|Publication number||US20100142536 A1|
|Application number||US 12/706,481|
|Publication date||Jun 10, 2010|
|Filing date||Feb 16, 2010|
|Priority date||Nov 30, 2004|
|Also published as||US7715384, US20060114901|
|Publication number||12706481, 706481, US 2010/0142536 A1, US 2010/142536 A1, US 20100142536 A1, US 20100142536A1, US 2010142536 A1, US 2010142536A1, US-A1-20100142536, US-A1-2010142536, US2010/0142536A1, US2010/142536A1, US20100142536 A1, US20100142536A1, US2010142536 A1, US2010142536A1|
|Inventors||Mohan Kalkunte, John Jeffrey Dull, Bruce H. Kwan, Venkateshwar Buduma|
|Original Assignee||Broadcom Corporation|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (1), Referenced by (3), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of U.S. patent application Ser. No. 11/289,497, filed on Nov. 30, 2005 which claims priority of U.S. Provisional Patent Application Ser. No. 60/631,548, filed on Nov. 30, 2004 and U.S. Provisional Patent Application Ser. No. 60/686,456, filed on Jun. 2, 2005. The subject matter of these earlier filed applications is hereby incorporated by reference.
The present invention relates to a network device in a data network and more particularly to a system and method of creating a logical port by logically linking multiple ports and for transmitting unicast packets through the logical port.
A packet switched network may include one or more network devices, such as a Ethernet switching chip, each of which includes several modules that are used to process information that is transmitted through the device. Specifically, the device includes an ingress module, a Memory Management Unit (MMU) and an egress module. The ingress module includes switching functionality for determining to which destination port a packet should be directed. The MMU is used for storing packet information and performing resource checks. The egress module is used for performing packet modification and for transmitting the packet to at least one appropriate destination port. One of the ports on the device may be a CPU port that enables the device to send and receive information to and from external switching/routing control entities or CPUs.
A current network device may support physical ports and logical/trunk ports, wherein each trunk port includes a set of physical external ports and the trunk port acts as a single link layer port. Ingress and destination ports on the device may be physical external ports or trunk ports. By logically combining multiple physical ports into a trunk port, the network may provide greater bandwidth for connecting multiple devices. If one port in the trunk fails, information may still be sent between connected devices through other active ports of the trunk. Therefore, trunk ports enable the network to provide greater redundancy between connected network devices.
In order to transmit information from one network device to another, the sending device has to determine if the packet is being transmitted to a trunk destination port. If a destination port is a trunk port, the sending network device must dynamically select a physical external port in the trunk on which to transmit the packet. The dynamic selection must account for load sharing between ports in a trunk so that outgoing packets are adequately distributed across the trunk.
Typically, each packet entering a network device may be one of a unicast packet, a broadcast packet, a multicast packet, or an unknown unicast packet. The unicast packet is transmitted to a specific destination address that can be determined by the receiving network device. However, the sending network device must select one port from the trunk group and adequately distribute packets across ports of the trunk group.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention that together with the description serve to explain the principles of the invention, wherein:
Reference will now be made to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
Device 100 may also include one or more internal fabric high speed ports, for example a HiGig.™, high speed port 108 a-108 x, one or more external Ethernet ports 109 a-109 x, and a CPU port 110. High speed ports 108 a-108 x are used to interconnect various network devices in a system and thus form an internal switching fabric for transporting packets between external source ports and one or more external destination ports. As such, high speed ports 108 a-108 x are not externally visible outside of a system that includes multiple interconnected network devices. CPU port 110 is used to send and receive packets to and from external switching/routing control entities or CPUs. According to an embodiment of the invention, CPU port 110 may be considered as one of external Ethernet ports 109 a-109 x. Device 100 interfaces with external/off-chip CPUs through a CPU processing module 111, such as a CMIC, which interfaces with a PCI bus that connects device 100 to an external CPU.
Network traffic enters and exits device 100 through external Ethernet ports 109 a-109 x. Specifically, traffic in device 100 is routed from an external Ethernet source port to one or more unique destination Ethernet ports 109 a-109 x. In one embodiment of the invention, device 100 supports physical Ethernet ports and logical (trunk) ports. A physical Ethernet port is a physical port on device 100 that is globally identified by a global port identifier. In an embodiment, the global port identifier includes a module identifier and a local port number that uniquely identifies device 100 and a specific physical port. The trunk ports are a set of physical external Ethernet ports that act as a single link layer port. Each trunk port is assigned a global a trunk group identifier (TGID). According to an embodiment, device 100 can support up to 128 trunk ports, with up to 8 members per trunk port, and up to 29 external physical ports. Destination ports 109 a-109 x on device 100 may be physical external Ethernet ports or trunk ports. If a destination port is a trunk port, device 100 dynamically selects a physical external Ethernet port in the trunk by using a hash to select a member port. As explained in more detail below, the dynamic selection enables device 100 to allow for dynamic load sharing between ports in a trunk.
Once a packet enters device 100 on a source port 109 a-109 x, the packet is transmitted to ingress module 102 for processing. Packets may enter device 100 from a XBOD or a GBOD. The XBOD is a block that has one 10 GE/12 G MAC and supports packets from high speed ports 108 a-108 x. The GBOD is a block that has 12 10/100/1 G MAC and supports packets from ports 109 a-109 x.
