Patent Publication Number: US-8996764-B1

Title: Method and apparatus for controlling transmission of data packets from and to a server

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation of and claims priority to U.S. patent application Ser. No. 13/867,714, filed Apr. 22, 2013, now U.S. Pat. No. 8,738,825, issued May 27, 2014, which is a continuation of and claims priority to U.S. patent application Ser. No. 12/831,835, filed Jul. 7, 2010, now U.S. Pat. No. 8,429,316, issued Apr. 23, 2013, which claims priority to U.S. Provisional Patent Application No. 61/230,632, filed Jul. 31, 2009, which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     Embodiments of the present invention relate to a blade server system in general, and more specifically, to a low power state of a switch in a blade server system. 
     BACKGROUND 
     The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure. 
     A high density blade server system typically includes a plurality of server modules (hereinafter also referred to as server blades). By arranging the plurality of server blades in a multi-server cabinet, the high density blade server system achieves significant cost and space savings over a plurality of conventional stand-alone servers. These savings result directly from the sharing of common resources, e.g., common power supplies, common cooling systems, enclosures, etc., and the reduction of space required by this type of multi-server system, while providing a significant increase in available computing power. A blade server system usually includes one or more switches configured to route data packets in the blade server system. 
     A modern centralized data processing center generally has several (e.g., numbering even in the hundreds) such blade server systems. Power consumption per unit of computing power decreases with a blade server system compared to, for example, a system that comprises a plurality of conventional stand alone servers. However, the larger number of server blades within a blade server system, and the large number of such blade server systems in a data processing center results in significant power consumption. Thus, a marketability of a blade server system is at least in part tied to a power usage by the blade server system. 
     SUMMARY 
     In various embodiments, the present disclosure provides a method comprising categorizing each data packet of a plurality of data packets into one of at least two priority groups of data packets; and controlling transmission of data packets of a first priority group of data packets during a first off-time period such that during the first off-time period, data packets of the first priority group of data packets are prevented from being transmitted to a switching module from one or more server blades. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following detailed description, reference is made to the accompanying drawings wherein like numerals designate like parts throughout. 
         FIG. 1  schematically illustrates a blade server system. 
         FIG. 2   a  illustrates a timing curve for controlling transmission of data packets from a plurality of server blades to a switching module of  FIG. 1 . 
         FIG. 2   b  illustrates a first timing curve and a second timing curve for controlling transmission of (i) data packets included in a regular priority group of data packets, and (ii) data packets included in a high priority group of data packets, respectively, from the plurality of server blades to the switching module of  FIG. 1 . 
         FIG. 3  illustrates a method for operating the blade server system of  FIG. 1 . 
         FIG. 4  is a block diagram of a system suitable for practicing embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Various operations may be described as multiple discrete operations in turn, in a manner that may be helpful in understanding embodiments of the present invention; however, the order of description should not be construed to imply that these operations are order dependent. 
     The description may use the phrases “in an embodiment,” or “in embodiments,” which may each refer to one or more of the same or different embodiments. The phrase “in some embodiments” is used repeatedly. The phrase generally does not refer to the same embodiments; however, it may. The terms “comprising,” “having,” and “including” are synonymous, unless the context dictates otherwise. The phrase “A and/or B” means (A), (B), or (A and B). The phrase “A/B” means (A), (B), or (A and B), similar to the phrase “A and/or B.” The phrase “at least one of A, B and C” means (A), (B), (C), (A and B), (A and C), (B and C) or (A, B and C). The phrase “(A) B” means (B) or (A and B), that is, A is optional. 
       FIG. 1  schematically illustrates a blade server system  10 , in accordance with various embodiments of the present disclosure. The blade server system  10  includes a plurality of server blades  20   a , . . . ,  20 N. Although not illustrated in  FIG. 1 , individual server blades of the plurality of server blades  20   a , . . . ,  20 N include one or more processors, memory, a host bus adaptor, an input/output port, and/or the like. 
     The blade server system  10  also includes a switching module  14  that is communicatively coupled to each of the plurality of server blades  20   a , . . . ,  20 N through appropriate communication links. Although only one switching module  14  is illustrated in  FIG. 1 , in various other embodiments, the blade server system  10  may include more than one switching module. 
