Method and apparatus for a shared I/O network interface controller

• US 20050053060A1
• Filed: 07/30/2004
• Published: 03/10/2005
• Est. Priority Date: 01/21/2003
• Status: Active Grant

• Current Assignee: Mellanox Technologies Limited (NVIDIA Corporation)
• Original Assignee: NextIO Incorporated
• Inventors: Pettey, Christopher J.
• Granted Patent: US 8,346,884 B2
• Time in Patent Office: Days
• US Class Current: 370/385
• CPC Class Codes: H04L 45/74 Address processing for routing
• CPC Class Codes: H04L 61/00 Network arrangements, protocols or services for addressing or naming
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 67/1001 for accessing one among a plurality of replicated servers
• CPC Class Codes: H04L 67/1017 based on a round robin mechanism
• CPC Class Codes: H04L 67/1097 for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS]
• CPC Class Codes: H04L 67/63 Routing a service request depending on the request content or context
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

An apparatus and method is provided for interfacing a number of computer servers (or operating system domains) to a network such as Ethernet through a shared network interface controller (NIC) which is part of the load-store architecture of the operating system domains. The network interface controller includes a bus interface to couple the controller to a load-store domain bus (such as PCI-Express), the bus including header information to associate data on the bus with an originating operating system domain. The controller also includes transmit/receive logic to connect it to the network. In between the bus interface and the transmit/receive logic is buffering to temporarily store data coming either from the operating system domains or the network. The buffered data is tagged within an identifier to associate it with one or more of the operating system domains. Association logic is further provided to allow the controller to designate, and later lookup which destination MAC address (on the Ethernet side) is associated with which operating system domain. Control Status Registers (CSR'"'"'s) specific to an operating system domain are duplicated and made available for each domain. Descriptor Register files are also duplicated for each operating system domain. A number of direct memory access (DMA) engines are provided to improve throughput. And, packet replication logic, along with filters (perfect and hash) and VLAN tables are used for looping back packets originating from one of the operating system domains to one or more of the other operating system domains, for server to server communication, multicast and broadcast operations.

Claims

1. A shareable network interface controller to be shared within the load-store architecture of a plurality of operating system domains, comprising:

transmit/receive logic for coupling the controller to a network to transmit/receive network communication;

bus interface and operating system domain identification logic, for interfacing the controller to the plurality of operating system domains (OSD'"'"'s), and for associating OSD communication to and from said bus interface with ones of the plurality of OSD'"'"'s;

association logic, coupled to said transmit/receive logic, for associating said network communication with ones of the plurality of OSD'"'"'s;

wherein by associating said network communication with ones of the plurality of OSD'"'"'s, and associating said OSD communication with ones of the plurality of OSD'"'"'s, the shared controller provides communication between the plurality of OSD'"'"'s and said network.

2. The shareable network interface controller as recited in claim 1 wherein the shareable network interface controller is a shareable Ethernet controller.

3. The shareable network interface controller as recited in claim 2 wherein said shareable Ethernet controller supports 10/100 megabit, 1 gigabit, and/or 10 gigabit network communication.

4. The shareable network interface controller as recited in claim 1 wherein the load-store architecture comprises resources directly accessible by the plurality of OSD'"'"'s using load and/or store instructions.

5. The shareable network interface controller as recited in claim 4 wherein said resources comprise memory spaces for each of the plurality of OSD'"'"'s.

6. The shareable network interface controller as recited in claim 1 wherein each of the plurality of OSD'"'"'s is unaware that it is sharing the shareable network interface controller with another one of the plurality of OSD'"'"'s.

7. The shareable network interface controller as recited in claim 1 wherein each of the plurality of OSD'"'"'s comprise:

a processing complex; and

memory, coupled to said processing complex.

8. The shareable network interface controller as recited in claim 7 wherein said processing complex comprises at least one processor.

9. The shareable network interface controller as recited in claim 1 wherein said transmit/receive logic stores said network communication from/to at least two of the plurality of OSD'"'"'s, simultaneously.

10. The shareable network interface controller as recited in claim 1 wherein said transmit/receive logic comprises:

a transmit fifo for storing said network communication to be transmitted to said network; and

a receive fifo, for storing network communication received from said network.

