Bridge ID is the combination of Bridge Priority(32768) and Switch base MAC address.By default 32768 is the priority in all cisco Switches.ĭesignated Port: Designated port of the switch will be in the forwarding state.All ports of the Root Switch will be designated port. Terms Using by Spanning Tree Protocol BPDU : Bridge Protocol Data Units contains the information of the Switches to use in the root switch selection process.When switch starts the spanning tree is used to find the root switch.BPDU will be sent to all devices in network with BID.īridge ID BID : STP tracks all switches in switched network. Learning port learns all path in a Switched network by using received Bridge Protocol Data Units (BPDU).Learning state generates the MAC address table, but it won't forward the data frames.įorwarding port sends and receives all the data frames.Forwarding port will be either designated or Root port.ĭisabled port is administratively disabled, it won't participate in this process, Listening port will listen to Bridge Protocol Data Units (BPDU) to make sure there is no loops in the network.Listenting port prepares frames to foward but it won't populate the MAC address table. So, multiple links are very important.Īt the same time multiple links often cause many problems in the network, Switches forwards and receives same frames again and again in a looped network and it will take entire bandwidth and it makes the network unstable, and there will be a problem in maintaing stable MAC address table.STP is uses Spanning Tree Algorithm (SPA) to construct the loop free network.ĭefault Spanning Tree Timers Blocked Port (Loss of BPDU) Max Age = 20 secīy deafault, All the ports are in blocking state when the switch starts,Blocking ports just listen to Bridge Protocol Data Units (BPDU).Looped path will be in blocking state, if any links fails the STP recalculate the paths. Redundant links between layer 2 devices are very important in the network,it prevents total network failure.Single link between devices fails, there will be network failure. Spanning Tree Protocol (STP) presents in layer 2 Switches and Bridges to keep the network loop free,Its IEEE Standard is IEEE 802.1D. Understanding Spanning Tree Protocol (STP) in Packet Tracer with Simple topology using 2950-24 Switch.

Packet tracer labs spanning tree