 110 is coupled to the servers 102 via local area network (LAN) 104 and client devices 106 via a wide area network 108. Generally, client device requests are sent over the network 108 to the servers 102 which are received or intercepted by the network traffic management device 110.
Client devices 106 comprise network computing devices capable of connecting to other network computing devices, such as network traffic management device 110 and/or servers 102. Such connections are performed over wired and/or wireless networks, such as network 108, to send and receive data, such as for Web-based requests, receiving server responses to requests and/or performing other tasks. Non-limiting and non-exhausting examples of such client devices 106 include personal computers (e.g., desktops, laptops), tablets, smart televisions, video game devices, mobile and/or smart phones and the like. In an example, client devices 106 can run one or more Web browsers that provide an interface for operators, such as human users, to interact with for making requests for resources to different web server-based applications and/or Web pages via the network 108, although other server resources may be requested by client devices.
The servers 102 comprise one or more server network devices or machines capable of operating one or more Web-based and/or non Web-based applications that may be accessed by other network devices (e.g. client devices, network traffic management devices) in the environment 100. The servers 102 can provide web objects and other data representing requested resources, such as particular Web page(s), image(s) of physical objects, JavaScript and any other objects, that are responsive to the client devices' requests. It should be noted that the servers 102 may perform other tasks and provide other types of resources. It should be noted that while only two servers 102 are shown in the environment 100 depicted in FIG. 1B, other numbers and types of servers may be utilized in the environment 100. It is contemplated that one or more of the servers 102 may comprise a cluster of servers managed by one or more network traffic management devices 110. In one or more aspects, the servers 102 may be configured implement to execute any version of Microsoft® IIS server, RADIUS server, DIAMETER server and/or Apache® server, although other types of servers may be used.
Network 108 comprises a publicly accessible network, such as the Internet, which is connected to the servers 102, client devices 106, and network traffic management devices 110. However, it is contemplated that the network 108 may comprise other types of private and public networks that include other devices. Communications, such as requests from clients 106 and responses from servers 102, take place over the network 108 according to standard network protocols, such as the HTTP, UDP and/or TCP/IP protocols, as well as other protocols. As per TCP/IP protocols, requests from the requesting client devices 106 may be sent as one or more streams of data packets over network 108 to the network traffic management device 110 and/or the servers 102. Such protocols can be utilized by the client devices 106, network traffic management device 110 and the servers 102 to establish connections, send and receive data for existing connections, and the like.
Further, it should be appreciated that network 108 may include local area networks (LANs), wide area networks (WANs), direct connections and any combination thereof, as well as other types and numbers of network types. On an interconnected set of LANs or other networks, including those based on differing architectures and protocols. Network devices such as client devices, 106, servers 102, network traffic management devices 110, routers, switches, hubs, gateways, bridges, cell towers and other intermediate network devices may act within and between LANs and other networks to enable messages and other data to be sent between network devices. Also, communication links within and between LANs and other networks typically include twisted wire pair (e.g., Ethernet), coaxial cable, analog telephone lines, full or fractional dedicated digital lines including T1, T2, T3, and T4, Integrated Services Digital Networks (ISDNs), Digital Subscriber Lines (DSLs), wireless links including satellite links and other communications links known to those skilled in the relevant arts. Thus, the network 108 is configured to handle any communication method by which data may travel between network devices.
LAN 104 comprises a private local area network that allows communications between the one or more network traffic management devices 110 and one or more servers 102 in the secured network. It is contemplated, however, that the LAN 104 may comprise other types of private and public networks with other devices. Networks, including local area networks, besides being understood by those skilled in the relevant arts, have already been generally described above in connection with network 108 and thus will not be described further.
