Method of modifying packets to a generic format for enabling programmable modifications and an apparatus thereof

A method for a rewrite engine, the method comprising:

• converting each of one or more protocol layers of a header of a packet into a generic format with the rewrite engine, wherein each of the one or more protocol layers is formatted according to one of a plurality of header layer protocols, and further wherein for each one of the one or more protocol layers, the generic format of the one of the protocol layers includes all fields supported by the header layer protocol according to which the one of the protocol layers is formatted;
• maintaining a bit vector for each converted protocol layer with the rewrite engine, wherein the bit vector includes a bit per subsection for each of a plurality of subsections of the converted protocol layer;
• marking each bit of the bit vector based on validity of each subsection of every field of the converted protocol layer with the rewrite engine;
• modifying the converted protocol layer with the rewrite engine;
• and
• updating the bit vector based on the modification of the converted protocol layer with the rewrite engine.

A method for a network switch, the method comprising:

• receiving a packet having a header including a protocol layer at an incoming port of the network switch, wherein the protocol layer is formatted according to a protocol, wherein the protocol supports one or more supported fields;
• generalizing the protocol layer of the header of the packet according to a generic format corresponding to the protocol by adding one or more fields of the supported fields that are missing from the protocol layer to the protocol layer thereby forming a generalized protocol layer;
• modifying the generalized protocol layer by applying at least one command to the generalized protocol layer;
• removing all subsections of the modified protocol layer that were added to form the one or more of the supported fields that were missing to form a new header;
• and
• sending out the packet with the new header via an outgoing port of the network switch.

A method for a network switch, the method comprising:

• configuring the network switch to include software-defined mappings of generic formats of protocols;
• receiving a packet at an incoming port of the network switch, the packet having a header including a protocol layer that is formatted according to one of the protocols;
• generalizing the protocol layer of the packet based on one of the software-defined mappings by adding one or more fields to the protocol layer thereby forming a generalized protocol layer, wherein the one or more fields that are added to the protocol layer are a subset of one or more fields that are supported by the one of the protocols and that were missing from the packet as received;
• and
• maintaining a bit vector for the generalized protocol layer, wherein the bit vector includes a bit per subsection for each of a plurality of subsections of the generalized protocol layer.

A network switch comprising:

• an input port and an output port for receiving and sending packets, wherein each of the packets includes a header having one or more protocol layers and each of the protocol layers is formatted according to one of a plurality of protocols;
• a memory to store a set of software-defined mappings of generic formats of the protocols;
• and
• a rewrite engine that performs a header generalization process on the packets to generalize each of the protocol layers of each of the packets based on the protocol according to which the protocol layer is formatted, wherein the header generalization process comprises expanding each of the protocol layers of each of the packets to a generic size including all fields supported by the protocol according to which the protocol layer is formatted.

A network switch comprising:

• an input port for receiving a packet having a header, wherein the packet includes a body and a plurality of protocol layers that together form a protocol stack, each of the plurality of protocol layers formatted according to one of a plurality of protocols;
• an output port for transmitting modified packets;
• a memory to store a set of software-defined mappings of generic formats of protocols and a set of generic modification commands;
• and
• a rewrite engine to:
• convert each protocol layer of the protocol stack into a generic format based on one from the set of software-defined mappings, wherein the generic format includes all fields supported by the one of the plurality of protocols according to which the protocol layer is formatted;
• maintain a bit vector for each converted protocol layer;
• use the set of generic modifications commands to modify each converted protocol layer;
• update each bit vector after the bit vector is modified to thereby form a new protocol stack;
• and
• attach the new protocol stack with the body to be transmitted via the output port.