     The switching module  14  receives data packets from one or more of the server blades  20   a , . . . ,  20 N and/or from one or more components that are external to the blade server system  10 . The switching module  14  selectively routes the received data packets to an appropriate destination (e.g., to one or more of the server blades  20   a , . . . ,  20 N and/or to one or more components that are external to the blade server system  10 ). Thus, the switching module  14  facilitates transmission of data packets (i) between individual server blades of the plurality of server blades  20   a , . . . ,  20 N, and/or (ii) between a server blade of the plurality of server blades  20   a , . . . ,  20 N and a component external to the blade server system  10 . In various embodiments, data packets include data bits associated with user data, control data, and/or the like. 
     The switching module  14  includes several components, only some of which is illustrated in  FIG. 1 . For example, switching module  14  includes a buffer  30  and a memory  34 . In various embodiments, the buffer  30  is divided in two (or more) sections, illustrated as buffer  30   a  and buffer  30   b  in  FIG. 1 . The memory  34  may be any suitable volatile memory (e.g., a dynamic random access memory) or non-volatile memory. 
     The switching module  14  also includes a forwarding table  38  configured to store routing information associated with the data packets received by the switching module  14 . Although illustrated as a separate component, in various embodiments, the forwarding table  38  is stored in the memory  34 . 
     The blade server system  10  also includes a packet flow control module  18 , which is communicatively coupled to the switching module  14  and to the server blades  20   a , . . . ,  20 N. The packet flow control module  18  is communicatively coupled to the switching module  14  and to the server blades  20   a , . . . ,  20 N using, for example, appropriate communication links, one or more device drivers, and/or appropriate application program interfaces (APIs). Although illustrated as a separate component in  FIG. 1 , in various other embodiments, the packet flow control module  18  may be included in the switching module  14  and/or in one of the blade servers  20   a , . . . ,  20 N. 
     Although not illustrated in  FIG. 1 , the blade server system  10  also includes several other components. For example, although not illustrated in  FIG. 1 , the blade server system  10  includes one or more power supply modules configured to supply power to various components of the blade server system  10 , one or more cooling modules configured to provide cooling to various components of the blade server system  10 , and/or the like. 
     In various embodiments, the packet flow control module  18  controls an ingress or transmission of data packets from the server blades  20   a , . . . ,  20 N to the switching module  14 .  FIG. 2   a  illustrates a timing curve  200   a  for controlling transmission of data packets from the server blades  20   a , . . . ,  20 N to the switching module  14  of  FIG. 1 , in accordance with various embodiments of the present disclosure. In various embodiments, control signals corresponding to the timing curve  200   a  is generated by the packet flow control module  18 , and is received by one or more server blades  20   a , . . . ,  20 N and/or the switching module  14  of  FIG. 1 . Referring to  FIGS. 1 and 2 , during an on-time period a1, the packet flow control module  18  allows flow of data packets from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . On the other hand, during an off-time period b1, the packet flow control module  18  prevents flow of data packets from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . 
     The on-time period a1 and off-time period b1 form a timing pattern A1. In various embodiments, the timing pattern A1 is repeated a number of times, as illustrated in  FIG. 2   a . That is, each timing pattern A1 includes an on-time period a1 and an off-time period b1. Thus, an on-time period a1 is followed by an off-time period b1, which is followed again by another on-time period a1, and so on. 
     For the purpose of this disclosure and unless otherwise disclosed, an on-time period a1 and an off-time period b1 may refer to any one of the plurality of on-time periods a1 and any one of the plurality of off-time periods b1, respectively, as illustrated in  FIG. 2   a . For the purpose of this disclosure and unless otherwise disclosed, on-time periods a1 may refer to more than one on-time period a1 (e.g., all the on-time periods a1 illustrated in  FIG. 2   a ). For the purpose of this disclosure and unless otherwise disclosed, off-time periods b1 may refer to more than one off-time period b1 (e.g., all the off-time periods b1 illustrated in  FIG. 2   a ). For the purpose of this disclosure and unless otherwise disclosed, a timing pattern A1 may refer to any one of the plurality of timing patterns A1 illustrated in  FIG. 2   a . For the purpose of this disclosure and unless otherwise disclosed, timing patterns A1 may refer to more than one timing pattern A1 (e.g., all the timing patterns A1 illustrated in  FIG. 2   a ). 