As shown in the example environment 100 depicted in FIG. 1B, the one or more network traffic management devices 110 is interposed between client devices 106 with which it communicates with via network 108 and servers 102 with which it communicates with via LAN 104. In particular to the present disclosure, the network traffic management device 110 operates in conjunction with a clustered multi-processing (CMP) system which includes one or more network traffic management devices 110, each of which having one or more cores or processors 200 (FIG. 2A). Generally, the network traffic management device 110 manages network communications, which may include one or more client requests and server responses, via the network 108 between the client devices 106 and one or more of the servers 102. In any case, the network traffic management device 110 may manage the network communications by performing several network traffic related functions involving the communications. Some functions include, but are not limited to, load balancing, access control, and validating HTTP requests using JavaScript code that are sent back to requesting client devices 106.
FIG. 2A is a block diagram of the network traffic management device in accordance with an aspect of the present disclosure. As shown in FIG. 2A, the example network traffic management device 110 includes one or more device processors or cores 200, one or more device I/O interfaces 202, one or more network interfaces 204, and one or more device memories 206, which are coupled together by one or more bus 208. It should be noted that the network traffic management device 110 can be configured to include other types and/or numbers of components and is thus not limited to the configuration shown in FIG. 2A.
Device processor 200 of the network traffic management device 110 comprises one or more microprocessors configured to execute computer/machine readable and executable instructions stored in the device memory 206. Such instructions, when executed by one or more processors 200, implement general and specific functions of the network traffic management device 110, including the inventive process described in more detail below. It is understood that the processor 200 may comprise other types and/or combinations of processors, such as digital signal processors, micro-controllers, application specific integrated circuits (“ASICs”), programmable logic devices (“PLDs”), field programmable logic devices (“FPLDs”), field programmable gate arrays (“FPGAs”), and the like. The processor 200 is programmed or configured according to the teachings as described and illustrated herein.
Device I/O interfaces 202 comprise one or more user input and output device interface mechanisms. The interface may include a computer keyboard, mouse, display device, and the corresponding physical ports and underlying supporting hardware and software to enable the network traffic management device 110 to communicate with other network devices in the environment 100. Such communications may include accepting user data input and providing user output, although other types and numbers of user input and output devices may be used. Additionally or alternatively, as will be described in connection with network interface 204 below, the network traffic management device 110 may communicate with the outside environment for certain types of operations (e.g. smart load balancing) via one or more network management ports.
Network interface 204 comprises one or more mechanisms that enable the network traffic management device 110 to engage in network communications over the LAN 104 and the network 108 using one or more of a number of protocols, such as TCP/IP, HTTP, UDP, RADIUS and DNS. However, it is contemplated that the network interface 204 may be constructed for use with other communication protocols and types of networks. Network interface 204 is sometimes referred to as a transceiver, transceiving device, or network interface card (NIC), which transmits and receives network data packets over one or more networks, such as the LAN 104 and the network 108. In an example, where the network traffic management device 110 includes more than one device processor 200 (or a processor 200 has more than one core), each processor 200 (and/or core) may use the same single network interface 204 or a plurality of network interfaces 204. Further, the network interface 204 may include one or more physical ports, such as Ethernet ports, to couple the network traffic management device 110 with other network devices, such as servers 102. Moreover, the interface 204 may include certain physical ports dedicated to receiving and/or transmitting certain types of network data, such as device management related data for configuring the network traffic management device 110 or client request/server response related data.
Bus 208 may comprise one or more internal device component communication buses, links, bridges and supporting components, such as bus controllers and/or arbiters. The bus 208 enables the various components of the network traffic management device 110, such as the processor 200, device I/O interfaces 202, network interface 204, and device memory 206, to communicate with one another. However, it is contemplated that the bus 208 may enable one or more components of the network traffic management device 110 to communicate with one or more components in other network devices as well. Example buses include HyperTransport, PCI, PCI Express, InfiniBand, USB, Firewire, Serial ATA (SATA), SCSI, IDE and AGP buses. However, it is contemplated that other types and numbers of buses may be used, whereby the particular types and arrangement of buses will depend on the particular configuration of the network traffic management device 110.
