Fabric Attach (FA) extends the fabric edge to devices that do not support Shortest Path Bridging MAC (SPBM). With FA, non-SPBM devices can take advantage of full SPBM support, when support is available.
FA also decreases the configuration requirements on SPBM devices by off-loading some configuration to the attached non-SPBM devices and by automating certain configuration steps that occur most often.
The FA elements communicate between themselves using FA Signaling. FA Signaling is an application level protocol that leverages standard network protocols, such as LLDP, to exchange messages and data between FA elements to orchestrate network automation.
FA Server—An SPB capable network device connected to the fabric edge running the FA agent in FA Server mode. FA Servers receive requests to create services with specific I-SID/VLAN bindings.
In the SPBM architecture an FA Server is a BEB. FA servers process requests for service creation from FA Proxy and/or FA Clients.
FA Proxy—A device running the FA agent in FA Proxy mode.
An FA Proxy device may or may not be capable of running SPB. SPB is always disabled on devices running FA Proxy. FA Proxy mode is enabled by default on devices supporting this mode.
FA Proxies support I-SID/VLAN assignment definition and have the ability to advertise these assignments for possible use by an FA Server, if connectivity permits.
FA Client—A non-SPB network attached device running the FA agent in FA Client mode and able to advertise ISID/VLAN binding requests for service creation to an FA Proxy or FA Server. Non-FA clients without an FA agent are supported through the FA EAP support.
FA Standalone Proxy–An FA device running the FA agent in FA Standalone Proxy mode. FA Standalone Proxy supports FA Proxy functionality in environments without an FA Server.
An FA Standalone Proxy can be used to automate the configuration of traditional VLANs for devices connected to it, such as WLAN Access Points.
The FA Standalone Proxy does not send provisioning requests upstream. An FA Standalone Proxy automatically accepts requests from FA clients and assumes that the upstream network has been provisioned appropriately.
FA Standalone Proxy can be used in environments where the devices upstream from the FA Standalone Proxy do not support Fabric Attach, but the devices downstream from it support Fabric Attach.
The ISW only performs the functions of an FA Client.
Note
Extreme WLAN Access Points and Defender for IOT are FA Clients which initiate Fabric Attach VLAN/I-SID bindings themselves. If these are connected to an ISW, they will not be able to perform Fabric Attach VLAN/I-SID signaling because the ISW FA Client does not implement the proxy function of an FA Proxy.