11. The shareable network interface controller as recited in claim 10 wherein said transmit fifo comprises a virtual fifo for storing said network communication from a plurality of OSD'"'"'s, simultaneously.

12. The shareable network interface controller as recited in claim 10 wherein said receive fifo comprises a virtual fifo for storing said network communication destined for a plurality of OSD'"'"'s, simultaneously.

13. The shareable network interface controller as recited in claim 10 wherein said transmit fifo and said receive fifo each further comprise:

OSD management logic, for associating data within each of said fifo'"'"'s with corresponding OSD'"'"'s.

14. The shareable network interface controller as recited in claim 1 wherein said transmit/receive logic comprises:

a virtual fifo for storing both said network communication to be transmitted to said network, and said network communication received from said network, simultaneously.

15. The shareable network interface controller as recited in claim 14 wherein simultaneously indicates that transmit network communication and receive network communication coexists within said virtual fifo.

16. The shareable network interface controller as recited in claim 14 wherein said virtual fifo further comprises OSD management logic, for associating data within said virtual fifo with corresponding OSD'"'"'s.

17. The shareable network interface controller as recited in claim 1 wherein said transmit/receive logic comprises:

a plurality of transmit fifo'"'"'s, one for each of the plurality of OSD'"'"'s; and

a plurality of receive fifo'"'"'s, one for each of the plurality of OSD'"'"'s.

18. The shareable network interface controller as recited in claim 1 wherein said network is an Ethernet network.

19. The shareable network interface controller as recited in claim 1 wherein said network is a packet based network.

20. The shareable network interface controller as recited in claim 1 wherein said network communication comprises packet based communication.

21. The shareable network interface controller as recited in claim 1 wherein said bus interface and operating system domain identification logic comprises:

a bus interface to a load-store architecture bus; and

operating system domain identification logic, coupled to said bus interface.

22. The shareable network interface controller as recited in claim 21 wherein said load-store architecture bus comprises a packet based serial communication bus.

23. The shareable network interface controller as recited in claim 21 wherein said load-store architecture bus comprises a PCI-Express+ bus.

24. The shareable network interface controller as recited in claim 23 wherein said PCI-Express+ bus comprises a PCI-Express bus which includes an OSD header.

25. The shareable network interface controller as recited in claim 24 wherein said OSD header identifies an associated OSD for packets transmitted over said PCI-Express bus.

26. The shareable network interface controller as recited in claim 24 wherein said operating system domain identification logic examines said OSD header for packets received by said bus interface to determine which of the plurality of OSD'"'"'s transmitted said packets, and places said OSD header into packets to be transmitted by said bus interface to identify which of the plurality of OSD'"'"'s said transmitted packets are for.

27. The shareable network interface controller as recited in claim 1 wherein said association logic comprises:

a look up table for storing OSD and MAC address associations.

28. The shareable network interface controller as recited in claim 27 wherein said look up table comprises:

a plurality of OSD entries; and

a plurality of MAC address entries;

wherein each of said plurality of OSD entries is associated with at least one of said plurality of MAC address entries.

29. The shareable network interface controller as recited in claim 28 wherein each of said OSD entries comprise a bit representation for identifying an upstream operating system domain.

30. The shareable network interface controller as recited in claim 29 wherein said bit representation comprises 3-bits for designating eight distinct operating system domains.

31. The shareable network interface controller as recited in claim 29 wherein said bit representation comprises 8-bits for designating eight or more distinct operating system domains.

32. The shareable network interface controller as recited in claim 28 wherein each of said plurality of MAC address entries comprise a unique machine address.

33. The shareable network interface controller as recited in claim 28 wherein by associating a MAC address entry with an OSD entry, the controller can associate said network communication with ones of said plurality of OSD entries based on a destination MAC address within said network communication.

34. The shareable network interface controller as recited in claim 28 wherein by associating a MAC address entry with an OSD entry, the controller can associate said OSD communication with ones of said plurality of MAC address entries.

35. The shareable network interface controller as recited in claim 1 further comprising:

a plurality of control status register sets (CSR'"'"'s), coupled to said bus interface and operating system domain identification logic, each available to be associated with a unique one of the plurality of operating system domains.