Device memory 206 comprises computer readable media, namely computer readable or processor readable storage media, which are examples of machine-readable storage media. Computer readable storage/machine-readable storage media may include volatile, nonvolatile, removable, and non-removable media implemented in any method or technology for storage of information. Examples of computer readable storage media include RAM, BIOS, ROM, EEPROM, flash/firmware memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to store the information, which can be accessed by a computing or specially programmed network device, such as the network traffic management device 110.
Such storage media includes computer readable/processor-executable instructions, data structures, program modules, or other data, which may be obtained and/or executed by one or more processors, such as device processor 200. Such instructions, when executed, allow or cause the processor 200 to perform actions, including performing the inventive processes described below. The memory 206 may contain other instructions relating to the implementation and operation of an operating system for controlling the general operation and other tasks performed by the network traffic management device 110.
FIG. 2B illustrates a block diagram of the network interface in accordance with an aspect of the present disclosure. In particular, FIG. 2B shows the DMA processes used by network interface 204 for using multiple independent DMA channels with corresponding multiple applications, where each application has its own driver, and for sending packets.
As illustrated in FIG. 2B, the host system 111 can send a network data packet stored in host memory 212 to the network 108 via network interface controller 204 and Ethernet port 236. A send DMA operation is performed when the host system 111 uses a DMA channel to move a block of data from host memory 22 to a network interface controller peripheral (not shown) via network 108. To perform a send DMA operation, the host processor 200 places the target network data packet into DMA packet buffer 216 and creates a DMA send descriptor (not shown separately) in send DMA descriptor rings 218. The DMA send descriptor is jointly managed by the host system 111 and the network interface controller 204. The DMA send descriptor includes an address field and length field. The address field points to the start of the target network data packet in DMA packet buffer 216. The length field declares how many bytes of target data are present in the DMA packet buffer 216. The DMA send descriptor also has a set of bit flags (not shown) used to signal additional target data control and status information.
By way of example only, return DMA descriptor rings and send DMA descriptor rings 218 can be physically in the same hardware memory blocks functioning as return and send DMA rings, respectively, at different times. Alternatively, separate and distinct memory blocks within host memory 212 DMA memory resources 214 may be reserved for each return DMA descriptor rings and send DMA descriptor rings 218.
Host system 111 places the send descriptor on the send DMA descriptor rings 218 in host system memory 212. The host processor 200 determines the QoS of the network packet to be transferred to the network 108 and moves the network packet to the appropriate DMA packet buffer 216 and places the descriptor on the appropriate descriptor rings 1-4 in send DMA descriptor rings 218. The descriptor ring in send DMA descriptor rings 218 is chosen by the host system 111 which selects the DMA channel, its associated peripheral, and the QoS level within the DMA channel. Send descriptors created by host system 111 in send DMA descriptor rings 218 can be of variable types, where each descriptor type can have a different format and size. The send DMA descriptor rings 218 are capable of holding descriptors of variable type.
The host processor 200 writes one or more mailbox registers 230 of the network interface controller 204 to notify the network interface controller 204 that the packet is ready. In performing this notification, the host processor 200 performs a write operation to a memory mapped network interface controller register (mailbox register 230). The host processor 200 can report the addition of multiple descriptors onto the send DMA ring in a single update, or alternatively, in multiple updates.
The appropriate packet DMA engine within DMA engine 224 is notified that the packet is ready. The packet DMA engine 224 can be selected from available DMA channels, or if a specific application has a dedicated DMA channel, the associated packet DMA engine 224 for that channel is used. The DMA engine 224 retrieves the DMA descriptor from the send DMA descriptor rings 218. When multiple descriptors are outstanding in the send DMA descriptor rings 218, the DMA Engine 224 may retrieve more than one descriptor. Retrieving multiple descriptors at a time maximizes bus bandwidth and hardware efficiency. The DMA engine 224 is capable of receiving and processing send descriptors of variable type, format, and size.
