evsio0n / epon

Forked Andreas Bontozoglou's EPON implementation from http://sourceforge.net/projects/omneteponmodule/ Ported to work with INET 2.2.

DESCRIPTION

This is a basic implementation of Ethernet Passive Optical Network. OLT and ONU modules are defined and they both support one or multiple LLIDs. MPCP protocol has been implemented on OLT and ONU models to assign LLIDs dynamically. The devices are implemented in a structured way per network Layer and basic goal is to keep them extensible. Different Queue Management, Relay and traffic classification modules should be easily integrated into the existing devices using the same MAC and MAC Control Layers. Since it is under development, many features may be missing.

FEATURES

• MPCP Protocol implementation.

The current implementation varies a bit from the RFCs on the registration process. It currently send the GATE message AFTER the ONU acknowledgment, while the drafts say that the GATE should be sent right after the REGISTER message. This way we avoid allocating resources for an ONU that may not send ACK message later. Actually it just simplifies the upstream bandwidth allocation.

• Layers

MAC: A copy of the inet mac layer with some changes. First it sends messages of type EtherFrameWithLLID, which are actually Ethernet frames but in the preamble they include the LLID. So EPON_PREAMBLE_BYTES is now (7 - 2) and the frame structure is changed. These frames encapsulate the real Ethernet ones. Second, when the interface is IDLE and wakes-up it will wait for IFG time before transmitting (instead of transmitting directly as in the original implementation)

MacCtl Layer: is used to handle time registers on both ONU and OLT. It is also responsible for transmitting to the lower layer at proper time. Currently it seems to work :-) but if you don't want to mess up, try not to touch it... I have spent days in order to achieve the TDMA. IF you see collisions in the Splitter module it means that something went wrong.

Q_mgmt: This module is supposed to do queue management but currently it is not implemented. Bandwidth allocation should be calculated here. This module is extensible and a module interface has been used in the model. So you can replace it with your own module having different functionality.

EPON_Relay: This module implements a switch between MAC interface and PON interface. It takes under consideration the LLIDs on the pon network and the VLANs on the Ethernet one. This module is extensible and a module interface has been used in the model. So you can replace it with your own module having different functionality.

PON_Splitter: Simple passive splitting. On collision, the module discards the second frame while the first one has already been transmitted. Also it counts upstream and downstream collisions. This should actually never happen, but is really useful if you want to change the TDMA functions.

EXTENDING

Some features have been added lately in order to make extending the EPON easier. Now both polling-based and non-polling MacCtl modules are included. For polling setups use the ONUMacCtl_P while for non-polling use the ONUMacCtl_NP (see example .ned files).

For implementing new algorithms, for polling create a new module that will extend the OLTQPerLLiDBase_P class. For non-polling you should extend the OLT_QPL_RR class. IN both cases overriding the DoUpstreamDBA method should be sufficient. More complicated algorithms (like Multi-Tread Polling or Two-Stage DBA) will require more changes (more methods need to be overridden)

For any comments mail me at [email protected]

Andreas