36. The shareable network interface controller as recited in claim 35 wherein each of said plurality of control register sets comprise:

a head pointer register, for storing a head pointer associated with a descriptor block in a memory associated with one of the plurality of OSD'"'"'s; and

a tail pointer register, for storing a tail pointer associated with said descriptor block in said memory associated with said one of the plurality of OSD'"'"'s.

37. The shareable network interface controller as recited in claim 35 wherein each of the plurality of operating system domains must be associated with a different one of said plurality of control status register sets.

38. The shareable network interface controller as recited in claim 35 wherein unique one of the plurality of operating system domains implies that each of said plurality of control status register sets is associated with no more than one of the plurality of operating system domains.

39. The shareable network interface controller as recited in claim 1 further comprising:

a descriptor cache, coupled to said bus interface and operating system domain identification logic, for storing descriptors retrieved from the plurality of operating system domains.

40. The shareable network interface controller as recited in claim 39 wherein said descriptors define memory locations within memories of the plurality of operating system domains where said OSD communication is transferred to/from the controller.

41. The shareable network interface controller as recited in claim 39 wherein said descriptor cache comprises:

a plurality of descriptor caches, each available to be associated with one of the plurality of operating system domains; and

descriptor arbitration logic, coupled to said plurality of descriptor caches, for associating each of the plurality of descriptor caches with each of the plurality of operating system domains.

42. The shareable network interface controller as recited in claim 39 wherein said descriptor cache comprises:

a virtual descriptor cache, for storing descriptors from the plurality of operating system domains; and

tag logic, coupled to the virtual descriptor cache, for associating each of said descriptors with their associated one of the plurality of operating system domains.

43. The shareable network interface controller as recited in claim 42 wherein said virtual descriptor cache further comprises:

a virtual transmit descriptor cache for storing descriptors for said OSD communication to be transmitted as said network communication; and

a virtual receive descriptor cache for storing descriptors for said network communication to be received as said OSD communication.

44. The shareable network interface controller as recited in claim 1 further comprising:

a plurality of direct memory access (DMA) engines, said engines used by the controller to DMA said OSD communication from the plurality of OSD'"'"'s, and to DMA said network communication to the plurality of OSD'"'"'s.

45. The shareable network interface controller as recited in claim 44 wherein said plurality of DMA engines further comprise:

DMA arbitration, coupled to said plurality of DMA engines, for arbitrating selection of said plurality of DMA engines among the plurality of OSD'"'"'s.

46. The shareable network interface controller as recited in claim 1 further comprising:

packet replication logic, coupled to said bus interface and operating system domain identification logic, for re-storing said OSD communication into said transmit/receive logic for multicast or broadcast communication.

47. The shareable network interface controller as recited in claim 46 wherein said multicast or broadcast communication comprises communication from one of the plurality of OSD'"'"'s to more than one destination MAC address on said network.

48. The shareable network interface controller as recited in claim 46 wherein said packet replication logic places said OSD communication within a receive portion of said transmit/receive logic when a loopback communication occurs.

49. The shareable network interface controller as recited in claim 48 wherein said loopback communication occurs when a destination MAC address for said OSD communication corresponds to a MAC address within said association logic.

50. A network interface controller (NIC) which provides an interface between a network and a plurality of operating system domains, the controller existing within the load-store domain of each of the plurality of operating system domains (OSD'"'"'s), the controller comprising:

a bus interface between the plurality of operating system domains and the controller;

a network interface between the network and the controller; and

association logic, coupled to both said bus interface and said network interface to associate data coming from the network with at least one of the plurality of operating system domains.

51. The network interface controller as recited in claim 50 wherein the controller comprises a shared Ethernet controller.

52. The network interface controller as recited in claim 50 wherein the network is an Ethernet network.

53. The network interface controller as recited in claim 50 wherein each of the plurality of operating system domains comprise:

at least one processor;

a memory coupled to said at least one processor; and

an operating system executing on said processor.

54. The network interface controller as recited in claim 50 wherein each of the plurality of operating system domains comprise a computer server.

55. The network interface controller as recited in claim 54 wherein said computer server is a blade server.

56. The network interface controller as recited in claim 50 wherein the load-store domain of each of the plurality of operating system domains comprises memory which is accessed by load and store instructions executing within each of the plurality of operating system domains.

