When this occurs, the port with the lowest port number becomes the root port. Note: In some situations, there may be two ports with equal cost to the root bridge. Neither is it based on the lowest or highest interface identifier values. The root port is not selected based on the first port to receive an STP packet on the root bridge. In some situations, heavy traffic may prevent the reception of BPDUs when the second link is put in place, and in that case, a loop may still form. This helps to ensure that a loop does not form using the redundant connections. STP is enabled by default on Catalyst switches.įor example, if two switches have an active connection between them that is forwarding traffic and a second link is connected between the same two switches, one of the two switch ports will go into a blocking state when BPDUs are received on the link. Rafat Khandaker Packet Tracer Spanning Tree Protocol/PVST / RSTP 05/05/16 ABSTRACT In this Lab simulation, four switches have been set up to separate. Let us try to communicate between two Hosts. As we can see in the above diagram that some light are green while others are orange. Let us develop a basic topology like the one in the following diagram. STP allows the switches to continually explore the network so that the loss or addition of a switch or bridge is also quickly discovered. Spanning Tree Protocol on Packet Tracer Let us apply STP on packet tracer.

An STP-enabled device recognizes a loop in the topology and blocks one or more redundant paths, preventing the loop. Without a loop-avoidance service on the network, Layer 2 devices, in certain situations, will endlessly flood broadcasts. All the ports on the root bridge (the bridge with the lowest bridge ID) are in the forwarding state and are referred to as designated ports.īridges and switches use the Spanning-Tree Protocol (STP) to prevent network loops. The port through which the root bridge can be reached with the lowest-cost path is the root port. FastEthernet0/1 is up, line protocol is up (connected) Hardware is Lance, address is 0001.42bd.5301 (bia 0001.42bd.5301) lower is better so he must select 0001.42bd.5301. Root ports are ports that are in the forwarding state and provide connectivity to the root bridge. why spanning-tree select his bridge mac 00D0.D300.98DB but in the first picture we have lower mac address on FA0/1 which is.

Packet tracer labs spanning tree