According to one embodiment of the invention, the ingress pipeline includes one 1024-bit cell data holding register 202 and one 96-bit module header register 204 for each XBOD or GBOD. Data holding register 202 accumulates the incoming data into one contiguous 128-byte cell prior to arbitration and the module header register 204 stores an incoming 96-bit module header for use later in ingress pipeline 200. Specifically, holding register 202 stores incoming status information.
Ingress pipeline 200 schedules requests from the XBOD and GBOD every six clock cycles and sends a signal to each XBOD and GBOD to indicate when the requests from the XBOD and GBOD will be scheduled. CPU processing module 111 transfers one cell at a time to ingress module 102 and waits for an indication that ingress module 102 has used the cell before sending subsequent cells. Ingress pipeline 200 multiplexes signals from each of XBOD, GBOD and CPU processing based on which source is granted access to ingress pipeline 200 by arbiter 206. Upon receiving signals from the XBOD or GBOD, a source port is calculated by register buffer 202, the XBOD or GBOD connection is mapped to a particular physical port number on device 100 and register 202 passes information relating to a scheduled cell to arbiter 206.
When arbiter 206 receives information from register buffer 202, arbiter 206 may issue at least one of a packet operation code, an instruction operation code or a FP refresh code, depending on resource conflicts. According to one embodiment, the arbiter 206 includes a main arbiter 207 and auxiliary arbiter 209. The main arbiter 207 is a time-division multiplex (TDM) based arbiter that is responsible for scheduling requests from the GBOD and the XBOD, wherein requests from main arbiter 207 are given the highest priority. The auxiliary arbiter 209 schedules all non XBOD/GBOD requests, including CPU packet access requests, CPU memory/register read/write requests, learn operations, age operations, CPU table insert/delete requests, refresh requests and rate-limit counter refresh request. Auxiliary arbiter's 209 requests are scheduled based on available slots from main arbiter 207.
When the main arbiter 207 grants an XBOD or GBOD a slot, the cell data is pulled out of register 202 and sent, along with other information from register 202, down ingress pipeline 200. After scheduling the XBOD/GBOD cell, main arbiter 207 forwards certain status bits to auxiliary arbiter 209.
The auxiliary arbiter 209 is also responsible for performing all resource checks, in a specific cycle, to ensure that any operations that are issued simultaneously do not access the same resources. As such, auxiliary arbiter 209 is capable of scheduling a maximum of one instruction operation code or packet operation code per request cycle. According to one embodiment, auxiliary arbiter 209 implements resource check processing and a strict priority arbitration scheme. The resource check processing looks at all possible pending requests to determine which requests can be sent based on the resources that they use. The strict priority arbitration scheme implemented in an embodiment of the invention requires that CPU access request are given the highest priority, CPU packet transfer requests are given the second highest priority, rate refresh request are given the third highest priority, CPU memory reset operations are given the fourth highest priority and Learn and age operations are given the fifth highest priority by auxiliary arbiter 209. Upon processing the cell data, auxiliary arbiter 209 transmits packet signals to configuration stage 208.
Configuration stage 208 includes a port table for holding all major port specific fields that are required for switching, wherein one entry is associated with each port. The configuration stage 208 also includes several registers. When the configuration stage 208 obtains information from arbiter 206, the configuration stage 208 sets up the inputs for the port table during a first cycle and multiplexes outputs for other port specific registers during a second cycle. At the end of the second cycle, configuration stage 208 sends output to parser stage 210.
Parser stage 210 manages an ingress pipeline buffer which holds the 128-byte cell as lookup requests traverse pipeline 200. When the lookup request reaches the end of pipeline 200, the data is pulled from the ingress pipeline buffer and sent to MMU 104. If the packet is received on a high speed port, a 96-bit module header accompanying the packet is parsed by parser stage 210. After all fields have been parsed, parser stage 210 writes the incoming cell data to the ingress pipeline buffer and passes a write pointer down the pipeline. Since the packet data is written to the ingress pipeline buffer, the packet data need not be transmitted further and the parsed module header information may be dropped. Discard stage 212 then looks for various early discard conditions and, if one or more of these conditions are present, discard stage drops the packet and/or prevents it from being sent through the chip.
Switching stage 213 performs address resolution processing and other switching on incoming packets. According to an embodiment of the invention, switching stage 213 includes a first switch stage 214 and a second switch stage 216. First switch stage 214 resolves any drop conditions, performs BPDU processing, checks for layer 2 source station movement and resolves most of the destination processing for layer 2 and layer 3 unicast packets, layer 3 multicast packets and IP multicast packets. The first switch stage 214 also performs protocol packet control switching by optionally copying different types of protocol packets to the CPU or dropping them. The first switch stage 214 further performs all source address checks and determines if the layer 2 entry needs to get learned or re-learned for station movement cases. The first switch stage 214 further performs destination calls to determine how to switch packet based on a destination switching information. Specifically, the first switch stage 214 figures out the destination port for unicast packets or port bitmap of multicast packets, calculates a new priority, optionally traps packets to the CPU and drops packets for various error conditions. The first switch stage 214 further handles high speed switch processing separate from switch processing from port 109 a-109 i and switches the incoming high speed packet based on the stage header operation code.
