Concatenation of containers in synchronous digital hierarchy network

Abstract

A method of transmitting OSI layer 2 datacoms data by direct incorporation into a plurality of synchronous digital hierarchy virtual containers is disclosed, in which a higher bit rate OSI layer 2 data frame is multiplexed into a plurality of lower bit rate SDH (or SONET) virtual containers, which are transmitted simultaneously and in parallel over a synchronous communications network. The plurality of virtual containers are virtually concatenated by association of the payloads of the plurality of virtual containers. Re-assembly of the OSI layer 2 data frames from a plurality of virtually concatenated VCs is achieved by storing each received VC payload corresponding to an OSI layer 2 data frame in a corresponding respective memory location, and alternately reading interleaved bytes from the plurality of payloads under control of a plurality of read pointers.

1 . A method of transporting data over a synchronous digital network, said method comprising the steps of: 
 generating in parallel a plurality of synchronous virtual containers, each at a lower bit rate than a bit rate of said data, each said virtual container having a payload section;    associating said plurality of virtual containers with each other by means of assigning association data describing said association into said plurality of virtual containers;    inputting said transported data into said payloads of said plurality of virtual containers; and    outputting said plurality of associated virtual containers onto a synchronous digital network.    
   
   
       2 . The method as claimed in  claim 1 , wherein said plurality of associated virtual containers are output onto said synchronous digital network substantially in parallel.  
   
   
       3 . The method as claimed in  claim 1 , wherein said step of associating said plurality of virtual containers with each other comprises inserting said association data into a plurality of payloads of said plurality of virtual containers, said association data permitting recovery of the original association at a destination end.  
   
   
       4 . The method as claimed in  claim 1 , wherein said step of inputting said transported data into said plurality of virtual containers comprises byte interleaving bytes of a frame of said transported data between said plurality of payloads.  
   
   
       5 . The method as claimed in  claim 1 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers with each other comprises associating a plurality of said streams of virtual containers with each other.  
   
   
       6 . The method as claimed in  claim 1 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers, and said step of associating said plurality of virtual containers together by means of assigning association data comprises adding a stream of identification data to each said virtual container, said steam identification data identifying which of said plurality of streams said virtual container belongs to.  
   
   
       7 . The method as claimed in  claim 1 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers together by means of assigning association data comprises including a sequence identification data to individual ones of said plurality of virtual containers, said sequence identification data designating a sequence in which said individual virtual containers are generated with respect to each other.  
   
   
       8 . The method as claimed in  claim 7 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers together by means of assigning association data comprises assigning to individual ones of said plurality of virtual containers a sequence identification data comprising a cyclically repeating code data.  
   
   
       9 . The method as claimed in  claim 1 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers together by means of assigning association data comprises assigning to individual ones of said plurality of virtual containers a cyclically repeating code sequence having a repetition period of at least 2 N+1, where N is the repetition number of sequentially received virtual container payloads in a single stream.  
   
   
       10 . The method as claimed in  claim 1 , wherein the said plurality of virtual containers are generated as a plurality of virtual container streams and said step of associating said plurality of virtual containers together by means of assigning association data comprises utilizing a path trace byte in a virtual container overhead as a stream identifier data for identifying a virtual container as belonging to a particular said virtual container stream.  
   
   
       11 . The method as claimed in  claim 1 , wherein a said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers together by means of assigning association data bytes comprises including a sequence identification data in individual ones of said plurality of virtual containers, said sequence identification data designating a sequence in which said individual virtual container is generated within a said stream of virtual containers, said sequence identification data being carried within a K3 byte of an overhead section of said virtual container.  
   
   
       12 . The method as claimed in  claim 1 , wherein said plurality of virtual containers are generated as a plurality of streams of virtual containers and said step of associating said plurality of virtual containers together by means of assigning association data comprises assigning to individual ones of said plurality of virtual containers a sequence identification data comprising a code data extending over a plurality of said virtual containers of a said stream, for identifying a position of each said virtual container within said virtual container stream.  
   
   
       13 . Apparatus for incorporating data input at a first data rate into a plurality of streams of synchronous digital hierarchy virtual containers each output at a second data rate, said apparatus comprising: 
 means for continuously generating a plurality of virtual containers in parallel;    means for generating data describing an association of said plurality of virtual containers, and for assigning said association data to said plurality of associated virtual containers; and    means for inserting said first data rate data into said plurality of payloads of said plurality of virtual containers.    
   
   
       14 . A method of recovering data from a plurality of synchronous virtual containers, said method comprising the steps of: 
 receiving said plurality of virtual containers;    identifying an association data from said plurality of virtual containers, said association data indicating an association between individual ones of said plurality of virtual containers;    reading data bytes from each payload of said plurality of associated virtual containers; and    re-assembling said data from said plurality of read payload data bytes.    
   
   
       15 . The method as claimed in  claim 14 , wherein said process of reading said data payloads comprises reading a plurality of said payloads in a byte interleaved manner.  
   
   
       16 . The method as claimed in  claim 14 , wherein said step of identifying an association data from each of said plurality of virtual containers comprises reading a plurality of stream identification data from said plurality of virtual containers, said stream identification data designating which of a plurality of streams of virtual containers said virtual containers belong to.  
   
   
       17 . The method as claimed in  claim 14 , wherein said step of identifying an association data between said plurality of virtual containers comprises reading a plurality of sequence identification data designating where in a sequence of virtual containers each individual virtual container belongs.  
   
   
       18 . The method as claimed in  claim 14 , wherein said step of receiving a plurality of said virtual containers comprises receiving a plurality of separate streams of associated virtual containers simultaneously.  
   
   
       19 . The method as claimed in  claim 14 , wherein said step of reading data bytes from each payload of said plurality of associated virtual containers comprises reading said data bytes substantially in parallel from a plurality of virtual containers of a same sequence identification from a plurality of associated virtual container streams.  
   
   
       20 . The method as claimed in  claim 14 , wherein said step of receiving a plurality of said virtual containers comprises receiving a plurality of separate streams of associated virtual containers, and said step of identifying an association data from said plurality of virtual containers comprises inspecting a path trace byte of each of a plurality of said virtual containers, and distinguishing from which of a set of said streams of virtual containers said individual virtual containers belong, from said read path trace data bytes.