     Referring again to  FIGS. 1 and 2   a , a server blade (e.g., server blade  20   a ) transmits a data packet to the switching module  14  during an on-time period a1. However, if the server blade  20   a  desires to transmit another data packet to the switching module  14  during an off-time period b1, transmission of the another data packet from the server blade  20   a  to the switching module  14  is paused until a start of a next on-time period a1. 
     In various embodiments, controlling of the data packets (e.g., selectively pausing a data packet from transmission from the server blade  20   a  to the switching module  14  during off-time periods b1), by the packet flow control module  18 , may be in compliance with or performed using, for example, any appropriate flow control protocol. For example, an appropriate Ethernet pause flow control protocol (e.g., Institute of Electrical and Electronics Engineers (IEEE) 802.3x standard, approved in 1997), an appropriate priority-based flow control protocol (e.g., IEEE 802.1qbb, which is presently at drafting stage), and/or any other appropriate flow control protocol is used to control the data packets. 
     During the off-time periods b1, the switching module  14  operates in a low power state. In various embodiments, while the switching module  14  is in the low power state, one or more components of the switching module  14  operate in a low power mode, a deep power down mode, and/or may be switched off. For example, while the switching module  14  is in the low power state (e.g., during the off-time periods b1), the buffer  30  and/or the memory  34  operate in the low power mode and/or the deep power down mode. In another example, dynamic power to one or more components of the switching module  14  is reduced during the low power state of the switching module  14 . In yet another example, static power to one or more other components of the switching module  14  is switched off during the low power state of the switching module  14 . As the switching module  14  does not receive any data packets during the off-time periods b1 (i.e., during the low power state), operating, by the switching module  14 , in the low power state during the off-time periods b1 does not result in any loss of any data packets transmitted to the switching module  14 . 
     On the other hand, during the on-time periods a1, the switching module  14  operates at a regular power state. In various embodiments, while the switching module  14  is in the regular power state, one or more components (e.g., buffer  30 , memory  34 , and/or the like) of the switching module  14  operate at a regular or normal power level. 
     Referring again to  FIG. 2   a , a duty cycle of the blade server system  10 , associated with the timing curve  200   a , refers to a ratio of (i) a duration of an on-time period a1, and (ii) a duration of a timing pattern A1. In various embodiments, the duty cycle may be expressed in percentage form. Thus, the duty cycle associated with the timing curve  200   a  is equal to (a1/A1)×100, i.e., equal to (a1/(a1+b1))×100. The duty cycle is a representation of a percentage of time the switching module  14  operates at the regular power state and routes data packets to appropriate destinations. 
     A load factor of the blade server system  10  may be, for example, associated with a number of data packets transmitted within the blade server system  10 . In various embodiments, the duty cycle of the switching mode  14  is varied based at least in part on, for example, the load factor of the blade server system  10 . In an example, the load factor of the blade server system  10  is high during day time, medium during the evenings, and low at night. Accordingly, for example, the duty cycle of the blade server system  10  is high (e.g., 70%) during day time, is medium (e.g., 40%) during the evenings, and is low (e.g., 10%) at night. 
     In various embodiments, the duty cycle is varied dynamically based at least in part on the load factor of the blade server system  10 . In an example, the current duty cycle of the blade server system  10  is about 50%. However, the current load factor the blade server system  10  is higher than a load factor that can be supported by the duty cycle of 50%. Accordingly, data packets may get accumulated in, for example, one or more queues included in corresponding one or more of the server blades  20   a , . . . ,  20 N. In the case where a number of data packets accumulated in one or more queues exceeds a threshold value, the packet flow control module  18  dynamically increases the duty cycle. Such an increase in the duty cycle allows the switching module  14  to operate in the regular power state for more time duration. This provides more time to the switching module  14  to handle and route data packets accumulated in the one or more queues, thereby decreasing the number of data packets accumulated in the one or more queues. 
     On the other hand, in the case where a number of data packets accumulated in one or more queues decreases below another threshold value, the duty cycle of the switching module  14  is decreased dynamically by the packet flow control module  18 , as will be readily understood by those skilled in the art based on the teachings of this disclosure. 
