710 Layer 2 Switching and Spanning Tree Protocol (STP) – Flashcards
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ASIC
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application-specific integrated circuits; hardware based bridging
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Address learning
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adds each hardware address to the forward/filter table
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Forward/filter decisions
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the switch looks at the destination hardware address and finds the exit interface in the MAC database
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Loop avoidance
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Spanning Tree Protocol (STP) is used to stop network loops while still permitting redundancy
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frame filtering
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The switch doesn't transmit the frame out any interface except for the destination interface preseving bandwidth
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show mac address-table
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display which MAC addresses are associated with which port interface
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broadcast storm
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the switches will flood broadcasts endlessly throughout the internetwork
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thrashing the MAC table
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constantly updating the MAC filter table with source hardware address locations that it will fail to forward a frame
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Spanning Tree Protocol (STP)
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shuts down any redundant links
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STP
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uses the spanning-tree algorithm (STA) to first create a topology database
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STP
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a layer 2 protocol that is used to maintain a loop-free switched network
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Root bridge
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all the switches in the network to elect a root bridge that becomes the focal point in the network
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Root bridge
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decides which port is blocked and which port is not
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Bridge Protocol Data Unit (BPDU)
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shared information between bridges when electing the root bridge
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Bridge ID
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The bridge with the lowest bridge ID becomes the root bridge in the network. Based on bridge priority and base MAC address.
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Nonroot bridge
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all bridges that are not the root bridge; exchange BPDUs with all bridges and update the STP topology database on all switches
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Root port
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the shortest path to the root bridge based on bandwidth and lowest Bridge ID
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Designated port
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port with the lowest Port Cost that will act as the Forwarding Port
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Port cost
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determined by the bandwidth of a link
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Nondesignated port
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have a higher cost than the designated port and become a blocking port
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Forwarding port
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the port that forwards frames
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Blocked port
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will listen to but not forward frames
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Blocking
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won't forward frames; listens to BPDUs; prevent the use of looped paths
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Listening
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prepares to forward data frames without populating the MAC address table
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Learning
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populates the MAC address table but doesn't forward data frame
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Forwarding
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sends and receives all data frames on the bridged port; designated or root port at the end of the learning state
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Disabled
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does not participate in the frame forwarding or STP
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Convergence
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all ports on bridges and switches have transitioned to either the forwarding or blocking modes; No data is forwarded until convergence is complete
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Cut-through (FastForward/Real-Time)
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the switch only waits for the destination hardware address to be received before it looks up the destination address in the MAC filter table
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FragmentFree (modified cut-through)
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the switch checks the first 64 bytes of a frame before forwarding it for fragmentation
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Store-and-Forward
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the complete data frame is received on the switch's buffer, a CRC is run, and if the CRC passes, the switch looks up the destination address in the MAC filter table
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What command will show you the forward/filter table
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show mac address-table
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If a destination MAC address is not in the forward/filter table, what will the switch do with the frame
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Flood the frame out all ports except the port it was received on
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What are the three switch functions at layer 2?
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Address learning, forward/filter decisions, loop avoidance
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If a frame is received on a switch port and the source MAC address is not in the forward/ filter table, what will the switch do?
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It will add the source MAC address in the forward/filter table and associate it with the port the frame was received on
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What is used at layer 2 to prevent switching loops?
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Spanning Tree Protocol (STP)
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Which LAN switch method receives the complete frame before beginning to forward it?
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Store-and-forward
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When is STP considered to be converged?
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When all ports are in either the blocking or forwarding mode
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Switches break up ___________________ domains
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Collision
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What is used to prevent switching loops in a network with redundant switched paths?
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Spanning Tree Protocol (STP)
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Which LAN switch method runs a CRC on every frame the switch receives?
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Store-and-forward
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Which of the following is a layer 2 protocol used to maintain a loop-free network?
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Spanning Tree Protocol (STP)
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What command will display the forward/filter table?
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show mac address-table
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What is the result of segmenting a network with a bridge (switch)? (Choose two options.)
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It increases the number of collision domains & It makes smaller collision domains.
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Which statement describes a spanning-tree network that has converged?
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All switch and bridge ports are in either the forwarding or blocking state.
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Your network design emphasizes efficient, error-free transport instead of fast transport. Which switching mode should be configured on the new switches to provide error-free transport to the network?
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Store-and-forward
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What are the three distinct functions of layer 2 switching that increase available bandwidth on the network?
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address learning, forwarding and filtering of the network, and loop avoidance
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What technology is used by Catalyst switches to resolve topology loops and ensure that data flows properly through a single network path?
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Spanning Tree Protocol (STP)
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Which of the following statements is true?
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A switch creates separate collision domains but one broadcast domain. A router provides a separate broadcast domain.
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Which of the following is true regarding layer 2 switches? (Choose two.)
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A switch is a multiport bridge & Switches learn MAC addresses by examining the source address of each frame.
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What does a switch do when a frame is received on an interface and the destination hardware address is unknown or not in the filter table?
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Floods the network with the frame looking for the device
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If a switch receives a frame and the source MAC address is not in the MAC address table, but the destination address is in the table, what will the switch do with the frame?
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Add the source address and port to the MAC address table and forward the frame out the destination port.
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Which of the following are spanning-tree switch port states?
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blocking, listening, learning, forwarding, and disabled
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What purpose in a switched LAN does STP perform?
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Prevents switching loops in a network with redundant switched paths
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Which command was used to produce the following output:
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show mac address-table
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Which of the following is a characteristic of having a network segment on a switch?
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One device per segment can send frames to the switch at a time.
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Which of the following is true in regard to bridges?
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Bridges do not isolate broadcast domains by default
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Layer 2 switching provides which of the following? (Choose four.)
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Hardware-based bridging (ASIC), Wire speed, Low latency, Low cost
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Suppose the above switch received a frame with the following MAC addresses: Source MAC: 0005.dccb.d74b Destination MAC: 000a.f467.9e8c
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It will forward the frame out port Fa0/3 only
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You are working on a network design and determine that a new testing application requires multiple hosts that must be capable of sharing data between each host and server running 10Mbps. Other departments use applications that require less than 3Mbps to the server. What should you recommend?
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Use a switch with a 100Mbps uplink to the server and 10Mbps to the hosts
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You have two switches connected together with two cross-over cables for redundancy, and STP is disabled. Which of the following will happen between the switches?
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Broadcast storms will occur on the switched network.