57. The network interface controller as recited in claim 50 wherein each of the plurality of operating system domains comprise:

at least one processor;

a memory coupled to said at least one processor;

an operating system executing on said at least one processor;

a load instruction for loading data from said memory into said at least one processor; and

a store instruction for storing data from said at least one processor into said memory;

wherein each of the plurality of operating system domains communicates with the controller using said load instruction and said store instruction.

58. The network interface controller as recited in claim 50 wherein each of the plurality of operating system domains communicates with the network interface controller using a software driver which is loaded into each of the plurality of operating system domains.

59. The network interface controller as recited in claim 58 wherein said software driver is mapped within the load-store domain of each of the plurality of operating system domains.

60. The network interface controller as recited in claim 50 wherein said bus interface comprises:

an interface to a load-store domain network which transfers data from each of the plurality of operating system domains to the controller; and

OSD identification logic, which determines for said data received from said load-store domain network, which of the plurality of operating system domains is associated with said data.

61. The network interface controller as recited in claim 60 wherein said load-store domain network comprises PCI-Express+.

62. The network interface controller as recited in claim 61 wherein said PCI-Express+ comprises PCI-Express with OSD header information.

63. The network interface controller as recited in claim 62 wherein said OSD header information comprises a header included with PCI-Express information which identifies which of the plurality of operating system domains is associated with said PCI-Express information.

64. The network interface controller as recited in claim 50 wherein said network interface comprises transmit/receive logic for buffering transmit data to be transmitted to the network, and for buffering receive data received from the network.

65. The network interface controller as recited in claim 64 wherein said transmit/receive logic comprises:

a virtual fifo for storing said transmit data and said receive data;

wherein said transmit data is tagged to identify which of the plurality of operating system domains said data came from; and

wherein said receive data is tagged to identify which of the plurality of operating system domains should receive said receive data.

66. The network interface controller as recited in claim 64 wherein said transmit/receive logic comprises:

a plurality of transmit fifo'"'"'s, each corresponding to one of the plurality of operating system domains; and

a plurality of receive fifo'"'"'s, each corresponding to one of the plurality of operating system domains.

67. The network interface controller as recited in claim 64 wherein said transmit/receive logic comprises:

a virtual transmit fifo for storing said transmit data from the plurality of operating system domains; and

a virtual receive fifo for storing said receive data received from the network.

68. The network interface controller as recited in claim 67 wherein said receive data is tagged with an OSD identifier after it is received from the network into the controller.

69. The network interface controller as recited in claim 68 wherein said OSD identifier designates which of the plurality of operating system domains should receive the data.

70. The network interface controller as recited in claim 68 wherein said OSD identifier is provided by said association logic.

71. The network interface controller as recited in claim 70 wherein said association logic correlates a MAC address within said receive data with a corresponding OSD.

72. The network interface controller as recited in claim 50 wherein said association logic comprises a lookup table which contains a plurality of MAC address which are correlated to a plurality of OSD'"'"'s.

73. The network interface controller as recited in claim 72 wherein each of said plurality of OSD'"'"'s is associated with at least one of said plurality of MAC addresses.

74. The network interface controller as recited in claim 72 wherein data received from the network contains a destination MAC address.

75. The network interface controller as recited in claim 74 wherein when said data is received from the network into the controller, said destination MAC address is read from said data, and said lookup table is read to determine an associated OSD for said data.

76. The network interface controller as recited in claim 50 further comprising:

a non volatile memory for storing a plurality of MAC addresses.

77. The network interface controller as recited in claim 50 further comprising:

a plurality of direct memory access (DMA) engines; and

DMA arbitration, coupled to said plurality of DMA engines;

wherein said plurality of DMA engines are selected by said DMA arbitration to perform data transfer from the plurality of operating system domains to the controller.

78. The network interface controller as recited in claim 50 further comprising:

a plurality of control status register (CSR) sets;

which are to be associated with the plurality of OSD'"'"'s.

79. The network interface controller as recited in claim 78 wherein said plurality of CSR sets each comprise:

a head pointer register for storing a head pointer to a location within its associated OSD; and

a tail pointer register for storing a tail pointer to a location within its associated OSD.

