Method and device for checking connectivity in TRILL (Transparent Interconnection of Lots of Links) network

The invention discloses a method for checking the connectivity in a TRILL (Transparent Interconnection of Lots of Links) network. Any one multicast tree in the TRILL network comprises a plurality of RB (Radio Bear). The method comprises the following steps of: determining whether a unicast routing table entry from an RB to a multicast tree root of the multicast tree exists in a local unicast routing table entry by any RB, if so, determining a link between the RB and the multicast tree root to be reachable; and if not, determining the link between the RB and the multicast tree root to be not reachable. Based on the same invention conception, the invention also provides a device which can be used for quickly detecting whether the link is reachable under the condition of not increasing interactive messages.