     Operating in the low power state, by the switching module  14 , has several advantages. For example, while in the low power state, one or more components of the switching module  14  operate in a low power mode, a deep power down mode, and/or are switched off, resulting in significant savings in power consumed by the switching module  14 , without adversely impacting a computing power or performance of the blade server system  10 . Due to relatively less power consumption, the blade server system  10  generates relatively less heat, resulting in reduced cooling requirements for the blade server system  10 . 
     In various embodiments, the packet flow control module  18  prioritizes data packets transmitted by the server blades  20   a , . . . ,  20 N to the switching module  14 . For example, the packet flow control module  18  categorizes each of the data packets in one of a plurality of priority groups based on an importance or criticality of the respective data packet. The packet flow control module  18  controls transmission of data packets from the server blades  20   a , . . . ,  20 N to the switching module based on an associated priority group of the data packets. 
     For example, the packet flow control module  18  prioritizes data packets, transmitted by the server blades  20   a , . . . ,  20 N to the switching module  14 , in a high priority group and a regular priority group. Data packets included in the high priority group has higher priority relative to the data packets included in the regular priority group. For the purpose of this disclosure and unless otherwise disclosed, a regular priority data packet refers to a data packet included in the regular priority group of data packets, and a high priority data packet refers to a data packet included in the high priority group of data packets. 
     Packet flow control module  18  categorizes the data packets in accordance with, for example, an appropriate priority-based flow control protocol (e.g., IEEE 802.1qbb and/or IEEE 802.1Q-2005, approved on 2005). For example, IEEE 802.1Q-2005 prioritizes different classes of traffic (voice, video, data, etc) in 7 different priority levels, with a priority level of 0 implying lowest priority and a priority level of 7 implying highest priority. In various embodiments, of the 7 priority levels defined in the IEEE 802.1Q-2005 protocol, data packets associated with priority levels 0-5 may be included in the regular priority group of data packets, and data packets associated with priority levels 6-7 may be included in the high priority group of data packets. However, such prioritization is purely an example, and in various other embodiments, any other number of priority groups, using any other appropriate priority-based flow control protocol (or any other appropriate protocol), may also be possible. 
       FIG. 2   b  illustrates timing curves  200   b  and  200   c  for controlling transmission of (i) data packets included in the regular priority group of data packets, and (ii) data packets included in the high priority group of data packets, respectively, from the server blades  20   a , . . . ,  20 N to the switching module  14 , in accordance with various embodiments of the present disclosure. 
     Referring to the timing curve  200   b  of  FIG. 2   b  and to  FIG. 1 , during an on-time period a2, the packet flow control module  18  allows flow of data packets, included in the regular priority group, from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . On the other hand, during an off-time period b2, the packet flow control module  18  prevents or pauses flow of data packets, included in the regular priority group, from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . 
     The on-time period a2 and off-time period b2 form a timing pattern A2. In various embodiments, the timing pattern A2 is repeated a number of times, as illustrated in  FIG. 2   b . That is, each timing pattern A2 includes an on-time period a2 and an off-time period b2. Thus, an on-time period a2 is followed by an off-time period b2, which is followed again by another on-time period a2, and so on. 
     For example, a sever blade (e.g., server blade  20   a ) transmits a regular priority data packet to the switching module  14  during the on-time period a2. However, if the server blade  20   a  desires to transmit another regular priority data packet to the switching module  14  during the off-time period b2, transmission of the another regular priority data packet from the server blade  20   a  to the switching module  14  is paused or delayed (e.g., using any appropriate flow control protocol, as previously disclosed) until a start of a next on-time period a2. 
     The timing curve  200   c  similarly illustrates controlling of data packets included in the high priority group of data packets (e.g., controlling of high priority data packets). For example, in the timing curve  200   c , during an on-time period a3, the packet flow control module  18  allows flow of data packets, included in the high priority group, from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . On the other hand, during an off-time period b3, the packet flow control module  18  prevents flow of data packets, included in the high priority group, from one or more of the server blades  20   a , . . . ,  20 N to the switching module  14 . 
     The on-time period a3 and off-time period b3 form a timing pattern A3. In various embodiments, the timing pattern A3 is repeated a number of times, as illustrated in  FIG. 2   b . That is, each timing pattern A3 includes an on-time period a3 and an off-time period b3. Thus, an on-time period a3 is followed by an off-time period b3, which is followed again by another on-time period a3, and so on. 
