Connectivity Fault Management(CFM)

Connectivity Fault Management (CFM) is defined in 802.1Q section 12.14. The primary CFM protocol shims are called Maintenance Points (MPs). A MP can be either a MEP or a MHF. Currently only MEP is supported.

CFM

This application is used to configure the kernel via netlink interface to implement CFM protocols and listening on CFM kernel notifications. This is the first proposal of implementing a subset of the standard. It supports only untagged port Down-MEP and only the CCM functionallity.

Dependencies

It depends on the following libs Linux 5.8, 'libnl', 'libev' and 'libmnl'

Build

mkdir build
cd build
cmake ..
make -j12

Usage

If you want CFM notifications from kernel to print status the CFM server must be started. Using the command

cfm_server &

If the kernel doesn’t support CFM, then the server will print an error message and will exit. It is required for the kernel to be compiled with the config CONFIG_BRIDGE_CFM.

Before configuring any MEP instance on a port it is required to create a bridge and add the port to the bridge.

ip link set dev eth0 up
ip link set dev eth1 up
ip link set dev eth2 up
ip link set dev eth3 up
ip link add name br0 type bridge
ip link set dev eth0 master br0
ip link set dev eth1 master br0
ip link set dev eth2 master br0
ip link set dev eth3 master br0
ip link set dev br0 up

Now that the bridge is created, it is possible to add an MEP instance to the bridge. The client will communicate with the kernel via netlink interface.

Create a MEP instance:

    cfm mep-create bridge <bridge> instance <instance> domain <domain> direction <direction>  port <port>
    bridge: br0 instance: 1 domain: port direction: down port: eth0

Delete a MEP instance:

    cfm mep-delete bridge <bridge> instance <instance>
    bridge: br0 instance: 1

Configure a MEP instance:

    cfm mep-config bridge <bridge> instance <instance> mac <mac> level <level> mepid <mepid>
    bridge: br0 instance: 1 mac: 00:00:00:00:00:11 level: 7 mepid: 10

Configure the CC protocol:

    cfm cc-config bridge <bridge> instance <instance> enable <enable> interval <interval> maid-name <name>
    bridge: br0 instance: 1 enable 1 interval: 1s maid-name: ABCDEFGHIJ

Configure adding a peer MEP:

    cfm cc-peer bridge <bridge> instance <instance> remove <remove> mepid <mepid>
    bridge: br0 instance: 1 remove 0 mepid: 8

Configure transmission of CCM frames:

    cfm cc-ccm-tx bridge <bridge> instance <instance> dmac <dmac> sequence <sequence> period <period>
                  iftlv <iftlv> iftlv-value <iftlv-value>
                  porttlv <porttlv> porttlv-value <porttlv-value>
    bridge: br0 instance: 1 dmac 00:00:00:00:00:22 sequence: 1 period: 10 iftlv: 1 iftlv-value: 100 porttlv: 1 porttlv-value: 200

Configure the RDI to insert in transmission of CCM frames:

    cfm cc-rdi bridge <bridge> instance <instance> rdi <rdi>
    bridge: br0 instance: 1 rdi 1

Show the CFM MEP configuration:

    cfm mep-config-show bridge <bridge>"
    bridge: br0

Show the CFM MEP status:

    cfm mep-status-show bridge <bridge>"
    bridge: br0