80. The network interface controller as recited in claim 50 further comprising:

descriptor logic, for storing a plurality of descriptors for the plurality of operating system domains.

81. The network interface controller as recited in claim 80 wherein said descriptor logic comprises:

a virtual descriptor cache, for storing transmit and receive descriptors for the plurality of operating system domains; and

tags, coupled to said virtual descriptor cache, for tagging each of said descriptors with their associated one of the plurality of operating system domains.

82. The network interface controller as recited in claim 80 wherein said descriptor logic comprises:

a virtual transmit descriptor cache for storing transmit descriptors for the plurality of operating system domains; and

a virtual receive descriptor cache for storing receive descriptors for the plurality of operating system domains.

83. The network interface controller as recited in claim 80 wherein said descriptor logic comprises:

a plurality of transmit descriptor caches, each of said caches associated with one of the plurality of operating system domains; and

a plurality of receive descriptor caches, each of said caches associated with one of the plurality of operating system domains;

wherein transmit descriptors are stored in said plurality of transmit descriptor caches; and

wherein receive descriptors are stored in said plurality of receive descriptor caches.

84. A shared network interface controller (NIC) to allow a plurality of computer servers to interface to an Ethernet network, the controller comprising:

a bus interface to couple the controller to a packet based load-store serial link, said load-store serial link coupling each of the plurality of computer servers to the controller;

server identification logic, coupled to said bus interface, for identifying packets received by said bus interface with ones of the plurality of computer servers;

buffering logic, coupled to said server identification logic, to store said packets received by said bus interface, along with tags which associate said packets with ones of the plurality of computer servers;

association logic, coupled to said buffering logic, for determining MAC addresses for said packets utilizing said tags; and

transmit/receive logic, coupled to the Ethernet network, and to said association logic, for transmitting said packets to the Ethernet network, and for receiving packets from said Ethernet network;

wherein by associating packets with ones of the plurality of computer servers, and buffering the packets between the plurality of computer servers and the Ethernet network, the shared network interface controller provides an Ethernet interface for all of the plurality of computer servers via said packet based load-store serial link.

85. The shared network interface controller as recited in claim 84 wherein said packet based load-store serial link comprises:

PCI-Express; and

a computer server identifier.

86. The shared network interface controller as recited in claim 84 wherein said packet based load-store serial link comprises:

PCI-Express+.

87. The shared network interface controller as recited in claim 84 wherein said buffering logic comprises:

a virtual fifo, for storing packets transmitted from the plurality of computer servers, and for storing packets received from the Ethernet network.

88. The shared network interface controller as recited in claim 84 wherein said association logic comprises a lookup table for associating the plurality of computer servers with MAC addresses.

89. The shared network interface controller as recited in claim 84 further comprising:

a switch, locating in between the plurality of computer servers and the shared network interface controller, for coupling the plurality of computer servers to said load-store serial link.

90. A blade server environment comprising:

a plurality of blade servers;

a shared switch for coupling to the plurality of blade servers, and for providing communication between the plurality of blade servers and a downstream endpoint, the downstream endpoint comprising a shared network interface controller, said controller comprising;

a bus interface for coupling said controller to said shared switch;

identification logic, for determining which of the plurality of blade servers is associated with data packets received by said controller;

transmit/receive logic, for coupling said controller to an Ethernet network;

buffer logic, coupled to said bus interface and to said transmit/receive logic, for buffering said data packets received by said controller, either from said shared switch, or from said Ethernet network; and

association logic, coupled to said buffer logic, for determining from a MAC address, which of said blade servers should be associated with said data packets.

91. A method for sharing a network interface controller by a plurality of operating system domains, the method comprising:

providing a load-store domain link between the controller and the plurality of operating system domains;

providing OSD identification for data transmitted over the load-store domain link;

providing an interface between the controller and a network;

buffering data between the load-store domain link and the network; and

associating the buffered data with the plurality of operating system domains, said associating utilizing association logic to associate MAC addresses within the buffered data with ones of the plurality of operating system domains.

92. The method for sharing a network interface controller as recited in claim 91 wherein the load-store domain link comprises PCI-Express, including header information for designating an operating system domain for packets transferred over the load-store domain link.

93. The method for sharing a network interface controller as recited in claim 91 wherein said buffering is provided by a virtual fifo.

