200 301 ccna book todd lammle

200 301 ccna book todd lammle.If the priority part of the BID is the same, the switch with the lowest MAC address in the BID is used as the root switch. Because the second part of the BID is the burn-in MAC address of the switch, it can also be used for comparison. For example, if the priority part of the BID is the same and the MAC address in the BID of one of the switches is 0020.0000.0000,and the MAC address in the other switch is 0911.1111.1111,then the first switch (MAC address 0020.0000.0000) is used as the root switch.STP elects the root switch in this way: first, all switches issue HelloBPDUs and declare themselves as the root, with their own BID listed in the BPDU and serving as the root BID; at this point, if a switch receives a Hello message with a better (smaller) BID recorded in the message, that switch immediately stops announcing itself as the root and starts forwarding Advanced Hell. message; the Hello message sent by the better switch lists the better BID and acts as the root; this process is analogous to a political campaign, where the candidate with the lower support rating drops out of the race and supports another candidate instead. Finally, the switches all unanimously agree and support the elected switch with the optimal (minimum) BID, and this concludes the process of simulating a political campaign.Hint: A good greeting, i.e., a good (small number) listed root BID, is called an excellent greeting; a poor greeting, i.e., a bad (large number) listed root BID, is called an inferior greeting.Figure 1-5 shows the beginning of the root switch election process. As shown in the figure, SW1 first announces itself as the root, and SW2 and SW3 perform similar announcements. However, SW2 will consider SW1 to be the superior root, and SW2 begins forwarding Hello messages from SW1. At this point, the diagram shows that SW1 sends a Hello message listing SW1 as the root; SW2 agrees with this and forwards SW1's Hello, which lists SW1 as the root but SW3 still considers itself to be optimal, so it still lists SW3's BID as the root BID in the HelloBPDU.Overhead to root: 0 my BID:32769:0200.0001.0001 root BID: 32769:0200.0001.0001As shown in Figure 1-5, there are two more candidate switches: SW1 and SW3. who will win? According to the BID, the switch with the lower priority will win, and if the priority is the same, the switch with the smaller MAC address will win. As shown in Figure 1-5, SW1's BID (32769:0200.0000.0001) is smaller than SW3's BID (32769:0200.0003.0003), so SW1 wins, and SW3 now considers SW1 to be the superior switch. Figure 1-6 shows the final Hello message sent by the switch.14 Chapter 1 Defining the Spanning Tree ProtocolOverhead to root: 0 my BID: 32769:0200.0001.0001 ft:32769:0200.0001.0001Figure 1-6 SW1 wins the election After the election is complete, only the root switch can continue to send the original STP HelloBPDU message. The other switches receive only the Hello message, update the sender's BID field (and the overhead field to the root), and finally forward this Hello message outward through the other interfaces. Figure 1-6 reflects the process as follows: step 1 SW1 sends a Hello message; step 2, SW2 and SW3 each forward this Hello message outward independently through other interfaces. In summary, each switch claims to be the root switch, and the switch with the lowest numerical BID wins. The BIDs are divided into multiple parts and compared: /gilj. the smallest BID1. rhombus point If the BIDs have the same priority. the smallest switch MAC address wins Selecting the Root Port for Each Switch The second part of the STP process is to select one and only one root port (Root Port) for each non-root switch. A switch's root port (RP) is the interface with the lowest STP overhead from that switch to the root switch (minimum root overhead).