Exercice spanning tree pdf

Explore Podcasts All podcasts. Difficulty Beginner Intermediate Advanced. Explore Documents. Minimum Spanning Tree. Uploaded by Gomala Mookan. Did you find this document useful? Is this content inappropriate? Report this Document. Flag for inappropriate content. Download now. Related titles. Carousel Previous Carousel Next. A study on Euler graph and Hamiltonian graph 1.

Jump to Page. Search inside document. The network is drawn as a diagram providing a picture of the system, thus enabling visual representation and enhanced understanding. The Minimal Spanning Tree A tree is a graph loops.

The Minimal Spanning Tree Problem Problem: Each node in a network represents a computer in a computer network, arc i,j might represent an underground cable that connects computer i to computer j. STEPS: 1. Select any starting node. Select the node closest to the starting node to join the spanning tree.

Select the closest node not currently in the spanning tree. Repeat step 3 until all nodes have joined the spanning tree. Solution: step 1 Copyright Pearson Education, Inc. Copyright Pearson Education, Inc. Felipe Acevedo. Herhes Cosme. Joao Bravo. Aanya Ralhan. Junaid Mahsud. Ghulam Fareed. Jese Madrid. Sajjad Ahmad. Kidist Talu. Shrest Kumar. Marjorie Nervez Sarino Bongato. Tharshini Suriyakumar. Rekha Bhasin. Cannon Fodder.

More From Gomala Mookan. Gomala Mookan. Port Cost also determines which port will become the root port if multiple paths to the root bridge exist. Default port costs are shown below. Designated Port : The bridges on a network segment collectively determine which bridge has the least-cost path from the network segment to the root. The port connecting this bridge to the network segment is then the designated port for the segment. STP port states are very important.

You should remember these states and what they mean. Each of them is discussed below. None of the ports will transmit or receive any data, but they will listen to BPDUs. The switch does receive the frames but discards them before any action is taken. The switch will start to learn MAC addresses it can see and will populate its CAM table with the addresses and the ports on which they were found.

In this state, the switch will start to transmit its own BPDUs. The switch can now forward traffic. In the Disabled state, the port will receive BPDUs but will not forward them to the switch processor.

It discards all incoming frames from both the port and other forwarding ports on the switch. The port states are transitional and allow other BPDUs to arrive in good time from other switches. Port transition times are typically:. All ports start at the blocking state there are a few exceptions discussed later. After STP convergence, some ports will transition to listening, learning, and finally forwarding while the rest would remain in a blocked state.

Thus the time needed to transition from one stage to another; we find that a layer 2 network running STP takes 50 seconds to start switching data! This is known as the convergence time. Remember that Spanning tree works by selecting a root bridge on the LAN. It is selected by comparing Bridge ID of each switch. Each of the above three steps are discussed in detail below.

The network shown in figure will be used to explain the STP convergence process. The BID consists of two values in an 8-byte field. The bridge priority 32, by default makes up two bytes and the MAC address of the backplane or supervisor module depending upon the model of switch makes up the rest of the six bytes.

The root bridge on a LAN is selected by an election. BPDUs are multicast frames that can be thought of as hello messages between STP enabled switches and they are sent out every two seconds from every port.

This is necessary to maintain a loop free topology. When the switch or bridge priorities combined with its MAC address are all exchanged; the bridge with the lowest ID is selected as the root bridge. All ports on the root bridge are set as designated and thus are always set to a forwarding state.

In our network, the priority of all the switches has been left at the default value. So the switch with the lowest MAC address will be selected the root bridge. In this case it will be SwitchA. Bridge ID Priority priority sys-id-ext 5 Address Interface Role Sts Cost Prio.

In the above output notice that the fourth line states that this bridge is the root bridge. At this stage do not worry about the number 5 used in the command. That is the VLAN id and will be discussed in chapter 7.

Now if we want SwitchC to be the root bridge then we will need to give it better priority using the following command:. For non-root bridges there will be only one root port. The root port will be the port with the lowest path cost to the root bridge. The root port will also be set to forwarding state. Path cost is the cost of transmitting a frame to the root bridge.

The value is set according to the bandwidth of the link on the LAN. The slower the link, the higher the cost is. Remember that a default cost is associated with the bandwidth of a link. The default cost can be seen in table