As outlined above, the packet DMA engine 224 monitors the progress of the host DMA operations via a set of mailbox registers 230. Each packet DMA engine 224 supports its own set of mailbox registers 230. The mailbox registers 230 reside in a mapped address space of the network interface controller 204. When appropriate, the host processor 200 accesses the mailbox registers 230 by performing memory mapped read and write transactions to the appropriate target address. The mailbox registers 230 also contain ring status information for the Ring to QoS Mapper 228. In this send DMA example, the packet DMA engine 224 reads the send descriptor, performs the DMA operation defined by it, and reports to the host system 111 that the DMA operation is complete. During the DMA operation, data is received from one or more CPU Bus read transactions (e.g., HyperTransport or PCI Express read transactions).
DMA scheduler 226 chooses packets out of packet buffers 216 based upon the priority of the queued network data packets and schedules the transfer to the appropriate packet DMA engine 224. For clarity and brevity, only a single packet buffer, a single DMA scheduler, and DMA engine are shown in FIG. 2B, but it should be understood that additional packet buffers, DMA schedulers, and DMA engines supporting the independent DMA channels 1-n and associated applications App(1)-App(n) can be included in network interface controller 204.
The packet buffers 216 are selected based on the novel scheme (discussed below) using DMA scheduler 226. The DMA scheduler 226 selects which descriptor ring 1-4 out of return DMA descriptor rings (also referred to as return DMA rings, or send rings) within DMA memory resources 212 to service and the matching packet buffer 216 is accessed for a single packet. The scheduling process is then repeated for the next packet.
Each network packet retrieved from a packet buffer 216 is routed to the appropriate DMA channel controlled by the respective packet DMA engine such as the packet DMA engine 224. The DMA channel segments the network packet for delivery to host memory 212 via several, smaller, HyperTransport packets. These HyperTransport packets are interleaved with HyperTransport packets from the other DMA channels in the network interface controller 204.
Ring to QoS Mapper 228 examines the assigned send DMA ring in send DMA descriptor rings 218 and receives packet data and packet control information from the packet DMA engine 224. Using the control information, the Ring to QoS Mapper 228 stamps the appropriate QoS onto the network data packet, thereby allowing host system 111 to send the network data packet back to the network 108. For example, using the control information, the Ring to QoS Mapper 228 can create and prepend a HiGig header to the packet data.
An egress DMA routing interface 232 arbitrates access to the network for DMA send packets. When a Ring to QoS Mapper 228 has a network packet ready to send, the egress DMA routing interface 232 arbitrates its access to the Ethernet port 236 and routes the packet to the correct interface if there is more than one present in the network interface controller 204. The egress DMA routing interface 232 behaves like a crossbar switch and monitors its attached interfaces for available packets. When a packet becomes available, the egress DMA routing interface 232 reads the packet from the selected ring to QoS mapper 228 and writes it to the destination interface. The egress DMA routing interface 232 moves complete packets to Ethernet MACs 234. When multiple sources are contending for egress DMA routing interface 232, the egress DMA routing interface 232 uses a weighted arbitration scheme as discussed in more detail below.
The network interface controller 204 provides DMA services to a host complex such as the host system 111 on behalf of its attached I/O devices such as the Ethernet port 236. DMA operations involve the movement of data between the host memory 212 and the network interface controller 204. The network interface controller 204 creates and manages HyperTransport or other types of CPU Bus read/write transactions targeting host memory 22. Data transfer sizes supported by DMA channels maintained by various components of application delivery controller 110 are much larger than the maximum HyperTransport or CPU bus transaction size. The network interface controller 204 segments single DMA operations into multiple smaller CPU Bus or HyperTransport transactions. Additionally, the network interface controller 204 creates additional CPU bus or HyperTransport transactions to support the transfer of data structures between the network interface controller 204 and host memory 212.
FIG. 2C illustrates further details of the network traffic management device in accordance with an aspect of the present disclosure. In particular, the network traffic management device 110 is shown handling a plurality of independent applications App(1)-App(n) being executed by one or more processors (e.g., host processor 200) in host system 111. Each application in the plurality of applications App(1)-App(n) has its own respective application driver shown as Driver 1, Driver 2, . . . , Driver ‘n’ associated with the respective application, where the index n denotes an unlimited number of executing applications and drivers. Applications App(1)-App(n) send and receive data packets from and to the network 108 (and/or LAN 104), respectively, using respective DMA channels (e.g., DMA channels 1-n). DMA channels 1-n are uniquely assigned to individual applications out of App(1)-App(n). In this example, drivers 1-n manage access to respective DMA channels 1-n and do not require knowledge of each other or a common management database or entity (e.g., a hypervisor). By way of example only, each of applications App(1)-App(n) can be independent instances of different applications, or alternatively, may be independent instances of the same application, or further, may be different operating systems supported by different processors in host system 111 (e.g., host processor 200).