94. The method for sharing a network interface controller as recited in claim 93 wherein the virtual fifo further comprises tags which correlate the buffered data with ones of the plurality of operating system domains.

95. The method for sharing a network interface controller as recited in claim 91 wherein the association logic comprises a lookup table containing MAC addresses and OSD headers.

96. A method for correlating Ethernet packets within a shared network interface controller with a plurality of upstream operating system domains, comprising:

receiving the packets into the shared network interface controller;

associating the packets with the plurality of upstream operating system domains by correlating destination MAC addresses within the packets with ones of the plurality of upstream operating system domains;

caching descriptors for each of the plurality of upstream operating system domains which define where in their memories the packets are to be transferred; and

transferring the packets, per the descriptors, to the plurality of upstream operating system domains via a load-store link which allows the packets to be tagged with information which associates the packets with their upstream operating system domain.

97. A method for transmitting packets from a plurality of operating system domains to an Ethernet network thru a shared network interface controller, comprising:

requesting a packet transmit from one of the plurality of operating system domains to the controller;

tagging the request with an OSD header to associate the request with its operating system domain;

transmitting the request to the shared network interface controller;

within the shared network interface controller, correlating the request with its operating system domain;

utilizing the OSD header for the request to determine associated descriptors for the request;

transferring data from the operating system domain, corresponding to the request utilizing the associated descriptors;

buffering the transferred data; and

transmitting the buffered data to the Ethernet network.

98. A shared network interface controller within the load-store domain of a plurality of operating system domains, for interfacing the plurality of operating system domains to a network, the controller comprising:

a bus interface, for interfacing the controller to a plurality of operating system domains;

transmit/receive logic, for interfacing the controller to a network; and

packet replication logic, coupled to said bus interface, for detecting whether packets received from a first one of the plurality of operating system domains is destined for a second one of the plurality of operating system domains, and if said packets are destined for said second one of the plurality of operating system domains, said logic causing said packets to be transferred to said second one of the plurality of operating system domains.

99. The shared network interface controller as recited in claim 98 wherein if said packets are detected to be destined for said second one of the plurality of operating system domains, they are not transmitted to said network.

100. The shared network interface controller as recited in claim 98 wherein said packets detected to be destined for said second one of the plurality of operating system domains are referred to as loopback packets.

101. The shared network interface controller as recited in claim 98 wherein said packet replication logic comprises:

filter/vlan logic, for comparing multicast packets with filters established for each of the plurality of operating system domains to determine whether said multicast packets are destined for said second one of the plurality of operating system domains.

102. The shared network interface controller as recited in claim 101 wherein said filters comprise:

hash filters;

perfect filters; and

virtual lan filters.

103. The shared network interface controller as recited in claim 98 wherein said packets detected to be destined for said second one of the plurality of operating system domains are referred to as multicast packets.

104. The shared network interface controller as recited in claim 98 wherein said packets detected to be destined for said second one of the plurality of operating system domains are referred to as broadcast packets.

105. A method for determining a loopback condition within a shared network interface controller that is coupled to first and second operating system domains within their load-store architecture, the method comprising:

determining whether a packet transmitted by the first operating system domain is destined for the second operating system domain, the first and second operating system domains interfaced to each other, and to a network, through the shared network interface controller;

if the packet is destined for the second operating system domain, forwarding the packet to the second operating system domain, and not forwarding the packet to the network; and

if the packet is not destined for the second operating system domain, forwarding the packet to the network.

106. The method for determining a loopback condition, as recited in claim 105 wherein said step of determining comprises:

examining a destination MAC address of the packet; and

determining whether the destination MAC address is associated with the second operating system domain.

107. The method for determining a loopback condition, as recited in claim 105 wherein said step of determining comprises:

determining whether the packet is a multicast packet, and if so;

examining filter logic to establish whether the second operating system domain should receive the multicast packet.

108. The method for determining a loopback condition as recited in claim 105 wherein the filter logic comprises:

filter tables for the second operating system domain.

109. The method for determining a loopback condition as recited in claim 105 wherein said step of determining comprises:

determining whether the packet is a broadcast packet, and if so;

examining filter logic to establish whether the second operating system domain should receive the broadcast packet.