Trunking in a matrix

Abstract

A multistage switch includes a matrix of coupled switch devices. A logical link comprising a plurality of physical links couples a destination through the plurality of physical links to a plurality of ports in the multistage switch. Each switch device performs trunk aware forwarding to reduce the forwarding of received frames through the matrix of coupled switch devices to the destination in order to reduce unnecessary traffic in the multistage switch.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a plurality of external ports;   a plurality of devices organized into a plurality rows, each of the rows including a first fan-in/fan-out device, a second fan-in/fan-out device, and one or more switch devices, wherein:
 each device in a row is associated with a different respective stage of a plurality of stages; 
 certain of the devices in a row are connected to each other through internal output ports; 
 the first and second fan-in/fan-out devices are coupled to a number of the plurality of external ports and are configured to receive a data frame, the data frame being associated with a logical link implemented in the apparatus; and 
 the data frame is communicated on physical paths between one or more of the plurality of devices based on a forward vector determined based on:
 a first vector component determined based at least in part on header information of the received data frame; 
 a second vector component determined based at least in part on a destination address of the received data frame; and 
 a third vector component determined based at least in part on the external port via which the data frame was received. 
 
   
     
     
         2 . The apparatus as claimed in  claim 1 , wherein each of the one or more switch devices is configured to store a respective physical forward vector table used to determine the second vector component. 
     
     
         3 . The apparatus as claimed in  claim 2 , wherein the physical forward vector table includes a table select field. 
     
     
         4 . The apparatus as claimed in  claim 2 , wherein the physical forward vector table includes a bit value for each internal output port. 
     
     
         5 . The apparatus as claimed in  claim 4  wherein the bit value determines whether the data frames can be forwarded through an internal output port of the internal output ports. 
     
     
         6 . The apparatus as claimed in  claim 5 , wherein the table select field determines selection of one of associated trunk tables dependent on a destination address of the received frame. 
     
     
         7 . The apparatus as claimed in  claim 1 , wherein each of the one or more switch devices includes a respective flow hash logic used to determine the first vector component, the flow hash logic operable to index a flow hash when the data frame is received dependent on a destination address and a source address included in the header information of the data frame. 
     
     
         8 . The apparatus as claimed in  claim 1 , wherein at least one of the plurality of devices is configured to store a respective echo suppression table used to determine the third vector component. 
     
     
         9 . The apparatus as claimed in  claim 8 , wherein each respective echo suppression table includes group membership information for an associated trunk. 
     
     
         10 . The apparatus as claimed in  claim 8 , wherein each respective echo suppression table includes a bit value for each internal output port. 
     
     
         11 . The apparatus as claimed in  claim 10 , wherein the bit value determines whether the data frame can be forwarded through an internal output port of the internal output ports. 
     
     
         12 . The apparatus as claimed in  claim 1 , wherein the header information comprises an IP network layer header. 
     
     
         13 . The apparatus as claimed in  claim 1 , wherein the forward vector is computed by each of the one or more switch devices. 
     
     
         14 . The apparatus as claimed in  claim 1 , wherein the forward vector selects an internal output port of the internal output ports through which the data frame can be forwarded to a destination. 
     
     
         15 . The apparatus as claimed in  claim 1 , wherein the first vector component comprises a trunk member vector that selects an internal output port of the internal output ports for forwarding the data frame to a destination along with other data frames having similar destination and source addresses. 
     
     
         16 . The apparatus as claimed in  claim 1 , wherein the second vector component comprises a physical forward vector that selects an internal output port of the internal output ports for forwarding the data frame. 
     
     
         17 . The apparatus as claimed in  claim 1 , wherein the third vector component comprises an echo suppression vector that reduces available internal output ports of the internal output ports by ensuring that the data frame is not forwarded through the external port via which the data frame was received. 
     
     
         18 . A network, comprising:
 a multistage switch including:
 i) a plurality of external ports, a first number of the plurality of external ports configured to be coupled to a source of frames; 
 ii) a plurality of devices organized into a plurality rows, each of the rows including a first fan-in/fan-out device, a second fan-in/fan-out device, and one or more switch devices, wherein:
 each device in a row is associated with a different respective stage of a plurality of stages; 
 certain of the devices in a row are connected to each other through internal output ports; 
 the first and second fan-in/fan-out devices are coupled to a number of the plurality of external ports and are configured to receive data frames, each of the data frames being associated with a logical link implemented in the apparatus; and 
 the data frames are communicated on physical paths between one or more of the plurality of devices based on a forward vector determined based on:
 a first vector component determined based at least in part on header information of the received data frame; 
 a second vector component determined based at least in part on a destination address of the received data frame; and 
 a third vector component determined based at least in part on the external port via which the data frame was received; and 
 
 
 a host coupled to a second number of the plurality of external ports of the multistage switch, the host being either a computer, another multistage switch or a router. 
   
     
     
         19 . The network as claimed in  claim 18 , wherein each of the one or more switch devices is configured to store a respective physical forward vector table. 
     
     
         20 . The network as claimed in  claim 18 , wherein the physical forward vector table includes a table select field. 
     
     
         21 . The network as claimed in  claim 20 , wherein the table select field determines selection of one of associated trunk tables dependent on the destination address of the received data frame. 
     
     
         22 . The network as claimed in  claim 18 , wherein each of the one or more switch devices includes a respective flow hash logic used to determine the first vector component, the flow hash logic operable to index a flow hash when the data frame is received dependent on a destination address and a source address included in the header information of the data frame. 
     
     
         23 . The network as claimed in  claim 18 , wherein at least one of the plurality of devices is configured to store a respective echo suppression table used to determine the third vector component. 
     
     
         24 . The network as claimed in  claim 23 , wherein each respective echo suppression table includes group membership information for an associated trunk. 
     
     
         25 . The network as claimed in  claim 18 , wherein the header information comprises an IP network layer header.