MMT Protocol Stack

[TOC]

Definition

In MMT, a protocol stack is an abstract concept that defines what ROOT protocol is expected when processing a data packet. We can make a link between a stack and a data link protocol. For example, the Ethernet protocol defines also a stack that starts by Ethernet as a ROOT protocol. Any packet in the Ethernet stack, has Ethernet as ROOT protocol. As the concept of protocol is abstract in MMT, a root protocol does not necessarily need to be a !LinkLayerProtocol (Layer 2 of the OSI model). Rather, any protocol can be associated to a stack.

Internals

A stack must have the following information

An MMT Handler MUST be associated to a protocol stack. When the handler processes a packet, it will first call the classification function of the stack to identify the ROOT protocol.

API

MMT users need not to handle stacks. They only need to indicate the identifier of the stack when creating an MMT Handler.

User API

   mmt_handler_t * mmt_init_handler(uint32_t stacktype, uint32_t options, char * errbuf);

Initializes a new MMT handler with the given stack identifier. Once initialised, a handler can process data packets, register user requests, and notify user upon occurrence of identified events (packet processing, attribute detection, session timeout, etc.).

   int get_data_link_type(mmt_handler_t *mmt_handler);

Returns the data link type of the given mmt handler. The data link type is the identifier of the protocol stack.

Developer API

   int register_protocol_stack(uint32_t s_id, char *s_name, generic_stack_classification_function fct);

   int register_protocol_stack_full(uint32_t s_id, 
      char *s_name, generic_stack_classification_function fct, 
      stack_internal_cleanup stack_cleanup, 
      void * stack_internal_context
    );

Registers a protocol stack given its identifier, name and classification function. In case the stack maintains a local context, the cleanup function needs to be given. The registration fails if a protocol stack is already registered with the given identifier or name.

   int unregister_protocol_stack(uint32_t s_id);

Unregisters a protocol stack given its identifier.

Open Issues