DMA channels 1-n each have unique independent resources allotted to them, for example, a unique PCI bus identity including a configuration space and base address registers, an independent view of host system memory 212, a unique set of DMA descriptor ring buffers, a unique set of packet buffers 216, unique DMA request/completion signaling (through interrupts or polled memory structures), and other resources. Each of DMA channels 1-n is unique and independent thereby permitting management by separate unique drivers 1-n.
The network interface controller 204 classifies received packets to determine destination application selected from applications App(1)-App(n) and thereby selects the matching DMA channel to deliver the packet to the corresponding application. By way of example only, packet classification includes reading packet header fields thereby permitting application identification. Further by way of example only, packet classification includes hash calculation for distribution of packets across multiple instances of the same application, and/or reading a cookie stored, for example, in the network interface controller 204 associated with the application and the received network packet.
In general, the present disclosure utilizes hardware and software in the network traffic management device when pacing network traffic being sent to another network device (e.g. client, server). The purpose is for the network traffic management device to pace delivery of session data to the client to match the rate at which the client consumes the data, which adds value for mobile clients and networks. The network traffic management device utilizes a transmit time calendar having a plurality of quanta of transmit times. For example, one quanta may be 1 microsecond, although other time durations are contemplated.
FIG. 3 illustrates an example transmit ring or bucket in accordance with an aspect of the present disclosure. As shown in FIG. 3, the bucket 300 is a software based data construct which holds a plurality of data packet DMA descriptors which point to the pending transmit packets and has packets from a plurality of various, different sessions. The bucket 300 has a fence 302 which marks the last descriptor in the bucket. Software determines what data packets to send and when to send those data packets. The software communicates with the hardware component wherein the software enhances the data structures to communicate a time component with regard to when the selected data packets are to be sent. In particular, the software component divides session data into multiple maximum segment sized (MSS) or smaller sized packets. The software component distributes the packets in buckets separated by fixed transmit times, wherein the buckets are then handed off to the hardware component, such as a DMA ring, to handle the delivery of the data packets populated in the buckets, by processing the buckets themselves.
FIG. 4 illustrates a time line of an example transmit ring or bucket in accordance with an aspect of the present disclosure. As can be seen in FIG. 4, the transmit time calendar utilizes a plurality of buckets 300 where session data 400, such as data packet DMA descriptors is populated into the buckets 300. Each bucket has a predetermined size and adjacent buckets are separate by a transmit time or quanta that is fixed (shown as T1-T4). It should be noted the time calendar is configured to have a finite number of buckets, wherein the calendar effectively wraps around to the first bucket after the last bucket has been handled. In addition, multiple packet descriptors can be placed in the same bucket to increase bandwidth. The software component may decide whether to pace a data packet, as opposed to being bulk data (FIG. 5) based on size, type of traffic the data packet is associated with, QoS parameters (based on flow) and the like.
In an aspect, one or more buckets 300 can be skipped for distribution, by the software component, to increase intra-packet spacing. One way for determining how many buckets to skip before placing a data packet descriptor in a bucket 300 can be based on the type or class of application in which the data is delivered (e.g. video streaming). For example, video streaming applications would benefit from a constant rate of data delivery. Another way of determining (based on speed) would be using TCP congestion control algorithms which calculate how many packets are to be sent over time. The software does not have to hunt for holes where packet descriptors can be inserted. Instead, the software component need only to drop packet descriptors into the one or more buckets 300.