     For example, a sever blade (e.g., server blade  20   a ) transmits a high priority data packet to the switching module  14  during an on-time period a3. However, if the server blade  20   a  desires to transmit another high priority data packet to the switching module  14  during an off-time period b3, transmission of the another high priority data packet from the server blade  20   a  to the switching module  14  is paused or delayed (e.g., using any appropriate flow control protocol, as previously disclosed) until a start of a next on-time period a3. 
     The switching module  14  operates in a first level of low power state during the off-time periods b2, and operates in a second level of low power state during the off-time periods b3. One or more components of the switching module  14  operates in a low power mode, a deep power down mode, or are switched off during the first level of low power state and/or the second level of low power state. 
     As previously disclosed, the buffer  30  of the switching module  14  is segmented in buffer  30   a  and buffer  30   b . In various embodiments, the buffer  30   a  is configured to buffer data packets included in the regular priority group of data packets, and the buffer  30   b  is configured to buffer data packets included in the high priority group of data packets. Accordingly, during the first level of low power state of the switching module  14 , buffer  30   a  operates in the low power mode, the deep power down mode, or is switched off. On the other hand, during the second level of low power state of the switching module  14 , buffer  30   b  operates in the low power mode, the deep power down mode, or is switched off. If the first level of low power state and the second level of low power state of the switching module  14  coincide, both the buffer  30   a  and the buffer  30   b  operate in the low power mode, the deep power down mode, and/or are switched off. 
     In various embodiments, a number of regular priority data packets routed by the switching module  14  is higher than a number of high priority data packets routed by the switching module  14 . Accordingly, the buffer  30   a  is larger in size compared to the buffer  30   b.    
     If a buffer enters a deep power mode, the buffer may take relatively more time to exit the deep power mode (e.g., as compared to a time taken for exiting from a low power mode). Furthermore, if a buffer is switched off, data stored in the buffer may be lost while the buffer is switched on once again. 
     In various embodiments, the buffers  30   a  and/or  30   b  operate in the low power mode, the deep power down mode, or are switched off based at least in part of a number of data packets buffered in the buffers  30   a  and/or  30   b . In an example, in the case where the buffer  30   a  is empty before the switching module  14  enters the first level of low power state, the buffer  30   a  then operates in the deep power down mode or is switched off. In another example, in the case where the buffer  30   b  stores one or more data packets before the switching module  14  enters the second level of low power state, the buffer  30   b  then operates in the low power mode (e.g., instead of operating in the deep power down mode or being switched off) during the second level of low power state (e.g., so that the buffered one or more data packets are not lost, and the buffer  30   a  exits the low power mode relatively quickly). 
     Although not illustrated in  FIG. 1 , in various embodiments, the memory  34  may also be segmented into two sections of memory: a first section of memory associated with (e.g., configured to store) data packets included in the regular priority group of data packets, and a second section of memory associated with data packets included in the high priority group of data packets. In such a case, the first section of memory operates in the low power mode, the deep power down mode, or is switched off during the first level of low power state of the switching module  14 . On the other hand, the second section of memory operates in the low power mode, the deep power down mode, or is switched off during the second level of low power state of the switching module  14 . In the case where the first level of low power state and the second level of low power state of the switching module  14  coincide, both the sections of memory operate in the low power mode, the deep power down mode, and/or are switched off. 
     In various embodiments, if a number of regular priority data packets routed by the switching module  14  is higher than a number of high priority data packets routed by the switching module  14 , the first section of memory is relatively larger (e.g., has relatively larger storage space) than the second section of memory. 
     The switching module  14  operates in a first level of regular power state during the on-time periods a2, and operates in a second level of regular power state during the on-time periods a3. While the switching module  14  is in the first level of regular power state, one or more components (e.g., buffer  30   a , the first section of the memory  34 , and/or the like) of the switching module  14 , which are associated with routing the regular priority data packets, operate at a regular or normal power level. Similarly, while the switching module  14  is in the second level of regular power state, one or more components (e.g., buffer  30   b , the second section of the memory  34 , and/or the like) of the switching module  14 , which are associated with routing the high priority data packets, operate at a regular or normal power level. 
