This directory includes sample implementations of topology management components:

• Topology daemon is a service that provides topology information for trema apps.

• Topology discovery collects the topology information of OpenFlow switches. Topology discovery uses Link Layer Discovery Protocol (LLDP) to obtain topology information.

                 packet out
             .---------------------------------------.
             v                                       |
    +----------+           +-----------+           +-------+          +----------+
    |  switch  |  *    1   | packet in |  1    *   | trema |  *   1   | topology |
    |  daemon  | --------> |  filter   | --------> | apps  | <------> | daemon   |
    +----------+ packet in +-----------+ packet in +-------+ topology +----------+
      ^ 1    ^                       |                                  ^ 1
      |      |                       |                                  | topology
      |      `-------.               |                                  |
      v 1            |               |                                  v 1
    +----------+     |               |   packet in(LLDP)              +-----------+
    | openflow |     |               `------------------------------->| topology  |
    |  switch  |     `------------------------------------------------| discovery |
    +----------+                         packet out(LLDP)             +-----------+
  

• LLDP is transported over Ethernet by default but it also can be transported over IP.

• show_topology retrieves topology information from the topology daemon and prints it as graph-easy or trema network DSL style.

    $ trema run "./show_topology -G" | graph-easy
  

Please see ../routing_switch/README

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