Once a bucket 300 is populated by the software component, the software component releases the bucket to the hardware component, such as the network interface 204. In particular, the bucket contents are written into the network interface's 204 DMA ring 218 en-mass. In an aspect, the hardware component can determine whether the size of a particular data packet in a bucket is of a threshold size such that the data packet can be processed within the allotted time quanta.
A gross timer is applied by the hardware component in writing the packets into the DMA ring 218, wherein the poll loop time of the processor 200 of the network traffic management device 110 is used as the gross timer. The sum of released bucket time quanta's must excel poll loop time.
The fence 304 marking at the end of a particular bucket 300 serves as a timing boundary at the end of the bucket to allow the hardware component to do precise bucket to bucket timing.
FIG. 5 illustrates a block diagram of hardware based time enforcement in performed by a high speed bridge (HSB) priority mechanism in accordance with an aspect of the present disclosure. As shown in FIG. 5, data packets that are written to buckets that are released to the hardware are received in a pacing send ring 500. In contrast, non-paced data (data not written to buckets) are received in a bulk send ring 502.
In an aspect, the pacing send ring 500 is given higher priority in terms of being sent to the ring arbitrator 506. Thus, the bulk traffic in the bulk send ringer 502 advances to the arbitrator 506 when the paced traffic (from the pacing send ring 500) is blocked or is absent. A pacing timer 504 in coupled to the pacing send ring 500 and the arbitrator 506, wherein the pacing timer is reset at the start of a new bucket 300. The pacing timer 504 also blocks traffic at bucket boundaries until the bucket quanta time expires.
FIG. 6 illustrates an example transmit time line in accordance with an aspect of the present disclosure. As shown in the time line 600, the hardware component consumes the data packets in the first bucket 602 for the entire time quanta which ends at boundary A. In the second bucket 604, it is shown that the hardware component finishes writing the paced data packets such that additional time remains for the allotted time. The hardware component thereafter processes bulk data for the remaining amount of time in the time quanta until reaching boundary B. The same occurs in bucket 606. In bucket 608, there is a period of time where no data is written, which can result in no bulk data or paced data being available for writing to the DMA engine.
FIG. 7 illustrates a flow chart of the software implementation of populating buckets with data packet descriptors in accordance with an aspect of the present disclosure. As shown in FIG. 7, the process 700 occurs when a first bucket of a plurality of buckets is selected by the application module 210 of the network traffic management device (Block 702). The application module 210 thereafter populates the first bucket with one or more data packet descriptors associated with data packets to be released to the network interface 204 (Block 704). The application module 210 thereafter determines whether there are additional paced or bulk data packets that can be added to the current selected bucket (Block 706). If so, the process repeats back to Block 704. If not, the process proceeds to Block 708.
Once the application module 210 has populated the bucket with the last data packet, the application module 210 applies a fence which represents the last data packet for that bucket (Block 708). The application module 210 thereafter determines if the selected bucket is the last bucket in the time calendar (Block 710). If so, the application module 210 effectively wraps around the time calendar and selects the first bucket (Block 702). If not, the application module 210 selects the next bucket in the time calendar (Block 712), wherein the process proceeds back to Block 704.
FIG. 8 illustrates a flow chart of the software implementation of populating buckets with data packet descriptors in accordance with an aspect of the present disclosure. As shown in FIG. 8, the process 800 occurs when a first bucket of a plurality of buckets is selected by the network interface 204 of the network traffic management device (Block 802). The network interface 204 thereafter processes paced data packet(s) for the selected bucket (Block 804). The network interface 204 thereafter determines whether additional time is available for the selected bucket (Block 806). If so, the network interface 204 determines if bulk data packets are present in the bucket (Block 808). If so, the network interface 204 processes the bulk data for the bucket (Block 810). The process then repeats back to Block 806.
If no additional allotted time is left, the network interface 204 selects the next bucket 812 and the process proceeds back to Block 804. Referring back to Block 808, if no bulk data is available for processing for a particular bucket, the network interface 204 does not write any data packets and allows the remaining time for the bucket quanta to expire (Block 814). The process then proceeds to Block 812.
Having thus described the basic concepts, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the examples. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefore, is not intended to limit the claimed system and/or processes to any order except as may be specified in the claims. Accordingly, the system and method is limited only by the following claims and equivalents thereto.

