CCNA 3 Labs and Study Guide - BINARYBB.INFO – @jagalbraith

318 Switching Basics and Intermediate Routing CCNA 3 Labs and Study Guide
Complete the following table.
RSTP Role Definition
Root port A single port on each switch in which the switch hears the best BPDU out of all the
received BPDUs
Designated port Of all switch ports on all switches attached to the same segment/collision domain, the
port that advertises the “best” root BPDU
Alternate port A port on a switch that receives a suboptimal root BPDU
Backup port A nondesignated port on a switch that is attached to the same segment/collision
domain as another port on the same switch
Disabled A port that is administratively disabled
RSTP calls Ethernet connections between switches links and calls Ethernet connections to end-user
devices edges. If the link is full duplex, RSTP designates it as a point-to-point link. If the link is half
duplex, RSTP designates it as a shared link. An example of a shared link is a port attached to a hub.
Determine the Root Bridge and Port Roles Exercise
Instructor Note: This exercise will prove challenging for many students. However, you can enhance their understanding
of STP concepts and operation by reviewing the online curriculum for CCNP 3, Module 3: Objective 3.1,
“Defining the Spanning Tree Protocol—STP.”
The root bridge is chosen based on the lowest BID. After the root bridge is selected, a non-root bridge
looks at the following components in sequence to determine which ports will process user data and which
ports will discard user data:
1. On each non-root bridge, the port with the lowest path cost to root is the root port.
2. If two or more bridges are members of the same segment and have the same cost to reach the root
bridge, the bridge with the lowest BID is the designated port for that segment.
3. If a bridge has two or more equal cost paths to root, the port with the lowest ID is designated port.
The other port(s) is blocking.
In the topologies shown in Figures 7-2, 7-3, and 7-4, circle the root bridge. On non-root bridges, label root
ports with an R, designated ports with a D, and ports that are in the blocking state with a B. Use the
revised IEEE costs to make your determinations. In the space provided after each topology, draw the logical
loop-free spanning-tree topology with the root bridge at the top.