README.L2fwd.org

L2 Packet Forwarding (L2fwd)

The L2 Packet Forwarding pipeline (name: L2fwd) models a simple Ethernet switch using a static MAC lookup table. Note that this pipeline is rather basic and it will not perform MAC learning or L3 routing. (Contributions are welcome!)

Static pipeline

Upstream the L2fwd pipeline will receive packets from the downlink port, perform a lookup for the destination MAC address in a static MAC table, and if a match is found the packet will be forwarded to the uplink port or otherwise dropped (or likewise forwarded upstream if the fakedrop parameter is set to true). The downstream pipeline is just the other way around, but note that the upstream and downstream pipelines use separate MAC tables.

Dynamic scenarios

The L2fwd pipeline defines a single dynamic scenario:

• table-update: models a L2 MAC table update, whereby a MAC table entry is added to/removed from the upstream and downstream MAC tables

Pipeline configuration

A sample TIPSY configuration for the L2fwd pipeline is shown below:

{
    "pipeline": {
         "name": "L2fwd",
         "upstream-table-size": 100000,
         "downstream-table-size": 20, 
         "fluct-table": 30,
         "fakedrop": false
    }
}

The parameters specific to the L2fwd pipeline are as follows:

• name: name of the pipeline, must be set to l2fwd for the L2fwd pipeline
• upstream-table-size: number of entries in the upstream MAC table
• downstream-table-size: number of entries in the downstream MAC table
• fluct-table: number of MAC table entry update events (table-update) per sec
• fakedrop: whether to actually drop unmatched packets (false) or send them immediately to the output port (false) for correct rate measurements

OVS Implementation: Caveats and considerations

BESS Implementation: Caveats and considerations