On Fri, 4 Sep 2020 09:15:20 +
Henrik Bjoernlund wrote:
> Connectivity Fault Management (CFM) is defined in 802.1Q section 12.14.
>
> Connectivity Fault Management (CFM) comprises capabilities for
> detecting, verifying, and isolating connectivity failures in
> Virtual Bridged Networks. These capabilities can be used in
> networks operated by multiple independent organizations, each
> with restricted management access to each other’s equipment.
>
> CFM functions are partitioned as follows:
> — Path discovery
> — Fault detection
> — Fault verification and isolation
> — Fault notification
> — Fault recovery
>
> The primary CFM protocol shims are called Maintenance Points (MPs).
> A MP can be either a MEP or a MHF.
> The MEP:
> -It is the Maintenance association End Point
> described in 802.1Q section 19.2.
> -It is created on a specific level (1-7) and is assuring
> that no CFM frames are passing through this MEP on lower levels.
> -It initiates and terminates/validates CFM frames on its level.
> -It can only exist on a port that is related to a bridge.
> The MHF:
> -It is the Maintenance Domain Intermediate Point
> (MIP) Half Function (MHF) described in 802.1Q section 19.3.
> -It is created on a specific level (1-7).
> -It is extracting/injecting certain CFM frame on this level.
> -It can only exist on a port that is related to a bridge.
> -Currently not supported.
>
> There are defined the following CFM protocol functions:
> -Continuity Check
> -Loopback. Currently not supported.
> -Linktrace. Currently not supported.
>
> This CFM component supports create/delete of MEP instances and
> configuration of the different CFM protocols. Also status information
> can be fetched and delivered through notification due to defect status
> change.
>
> The user interacts with CFM using the 'cfm' user space client program, the
> client talks with the kernel using netlink. The kernel will try to offload
> the requests to the HW via switchdev API (not implemented yet).
>
> Any notification emitted by CFM from the kernel can be monitored in user
> space by starting 'cfm_server' program.
>
> Currently this 'cfm' and 'cfm_server' programs are standalone placed in a
> cfm repository https://github.com/microchip-ung/cfm but it is considered
> to integrate this into 'iproute2'.
>
> Reviewed-by: Horatiu Vultur
> Signed-off-by: Henrik Bjoernlund
Could this be done in userspace? It is a control plane protocol.
Could it be done by using eBPF?
Adding more code in bridge impacts a large number of users of Linux distros.
It creates bloat and potential security vulnerabilities.
