Positive feedback ethernet link flow control for promoting lossless ethernet

Abstract

An Ethernet node includes a receiver and transmitter for coupling to an Ethernet link for transceiving Ethernet frames with a remote Ethernet node at a remote end of the Ethernet link. The Ethernet node sends to the remote Ethernet node credit information that enables the remote Ethernet node to know an amount of Ethernet frames the remote Ethernet node is allowed to send to the Ethernet node. The credit information may be specified on a VLAN priority basis and may be included in a header piggy-backed on a host Ethernet frame or may be included in an explicit frame. The credit information may incrementally replenish credits or may specify an absolute credit amount and may be sent in response to processing frames, detection of a frame error, receipt of a request from the remote node or other events.

I Claim: 
     
         1 - 20 . (canceled) 
     
     
         21 . An Ethernet node, comprising:
 a receiver for coupling to an Ethernet link for receiving Ethernet frames from a remote Ethernet node on the Ethernet link; and   a transmitter for coupling to the Ethernet link for sending Ethernet frames to the remote Ethernet node on the Ethernet link;   wherein:
 the Ethernet node is operable to send to the remote Ethernet node credit information; 
 said credit information specifies one or more virtual local area network (VLAN) priorities; and 
 said credit information enables the remote Ethernet node to determine an amount of Ethernet frames corresponding to each VLAN priority that the remote Ethernet node is allowed to send to the Ethernet node. 
   
     
     
         22 . The Ethernet node of  claim 21 , wherein the credit information instructs the remote Ethernet node to increase a credit count by a number of frame quanta indicated in the credit information. 
     
     
         23 . The Ethernet node of  claim 21 , wherein the credit information instructs the remote Ethernet node to re-establish a credit count based on a number of frame quanta indicated in the credit information. 
     
     
         24 . The Ethernet node of  claim 21 , wherein the Ethernet node is operable to send the credit information in response to a request for the credit information by the remote Ethernet node. 
     
     
         25 . The Ethernet node of  claim 21 , wherein the credit information is included in a header piggy-backed on a host Ethernet frame that includes a payload for an upper layer protocol above the Ethernet data link layer protocol. 
     
     
         26 . The Ethernet node of  claim 25 , wherein:
 the header comprises an EtherType field that specifies a predetermined value to indicate that the header includes the credit information;   the predetermined value of the EtherType field is distinct from a value in a succeeding EtherType field of the host Ethernet frame that is not within the header; and   the value in the succeeding EtherType field specifies the upper layer protocol.   
     
     
         27 . The Ethernet node of  claim 25 , wherein:
 the host Ethernet frame comprises a virtual local area network (VLAN) priority tag that specifies a VLAN priority; and   the credit information enables the remote Ethernet node to determine the amount of Ethernet frames corresponding to the specified VLAN priority that the remote Ethernet node is allowed to send to the Ethernet node.   
     
     
         28 . The Ethernet node of  claim 21 , wherein the Ethernet node is operable to send the credit information in response to the Ethernet node processing Ethernet frames received from the remote Ethernet node. 
     
     
         29 . The Ethernet node of  claim 21 , wherein the Ethernet node is operable to receive from the remote Ethernet node second credit information that enables the Ethernet node to determine an amount of Ethernet frames the Ethernet node is allowed to send to the remote Ethernet node. 
     
     
         30 . A method comprising:
 sending, by a first Ethernet node, to a second Ethernet node first credit information that enables the second Ethernet node to determine a first amount of Ethernet frames the second Ethernet node is allowed to send to the first Ethernet node; and   receiving, by the first Ethernet node, from the second Ethernet node second credit information that enables the first Ethernet node to determine a second amount of Ethernet frames the first Ethernet node is allowed to send to the second Ethernet node;   wherein:
 the Ethernet frames are communicated on an Ethernet link that couples the first Ethernet node and the second Ethernet node; 
 one or both of said first credit information and said second credit information specifies one or more virtual local area network (VLAN) priorities; and 
 said one or both of said first credit information and said second credit information enables a respective receiving node to determine an amount of Ethernet frames corresponding to each VLAN priority that the respective receiving node is allowed to send to a respective sending node. 
   
     
     
         31 . The method of  claim 30 , further comprising:
 increasing, by the second Ethernet node, a first credit count by a number of frame quanta indicated in the first credit information; and   increasing, by the first Ethernet node, a second credit count by a number of frame quanta indicated in the second credit information.   
     
     
         32 . The method of  claim 30 , wherein one or both of said first credit information and said second credit information instructs a respective receiving node to re-establish a credit count based on a number of frame quanta indicated in the at least one of said first credit information and said second credit information. 
     
     
         33 . The method of  claim 30 , wherein one or both of said first credit information and said second credit information is included in a header piggy-backed on a host Ethernet frame that includes a payload for an upper layer protocol above the Ethernet data link layer protocol. 
     
     
         34 . The method of  claim 33 , wherein:
 the header comprises an EtherType field that specifies a predetermined value to indicate that the header includes the credit information;   the predetermined value of the EtherType field is distinct from a value in a succeeding EtherType field of the host Ethernet frame that is not within the header; and   the value in the succeeding EtherType field specifies the upper layer protocol.   
     
     
         35 . The method of  claim 33 , wherein:
 the host Ethernet frame comprises a virtual local area network (VLAN) priority tag that specifies a VLAN priority; and   the credit information enables the respective receiving node to determine the amount of Ethernet frames corresponding to the specified VLAN priority that the respective receiving node is allowed to send to the respective sending node.   
     
     
         36 . The method of  claim 30 , further comprising:
 sending, by the first Ethernet node, the first credit information in response to the first Ethernet node processing Ethernet frames received from the second Ethernet node; and   sending, by the second Ethernet node, the second credit information in response to the second Ethernet node processing Ethernet frames received from the first Ethernet node.   
     
     
         37 . The method of  claim 30 , comprising sending, by the first Ethernet node, the first credit information in response to detecting an error in an Ethernet frame received on the link by the first Ethernet node. 
     
     
         38 . An Ethernet node, comprising:
 a receiver for coupling to an Ethernet link for receiving Ethernet frames from a remote Ethernet node on the Ethernet link; and   a transmitter for coupling to the Ethernet link for sending Ethernet frames to the remote Ethernet node on the Ethernet link;   wherein the Ethernet node is operable to:
 receive from the remote Ethernet node credit information, said credit information specifying one or more virtual local area network (VLAN) priorities; and 
 determine based on said credit information, an amount of Ethernet frames corresponding to each VLAN priority that the Ethernet node is allowed to send to the remote Ethernet node. 
   
     
     
         39 . The Ethernet node of  claim 38 , wherein the Ethernet node is operable to increase a credit count based on a number of frame quanta indicated in the credit information. 
     
     
         40 . The Ethernet node of  claim 38 , wherein Ethernet node is operable to re-establish a credit count based on a number of frame quanta indicated in the credit information. 
     
     
         41 . The Ethernet node of  claim 38 , wherein Ethernet node is operable to send a request for the credit information to the remote Ethernet node. 
     
     
         42 . The Ethernet node of  claim 38 , wherein the Ethernet node is operable to send to the remote Ethernet node second credit information that enables the remote Ethernet node to determine an amount of Ethernet frames the remote Ethernet node is allowed to send to the Ethernet node.