## Claims

1. A method for transmitting data packets at an optimized rate, the method comprising:
populating, by the network traffic management computing device, a plurality of buckets with one or more selected data packet descriptors associated with one or more corresponding ones of a subset of a plurality of data packets to be transmitted as paced and another subset of the data packets to be transmitted as bulk;
releasing, by the network traffic management computing device, one of the buckets to a hardware component comprising a pacing send ring and a bulk send ring, the releasing comprising writing one or more of the subset of the data packets to the pacing send ring and one or more of the another subset of the data packets to the bulk send ring; and
transmitting, by the network traffic management computing device, the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring for a predetermined transmit time, wherein the subset of the data packets are strictly prioritized over the another subset of the data packets and the one or more of the another subset of the data packets are only transmitted within the predetermined transmit time when the pacing send ring is emptied during the predetermined transmit time.

2. The method as set forth in claim 1, further comprising repeating, by the network traffic management computing device, the releasing and transmitting for each other of the buckets.

3. The method as set forth in claim 1, wherein the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring are transmitted by a direct memory access (DMA) transmit engine.

4. The method as set forth in claim 1, wherein the subset of the data packets to be transmitted is identified as paced and the another subset of the data packets is identified as bulk based on a data packet size, an associated type of traffic, or a quality of service (QoS) parameter.

5. The method as set forth in claim 1, further comprising:
determining, by the network traffic management computing device, when another one of the buckets should be skipped based on a type of application from which the ones of the data packets associated with the selected data packet descriptors populated therein originated; and
skipping, by the network traffic management computing device, the another one of the buckets such that the releasing and transmitting are not repeated for the another one of the buckets, when the determining indicates that the another one of the buckets should be skipped.

6. The method as set forth in claim 1, further comprising waiting, by the network traffic management computing device, to release another one of the buckets when the one or more of the subset of the data packets are transmitted from the pacing send ring and the one or more of the another subset of the data packets are transmitted from the bulk send ring prior to the expiration of the predetermined transmit time.

7. A non-transitory computer readable medium having stored thereon instructions for transmitting data packets at an optimized rate, comprising executable code which when executed by at least one processor and/or network interface causes the processor and/or network interface to perform steps comprising:
populating a plurality of buckets with one or more selected data packet descriptors associated with one or more corresponding ones of a subset of a plurality of data packets to be transmitted as paced and another subset of the data packets to be transmitted as bulk;
releasing one of the buckets to a hardware component comprising a pacing send ring and a bulk send ring, the releasing comprising writing one or more of the subset of the data packets to the pacing send ring and one or more of the another subset of the data packets to the bulk send ring; and
transmitting the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring for a predetermined transmit time, wherein the subset of the data packets are strictly prioritized over the another subset of the data packets and the one or more of the another subset of the data packets are only transmitted within the predetermined transmit time when the pacing send ring is emptied during the predetermined transmit time.