     As illustrated in  FIG. 2   b , an on-time period a2 associated with the timing curve  200   b  is relatively small compared to an on-time period a3 associated with the timing curve  200   c . Furthermore, as illustrated in  FIG. 2   b , a timing pattern A2 associated with the timing curve  200   b  is relatively small compared to a timing pattern A3 associated with the timing curve  200   c . As illustrated in  FIG. 2   b , the on-time periods a3 occur more frequently compared to occurrence of the on-time periods a2 (although the duration of each on-time period a3 is smaller than the duration of each on-time period a2). Furthermore, as illustrated in  FIG. 2   b , a duty cycle associated with the timing curve  200   c  (which is equal to (a3/(a3+b3))×100)) is smaller than a duty cycle associated with the timing curve  200   b  (which is equal to (a2/(a2+b2))×100)). 
     Accordingly, in various embodiments, high priority data packets are transmitted more frequently from the server blades  20   a , . . . ,  20 N, compared to regular priority data packets, thereby decreasing a latency period of high priority data packets (e.g., compared to a latency period of regular priority of data packets). However, as a number of high priority data packets routed by the switching module  14  is lower than a number of regular priority data packets routed by the switching module  14 , each on period a3 is smaller compared to each on period a2 (e.g., due to less time required for routing the lower number of high priority data packets). 
     In various embodiments, the duty cycles associated with the timing curves  200   b  and/or  200   c  are varied dynamically based at least in part on the load factor of the blade server system  10 . Such variations of the duty cycles may be similar to the variation of the duty cycle associated with the timing curve  200   a , as previously disclosed herein. 
     Selectively operating in the first level of low power state and the second level of low power state, by the switching module  14 , has several advantages. For example, the first level of low power state and the second level of low power state result in significant savings in power consumed by the switching module  14 , which also result in lower cooling requirements for the blade server system  10 . Furthermore, categorizing data packets in different priority groups, and having different duty cycles for the different priority groups of data packets also has several advantages. For example, as previously disclosed, high priority data packets are transmitted more frequently from the server blades  20   a , . . . ,  20 N, compared to regular priority data packets. This ensures that the blade server system  10  saves power through the various low power states, without sacrificing the ability to promptly and timely handling high priority data packets. 
       FIG. 3  illustrates a method  300  for operating the blade server system  10  of  FIG. 1 , in accordance with various embodiments of the present disclosure. Referring to  FIGS. 1 ,  2   b  and  3 , the method  300  includes, at  304 , categorizing (e.g., by the packet flow control module  18 ) each data packet of a plurality of data packets into one of at least two priority groups of data packets (e.g., a first priority group of data packets that correspond to the regular priority group of data packets, and a second priority group of data packets that correspond to the high priority group of data packets). 
     The method further comprises, at  308 , controlling (e.g., by the packet flow control module  18 ) transmission of data packets of the first priority group of data packets during a first off-time period (e.g., off-time period b2) such that during the first off-time period, data packets of the first priority group of data packets are prevented from being transmitted to a switching module (e.g., switching module  14 ) from one or more server blades (e.g., one or more of the server blades  20   a , . . . ,  20 N). At  308 , the packet flow control module  18  also causes the switching module to operate in a first level of low power state during the first off-time period. 
     The method further comprises, at  312 , controlling (e.g., by the packet flow control module  18 ) transmission of data packets of the first priority group of data packets during a first on-time period (e.g., on-time period a2) such that during the first on-time period, one or more data packets of the first priority group of data packets are transmitted to the switching module from the one or more server blades. During the first on-time period, the switching module may operate in the first level of regular power state, as previously disclosed. 
     The method further comprises, at  316 , controlling (e.g., by the packet flow control module  18 ) transmission of data packets of the second priority group of data packets during a second off-time period (e.g., off-time period b3) such that during the second off-time period, data packets of the second priority group of data packets are prevented from being transmitted to the switching module from the one or more server blades. At  316 , the packet flow control module  18  also causes the switching module to operate in a second level of low power state during the second off-time period. 
     The method further comprises, at  320 , controlling (e.g., by the packet flow control module  18 ) transmission of data packets of the second priority group of data packets during a second on-time period (e.g., on-time period a3) such that during the second on-time period, one or more data packets of the second priority group of data packets are transmitted to the switching module from the one or more server blades. During the first on-time period, the switching module may operate in the second level of regular power state, as previously disclosed. 
