Chapter 5 - Spanning Tree Protocol Chapter 5 Spanning Tree Protocol CCNA Exploration 4.0 Objectives • Explain the role of redundancy in a converged network network . • Summarize how STP works to eliminate Layer 2 loo p s in a conver g ed network. pg • Explain how the STP algorithm uses three steps to converge on a loop-free topology. • Implement rapid PVST+ in a LAN to prevent loops between redundant switches. Học viện mạng Bách Khoa - Website: www.bkacad.com 2 Layer 2 redundancy Học viện mạng Bách Khoa - Website: www.bkacad.com 3 Redundancy in a hierarchical network • Layer 2 redundancy improves the availability of the network by implementing alternate network paths by adding equipment and cabling. cabling. Học viện mạng Bách Khoa - Website: www.bkacad.com 4 Examine a redundant design • In a hierarchical design, redundancy is achieved at the distribution and core layers through additional hardware and alternate paths through the additional hardware the additional hardware . Học viện mạng Bách Khoa - Website: www.bkacad.com 5 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com 6 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com 7 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com 8 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com 9 Types of Traffic Uk Ui T yp es of traffic ( La y er 2 p ers p ective ) U n k nown U n i cast yp ( y p p ) • Known Unicast: Destination addresses are in Switch Tables • Unknown Unicast: Destination addresses are not in Switch Tables • Multicast: Traffic sent to a g rou p of addresses Học viện mạng Bách Khoa - Website: www.bkacad.com 10 gp • Broadcast: Traffic forwarded out all interfaces except incoming interface. [...]... mạng Bách Khoa - Website: www.bkacad.com 17 Real-world Redundancy Issues Loops in the Cubicles Học viện mạng Bách Khoa - Website: www.bkacad.com 18 Prevent loop, storm bordcast…? • • Block redundant link and auto unblock redundant link when primary link down Via Spanning Tree Protocol Học viện mạng Bách Khoa - Website: www.bkacad.com 19 Spanning Tree Protocol p g Học viện mạng Bách Khoa - Website: www.bkacad.com... the network Non-designated ports - All ports configured to be in a blocking state to prevent loops • Học viện mạng Bách Khoa - Website: www.bkacad.com 23 The Root Bridge • Every spanning- tree instance (switched LAN or broadcast domain) has a switch designated as the root bridge The root bridge serves as a reference point for all spanning tree calculations to determine which spanning- tree redundant... failure, STP recalculates the paths and unblocks the necessary ports to allow the redundant path to become active active Học viện mạng Bách Khoa - Website: www.bkacad.com 21 Spanning- Tree Protocol • • • • Layer 2 protocol STP executes an algorithm called Spanning Tree Algorithm (STA) (STA) STA chooses a reference point, called a root bridge, and then determines the available paths to that reference point... Khoa - Website: www.bkacad.com 25 Bridge ID (BID) Priority-based decision Học viện mạng Bách Khoa - Website: www.bkacad.com 26 Bridge ID (BID) Priority-based decision Học viện mạng Bách Khoa - Website: www.bkacad.com 27 Bridge ID (BID) Configure and Verify the BID Học viện mạng Bách Khoa - Website: www.bkacad.com 28 Best Paths to the Root Bridge • When the root bridge has been designated for the spanning- tree. .. creating a loop-free topology: – Bridge ID – Path Cost Học viện mạng Bách Khoa - Website: www.bkacad.com 22 STP Algorithm • STP uses the Spanning Tree Algorithm (STA) to determine which switch ports on a network need to be configured for blocking to prevent loops from occurring • • • Root Bridge – The lowest BID Root Ports - Switch ports closest to the root bridge Designated ports - All non-root ports... BPDU The BPDU Process Học viện mạng Bách Khoa - Website: www.bkacad.com 32 STP BPDU The BPDU Process Học viện mạng Bách Khoa - Website: www.bkacad.com 33 STP BPDU The BPDU Process Học viện mạng Bách Khoa - Website: www.bkacad.com 34 STP BPDU The BPDU Process Học viện mạng Bách Khoa - Website: www.bkacad.com 35 STP BPDU The BPDU Process Học viện mạng Bách Khoa - Website: www.bkacad.com 36 ... has been designated for the spanning- tree instance, the STA starts the process of determining the best paths to the root bridge from all destinations in the broadcast domain Học viện mạng Bách Khoa - Website: www.bkacad.com 29 Best Paths to the Root Bridge Example Học viện mạng Bách Khoa - Website: www.bkacad.com 30 STP BPDU • The BPDU Fields Học viện mạng Bách Khoa - Website: www.bkacad.com 31 STP BPDU... sent onto a looped network can result in duplicate frames arriving at the destination device Học viện mạng Bách Khoa - Website: www.bkacad.com 15 Issues with Redundancy • Incorrectly learn the MAC address Học viện mạng Bách Khoa - Website: www.bkacad.com 16 Real-world Redundancy Issues Loops in the Wiring Closet • If the network cables are not properly labeled when they are terminated in th i the patch... Khoa - Website: www.bkacad.com 13 Broadcast Storms • A broadcast storm occurs when there are so many broadcast frames caught in a Layer 2 loop that all available bandwidth is consumed Học viện mạng Bách Khoa - Website: www.bkacad.com 14 Duplicate Unicast Frames • Unicast frames sent onto a looped network can result in duplicate frames arriving at the destination device Học viện mạng Bách Khoa - Website:...Issues with Redundancy Học viện mạng Bách Khoa - Website: www.bkacad.com 11 Issues with Redundancy A redundant switched topology (STP disabled) may cause: • Layer 2 Loops y p • Broadcast Storms • Duplicate Unicast Frames • MAC address table instability Học viện mạng Bách Khoa - Website: www.bkacad.com 12 Layer 2 Loops • When multiple paths exist between two devices . Chapter 5 - Spanning Tree Protocol Chapter 5 Spanning Tree Protocol CCNA Exploration 4.0 Objectives • Explain the role of redundancy. when primary link down. • Via Spanning Tree Protocol Học viện mạng Bách Khoa - Website: www.bkacad.com 19 S p annin g Tree Protocol pg Học viện mạng Bách Khoa - Website: www.bkacad.com 20 . viện mạng Bách Khoa - Website: www.bkacad.com 5 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com 6 Examine a redundant design Học viện mạng Bách Khoa - Website: www.bkacad.com