erlang-lldp
About
This package implements LLDP protocol. It can be included as a library or as a standalone application. It exposes a behavior gen_lldp that can be included in projects where user can provide custom interfaces to their operating system or their use case. For example, this can be used in Erlang based OpenFlow Controller(originally from FlowForwarding/loom) loom to discover topology.
How to use
Standalone App
Development and test environment is captured in docker-compose.yml
| Name | What is this |
|---|---|
| lldp | Docker for compiling running erlang-lldp code |
| lldp1 | Linux Docker container connected to lldp
|
| lldp2 | Linux Docker container connected to lldp
|
$ make up # Bring up development and test environment
$ make. # Compile the code
$ make run # Run the application
Now from Erlang shell one can do the following to display local interface information and discovered neighbors information
(lldp@lldp)10> lldp_manager:dashboard(lldp_netlink).
-------- ------------------ ------------ ------------ ------------------ ---- ---------- ----------
IfName Chassis Id Port Id System Name Mgmt Address Nbrs Rx Pkts Tx Pkts
-------- ------------------ ------------ ------------ ------------------ ---- ---------- ----------
eth2 02:42:0A:00:7B:0A eth2 lldp 10.0.101.1 1 11 15
eth1 02:42:0A:00:7B:0A eth1 lldp 10.0.100.1 1 11 15
------------------ ------------------ --- ------------ ------------------ ------------------
Chassis Id Port Id Ttl System Name Mgmt Info Expires At
------------------ ------------------ --- ------------ ------------------ ------------------
02:42:0A:00:7B:1E 02:42:0A:00:65:02 120 lldp2 10.0.123.30 4/23/2019 6:08pm
02:42:0A:00:7B:14 02:42:0A:00:64:02 120 lldp1 10.0.123.20 4/23/2019 6:08pm
As a library
Include the library as a rebar lldp from hex dependency as follows:
{deps, [
lldp
]}. 
erlang-lldp can be adapted to be used on a custom platform as well. Platform specific information can be captured in an Erlang module by following gen_lldp behavior. It is expected to support the following callback functions by the custom module.
| Callback | Description |
|---|---|
| init | Initialization function which can be used to relay platform specific state variable |
| handle_message | Typical message like tx_packet to transmit packet, or started to indicate, module is to be initialized and hence populate interface information, etc |
| notify | Notifications like, neighbor has been added/deleted/updated |
| info | Platform specific information that needs to be plumbed through lldp_mamager:info calls |
| terminate | LLDP module is being shutdown |
