Methods for dynamic bandwidth allocation and queue management in ethernet passive optical networks

Abstract

In a passive optical network, dynamic bandwidth allocation and queue management methods and algorithms, designed to avoid fragmentation loss, guarantee that a length of a grant issued by an OLT will match precisely the count of bytes to be transmitted by an ONU. The methods include determining an ONU uplink transmission egress order based on a three-stage test, and various embodiments of methods for ONU report threshold setting.

What is claimed is: 
     
         1 . A method for transmitting packets by an optical network unit (ONU) in a passive optical network (PON), comprising the steps of: whenever receiving a grant having a grant length from an optical line terminal (OLT) of the PON:
 a) calculating an ONU packet egress order based on the grant length; and   b) selecting a set of at least one packet whose total length equals the grant length, according to said calculated ONU packet egress order, without fragmenting any of the at least one packet; and   c) transmitting said set.   
     
     
         2 . The method of  claim 1 , wherein the step of calculating is preceded by a step of handling out of band information, and includes handling a sub-queue of a given priority. 
     
     
         3 . The method of  claim 2 , wherein the handling includes checking the sub-queue for ungranted packets, and wherein the step of calculating includes performing a three-stage test on each of the ungranted packets, each of the stage tests involving a stage variable. 
     
     
         4 . The method of  claim 3 , wherein the stage variable is selected from the group consisting of reported bytes below threshold, reported total bytes, and total bytes, and wherein the performing of a stage test involving a stage variable includes comparing a value of the stage variable to zero. 
     
     
         5 . The method of  claim 4 , wherein the ungranted packet is marked as granted if the result of the comparison is that the value of the stage variable is greater than zero. 
     
     
         6 . The method of  claim 1 , wherein the grant is a flexible grant set by the OLT based on information received from the ONU. 
     
     
         7 . The method of  claim 6 , wherein the information includes a combination of values of bytes below threshold and values of total bytes. 
     
     
         8 . The method of  claim 7 , wherein the threshold is adaptive. 
     
     
         9 . The method of  claim 7 , wherein the values of bytes below threshold and the values of total bytes are accumulated from highest to lowest priority. 
     
     
         10 . The method of  claim 1 , wherein said set includes a plurality of said packets.