Efficient parsing of extended packet headers

Communication apparatus, comprising:

• multiple interfaces configured to be connected to a network so as to receive and transmit data packets having respective packet headers, wherein at least some of the data packets have a packet header that includes at least first and second sub-headers of different, respective types selected from among a set of predefined types, and the first sub-header contains a field defining a type of the second sub-header;
• a memory configured to store:
• configuration files each including instructions for parsing a respective one of the predefined types of sub-headers, wherein at least some of the configuration files include an alias name of a group of a plurality of types to which the type of the configuration file belongs, and
• a transition table of entries, in which each entry correlates between a pair of a current sub-header type and a subsequent sub-header type and a corresponding location of one of the configuration files which includes instructions for parsing a sub-header corresponding to the entry, wherein the current sub-header type of at least some of the entries in the transition table identify a group of a plurality of different predefined types by a single common alias, such that the single common alias refers to a plurality of different predefined types;
• and
• routing logic, which is configured, upon receiving a packet of the at least some of the data packets, to parse the first sub-header of the received packet, to read the type of the second sub-header from the first sub-header, to retrieve the single common alias of the group of types to which the first sub-header belongs from the configuration file corresponding to the type of the first sub-header, to access the transition table using the retrieved single common alias and the type of the second sub-header so as to locate and read the instructions in the configuration file for parsing the second sub-header, to parse the second sub-header using the instructions, and to process and forward the data packets via the interfaces to the network based on information extracted from the parsed sub-headers.