The second switch stage 216 then performs Field Processor (FP) action resolution, source port removal, trunk resolution, high speed trunking, port blocking, CPU priority processing, end-to-end Head of Line (HOL) resource check, resource check, mirroring and maximum transfer length (MTU) checks for verifying that the size of incoming/outgoing packets is below a maximum transfer length. The second switch stage 216 takes first switch stage 216 switching decision, any layer routing information and FP redirection to produce a final destination for switching. The second switch stage 216 also removes the source port from the destination port bitmap and performs trunk resolution processing for resolving the trunking for the destination port for unicast packets, the ingress mirror-to-port and the egress mirror-to-port. The second switch stage 216 also performs high speed trunking by checking if the source port is part of a high speed trunk group and, if it is, removing all ports of the source high speed trunk group. The second switch stage 216 further performs port blocking by performing masking for a variety of reasons, including meshing and egress masking.
As noted above, an embodiment of device 100 may support up to 128 trunk ports with up to 8 members per trunk port. As such, table 400 is a 128 entry table, wherein each entry includes fields for eight ports. Therefore, returning to
Specifically, in one embodiment of the invention, since each entry of trunk group table includes eight fields that are associated with trunk group ports, three bits are selected from each byte of the fields in the RTAG hash to represent 8 bits. So if the RTAG value is 1, SA[0:2], SA[8:10], SA[16:18], SA[32:34] and SA[40:42], VLAN[0:2], VLAN [8:10], EtherType[0:2], EtherType[8:10], SRC_MODID[0:2] and SRC_PORT[0:2] are XORed to obtain a three bit value that is used to index trunk group table 400. If the RTAG value is 2, DA[0:2], DA[8:10], DA[16:18], DA[32:34], SA[40:42], VLAN[0:2], VLAN [8:10], EtherType[0:2], EtherType[8:10], SRC_MODID[0:2] and SRC PORT[0:2] are XORed to obtain a three bit value that is used to index trunk group table 400. If the RTAG value is 3, SA[0:2], SA[8:10], SA[16:18], SA[32:34], SA[40:42], DA[0:2], DA[8:10], DA[16:18], DA[32:34], DA[40:42], VLAN[0:2], VLAN [8:10], EtherType[0:2], EtherType[8:10], SRC_MODID[0:2] and SRC_PORT[0:2] are XORed to obtain a three bit value that is used to index trunk group table 400.
If the RTAG value is 4, SIP[0:2], SIP[8:10], SIP[16:18], SIP[32:34], SIP[40:42], SIP[48:50], SIP[56:58], SIP[66:64], SIP[72:74], SIP[80:82], SIP[88:90], SIP[96:98], SIP[104:106], SIP[112:114], SIP[120:122], TCP_SPORT[0:2] and TCP_SPORT[8:10] are XORed to obtain a three bit value that is used to index trunk group table 400. If the RTAG value is 5, DIP[0:2], DIP[8:10], DIP[16:18], DIP[32:34], DIP[40:42], DIP[48:50], DIP[56:58], DIP[66:64], DIP[72:74], DIP[80:82], DIP[88:90], DIP[96:98], DIP[104:106], DIP[112:114], DIP[120:122], TCP_DPORT[0:2] and TCP_SPORT[8:10] are XORed to obtain a three bit value that is used to index trunk group table 400.
For example, in
The above-discussed configuration of the invention is, in a preferred embodiment, embodied on a semiconductor substrate, such as silicon, with appropriate semiconductor manufacturing techniques and based upon a circuit layout which would, based upon the embodiments discussed above, be apparent to those skilled in the art. A person of skill in the art with respect to semiconductor design and manufacturing would be able to implement the various modules, interfaces, and tables, buffers, etc. of the present invention onto a single semiconductor substrate, based upon the architectural description discussed above. It would also be within the scope of the invention to implement the disclosed elements of the invention in discrete electronic components, thereby taking advantage of the functional aspects of the invention without maximizing the advantages through the use of a single semiconductor substrate.
With respect to the present invention, network devices may be any device that utilizes network data, and can include switches, routers, bridges, gateways or servers. In addition, while the above discussion specifically mentions the handling of packets, packets, in the context of the instant application, can include any sort of datagrams, data packets and cells, or any type of data exchanged between network devices.
The foregoing description has been directed to specific embodiments of this invention. It will be apparent, however, that other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true spirit and scope of the invention.
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|US20020009081 *||Jun 11, 2001||Jan 24, 2002||Broadcom Corporation||Gigabit switch with frame forwarding and address learning|
|Citing Patent||Filing date||Publication date||Applicant||Title|
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|US8014390||Nov 30, 2005||Sep 6, 2011||Broadcom Corporation||Policy based routing using a fast filter processor|
|Cooperative Classification||H04L49/3009, H04L49/352, H04L49/254, H04L49/103, H04L49/602, H04L49/3072|