     Various operations of the method  300  may not occur in the sequence illustrated in  FIG. 3 . For example, one or more operations associated with blocks  308  and/or  312  may occur at least in part simultaneously with one or more operations associated with blocks  316  and/or  320 , as will be readily understood by those skilled in the art based at least in part on the teachings of the disclosure. Furthermore, although not illustrated in  FIG. 3 , one or more operations associated with blocks  308 , . . . ,  320  may be repeated for a plurality of times, as will be readily understood by those skilled in the art based at least in part on the teachings of the disclosure. 
       FIG. 4  is a block diagram of an illustrative system  400  suitable for practicing the embodiments of the present disclosure. As illustrated, system  400  includes one or more processors or processor cores  402 , and system memory  404 . For purposes of this disclosure, including the claims, the terms “processor” and “processor cores” may be considered synonymous, unless the context clearly requires otherwise. Additionally, system  400  includes mass storage devices  406  (such as diskette, hard drive, compact disc read only memory (CDROM) and so forth), input/output devices  408  (such as a display to render visual manifestation, a keyboard, a cursor control, and so forth) and communication interfaces  410  (such as network interface cards, modems and so forth). The elements of  FIG. 4  may be coupled to each other via system bus  412 , which represents one or more buses. In the case of multiple buses, they may be bridged by one or more bus bridges (not illustrated). 
     System memory  404  and mass storage  406  may be employed to store a working copy and a permanent copy of the programming instructions implementing all or a portion of earlier described functions, herein collectively denoted as  422 . The instructions  422  may be assembler instructions supported by processor(s)  402  or instructions that can be compiled from high level languages, such as C or other suitable high level programming languages. 
     A permanent copy of the programming instructions is stored into permanent storage  406  in the factory, or in the field, through, for example, a distribution medium (not shown), such as a compact disc (CD), or through communication interface  410  (from a distribution server (not shown)). That is, one or more distribution media having instructions  422  may be employed to distribute the instructions  422  and program various computing devices. 
     The system  400  is included in or is associated with the blade server system  10  of  FIG. 1 . In various embodiments, the system  400  includes a packet flow control module  418  communicatively coupled to the system bus  412 . The packet flow control module  418  is at least in part similar to the packet flow control module  18  of  FIG. 1 . Although not illustrated in  FIG. 4 , the system  400  may be communicatively coupled to a plurality of server blades (e.g., server blades  20   a , . . . ,  20 N of  FIG. 1 ) and a switching module (e.g., switching module  14  of  FIG. 1 ). 
     In various embodiments, one or more instructions associated with the packet flow control module  418  are stored as instructions  422 . In various embodiments, the system  400  (e.g., the processor  402 ) is configured to execute one or more instructions to cause the system  400  (e.g., the packet flow control module  418 ) to execute one or more operations of method  300  of  FIG. 3  (and/or one or more operations associated with controlling various operations of the blade server system  10 , as disclosed in this disclosure). 
     In embodiments of the present disclosure, an article of manufacture (not illustrated) implements one or more methods as disclosed herein. For example, in various embodiments, an article of manufacture may comprise a storage medium and a plurality of programming instructions stored in the storage medium and adapted to program a computing device to configure the computing device to execute one or more operations associated with controlling various operations of the blade server system  10  (e.g., one or more operations of method  300  of  FIG. 3 , one or more operations associated with controlling transmission of data packets in the blade server system  10 , and/or one or more operations associated with controlling a state (e.g., low power state, regular power state, etc.) of the switching module  14 , as disclosed in this disclosure). 
     Although specific embodiments have been illustrated and described herein, a wide variety of alternate and/or equivalent implementations may be substituted for the specific embodiment illustrated and described without departing from the scope of the present disclosure. This present disclosure covers all methods, apparatus, and articles of manufacture fairly falling within the scope of the appended claims either literally or under the doctrine of equivalents. For example, although the above discloses example systems including, among other components, software or firmware executed on hardware, it should be noted that such systems are merely illustrative and should not be considered as limiting. In particular, it is contemplated that any or all of the disclosed hardware, software, and/or firmware components could be embodied exclusively in hardware, exclusively in software, exclusively in firmware or in some combination of hardware, software, and/or firmware. This application is intended to cover any adaptations or variations of the embodiment disclosed herein.