8. The non-transitory computer readable medium as set forth in claim 7, wherein the executable code when executed by the processor and/or the network interface further causes the processor and/or the network interface to perform at least one additional step comprising repeating the releasing and transmitting for each other of the buckets.

9. The non-transitory computer readable medium as set forth in claim 7, wherein the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring are transmitted by a direct memory access (DMA) transmit engine.

10. The non-transitory computer readable medium as set forth in claim 7, wherein the subset of the data packets to be transmitted is identified as paced and the another subset of the data packets is identified as bulk based on a data packet size, an associated type of traffic, or a quality of service (QoS) parameter.

11. The non-transitory computer readable medium as set forth in claim 7, wherein the executable code when executed by the processor and/or the network interface further causes the processor and/or the network interface to perform at least one additional step comprising:
determining when another one of the buckets should be skipped based on a type of application from which the ones of the data packets associated with the selected data packet descriptors populated therein originated; and
skipping the another one of the buckets such that the releasing and transmitting are not repeated for the another one of the buckets, when the determining indicates that the another one of the buckets should be skipped.

12. The non-transitory computer readable medium as set forth in claim 7, wherein the executable code when executed by the processor and/or the network interface further causes the processor and/or the network interface to perform at least one additional step comprising waiting to release another one of the buckets when the one or more of the subset of the data packets are transmitted from the pacing send ring and the one or more of the another subset of the data packets are transmitted from the bulk send ring prior to the expiration of the predetermined transmit time.

13. A network traffic management computing device comprising at least one processor and/or network interface and a memory coupled to the processor and/or network interface which is configured to be capable of executing programmed instructions comprising and stored in the memory to:
populate a plurality of buckets with one or more selected data packet descriptors associated with one or more corresponding ones of a subset of a plurality of data packets to be transmitted as paced and another subset of the data packets to be transmitted as bulk;
release one of the buckets to a hardware component comprising a pacing send ring and a bulk send ring, the releasing comprising writing one or more of the subset of the data packets to the pacing send ring and one or more of the another subset of the data packets to the bulk send ring; and
transmit the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring for a predetermined transmit time, wherein the subset of the data packets are strictly prioritized over the another subset of the data packets and the one or more of the another subset of the data packets are only transmitted within the predetermined transmit time when the pacing send ring is emptied during the predetermined transmit time.

14. The network traffic management computing device as set forth in claim 13, wherein the processor and/or network interface coupled to the memory is further configured to be capable of executing at least one additional programmed instruction comprising and stored in the memory to repeat the releasing and transmitting for each other of the buckets.

15. The network traffic management computing device as set forth in claim 13, wherein the one or more of the subset of the data packets from the pacing send ring and the one or more of the another subset of the data packets from the bulk send ring are transmitted by a direct memory access (DMA) transmit engine.

16. The network traffic management computing device as set forth in claim 13, wherein the subset of the data packets to be transmitted is identified as paced and the another subset of the data packets is identified as bulk based on a data packet size, an associated type of traffic, or a quality of service (QoS) parameter.

17. The network traffic management computing device as set forth in claim 13, wherein the processor and/or network interface coupled to the memory is further configured to be capable of executing at least one additional programmed instruction comprising and stored in the memory to:
determine when another one of the buckets should be skipped based on a type of application from which the ones of the data packets associated with the selected data packet descriptors populated therein originated; and
skip the another one of the buckets such that the releasing and transmitting are not repeated for the another one of the buckets, when the determining indicates that the another one of the buckets should be skipped.

18. The network traffic management computing device as set forth in claim 13, wherein the processor and/or network interface coupled to the memory is further configured to be capable of executing at least one additional programmed instruction comprising and stored in the memory to wait to release another one of the buckets when the one or more of the subset of the data packets are transmitted from the pacing send ring and the one or more of the another subset of the data packets are transmitted from the bulk send ring prior to the expiration of the predetermined transmit time.