Lockless stateful network address translation

Abstract

Examples include a computing system having a plurality of processing cores and a memory coupled to the plurality of processing cores. The memory has instructions stored thereon that, in response to execution by a selected one of the plurality of processing cores, cause the following actions. The selected processing core to receive a packet and get an original tuple from the packet. When no state information for a packet flow of the packet exists in a state table, select a new network address as a new source address for the packet, get a reverse tuple for a reverse direction, select a port for the packet from an entry in a mapping table based on a hash procedure using the reverse tuple, and save the new network address and selected port. Translate the packet's network address and port and transmit the packet.

What is claimed is: 
     
         1 . A computing system comprising:
 a plurality of processing cores; and   a memory coupled to the plurality of processing cores, the memory having instructions stored thereon that, in response to execution by a selected one of the plurality of processing cores, cause the selected processing core to:   receive a packet;   get an original tuple from the packet;   when no state information for a packet flow of the packet exists in a state table, select a new network address as a new source address for the packet, get a reverse tuple for a reverse direction, select a port for the packet from an entry in a mapping table based on a hash procedure using the reverse tuple, and save the new network address and selected port;   translate the packet's network address and port; and   transmit the packet.   
     
     
         2 . The computing system of  claim 1 , comprising when no state information for the packet flow exists in the state table, set a destination port in the reverse tuple to zero, compute a hash value of the reverse tuple, perform an exclusive-OR (XOR) operation on the hash value of the reverse tuple and a hash value of the original tuple, mask a plurality of the least significant bits (LSBs) of the XOR result to select a port for the packet from an entry in a mapping table based on the masked value, save the new network address and selected port into a state associated with a connection of the packet flow, and insert information describing the packet flow into the state table. 
     
     
         3 . The computing system of  claim 2 , the memory having instructions stored thereon that, in response to execution by the processor, cause the processor to:
 at initialization time, generate the mapping table, the mapping table comprising a plurality of entries, each entry associating a port with a hash value.   
     
     
         4 . The computing system of  claim 2 , the memory having instructions stored thereon that, in response to execution by the processor, cause the processor to:
 create a tuple having a zero value for a source address, a destination address, a source port, and a destination port, select a port, assign a destination port of the tuple to the selected port, compute a hash value of the tuple, mask the hash value with a least significant bits (LSB) mask, and store the port number into the mapping table entry for the selected port.   
     
     
         5 . The computing system of  claim 2 , wherein the selected processing core to receive an original direction packet is the same processing core to transmit a reverse direction packet. 
     
     
         6 . The computing system of  claim 2 , comprising a network input/output (I/O) device, the network I/O device comprising a hash filter redirection table (HFRT), wherein the masked hash value of an original tuple and the masked hash value of a reverse tuple point to a same entry in the HFRT. 
     
     
         7 . The computing system of  claim 6 , the entry in the HFRT indicating a queue in the network I/O device. 
     
     
         8 . A method to be performed by a processor, comprising:
 receiving a packet;   getting an original tuple from the packet;   when no state information for a packet flow of the packet exists in a state table, selecting a new network address as a new source address for the packet, getting a reverse tuple for a reverse direction, selecting a port for the packet from an entry in a mapping table based on a hash procedure using the reverse tuple, and saving the new network address and selected port;   translating the packet's network address and port; and   transmitting the packet.   
     
     
         9 . The method of  claim 8 , comprising: when no state information for the packet flow exists in the state table, setting a destination port in the reverse tuple to zero, computing a hash value of the reverse tuple, performing an exclusive-OR (XOR) operation on the hash value of the reverse tuple and a hash value of the original tuple, masking a plurality of the least significant bits (LSBs) of the XOR result to select a port for the packet from an entry in a mapping table based on the masked value, saving the new network address and selected port into a state associated with a connection of the packet flow, and inserting information describing the packet flow into the state table. 
     
     
         10 . The method of  claim 9 , comprising
 at initialization time, generating the mapping table, the mapping table comprising a plurality of entries, each entry associating a port with a hash value.   
     
     
         11 . The method of  claim 9 , comprising
 creating a tuple having a zero value for a source address, a destination address, a source port, and a destination port, selecting a port, assigning a destination port of the tuple to the selected port, computing a hash value of the tuple, masking the hash value with a least significant bits (LSB) mask, and storing the port number into the mapping table entry for the selected port.   
     
     
         12 . The method of  claim 9 , wherein a selected processing core of a computer system to receive an original direction packet is a same processing core to transmit a reverse direction packet. 
     
     
         13 . The method of  claim 9 , wherein the masked hash value of an original tuple and the masked hash value of a reverse tuple point to a same entry in a hash filter redirection table (HFRT). 
     
     
         14 . The method of  claim 13 , the entry in the HFRT indicating a queue in a network I/O device. 
     
     
         15 . At least one tangible machine-readable medium comprising a plurality of instructions that in response to being executed by a processor cause the processor to:
 receive a packet;   get an original tuple from the packet;   when no state information for a packet flow of the packet exists in a state table, select a new network address as a new source address for the packet, get a reverse tuple for a reverse direction, select a port for the packet from an entry in a mapping table based on a hash procedure using the reverse tuple, and save the new network address and selected port;   translate the packet's network address and port; and   transmit the packet.   
     
     
         16 . The at least one tangible machine-readable medium of  claim 15 , comprising a plurality of instructions that in response to being executed by a processor cause the processor to: when no state information for the packet flow exists in the state table, set a destination port in the reverse tuple to zero, compute a hash value of the reverse tuple, perform an exclusive-OR (XOR) operation on the hash value of the reverse tuple and a hash value of the original tuple, mask a plurality of the least significant bits (LSBs) of the XOR result to select a port for the packet from an entry in a mapping table based on the masked value, save the new network address and selected port into a state associated with a connection of the packet flow, and insert information describing the packet flow into the state table. 
     
     
         17 . The at least one tangible machine-readable medium of  claim 16 , comprising a plurality of instructions that in response to being executed by a processor cause the processor to:
 at initialization time, generate the mapping table, the mapping table comprising a plurality of entries, each entry associating a port with a hash value.   
     
     
         18 . The at least one tangible machine-readable medium of  claim 16  comprising a plurality of instructions that in response to being executed by a processor, cause the processor to:
 create a tuple having a zero value for a source address, a destination address, a source port, and a destination port, select a port, assign a destination port of the tuple to the selected port, compute a hash value of the tuple, mask the hash value with a least significant bits (LSB) mask, and store the port number into the mapping table entry for the selected port. 
 
     
     
         19 . The at least one tangible machine-readable medium of  claim 16 , wherein a selected processing core to receive an original direction packet is a same processing core to transmit a reverse direction packet. 
     
     
         20 . The at least one tangible machine-readable medium of  claim 16 , wherein the masked hash value of an original tuple and the masked hash value of a reverse tuple point to a same entry in a HFRT. 
     
     
         21 . The at least one tangible machine-readable medium of  claim 20 , the entry in the HFRT indicating a queue in a network I/O device.