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65 Cards in this Set
- Front
- Back
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Why was the Spanning Tree Protocol (STF) developed? |
To prevent loops in L2 networks |
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What are Application-Specific Integrated Circuits (ASICs)? |
Switch-based hardware circuits used to maintain hardware address tables |
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What disadvantage does redundancy in L2 networks create? |
The possibility of loops |
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What are the 2 key points to consider when designing a switched network? |
Collision domains should be broken ups much as possible; and users.should spend 80% of time on local segment |
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Do bridges provide hardware- or software-based L2 management? |
Software-based management |
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Do switches provide hardware- or software-based L2 management? |
Hardware-based |
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Do bridges support more than 1 spanning tree instance? |
No |
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Do switches support more than 1 spanning tree instance? |
Yes |
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What are the 3 functions of an L2 switch? |
Learning MAC addresses, filtering and forwarding frames, and preventing loops |
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Where do switches store MAC addresses? |
In a Content-Addressable Memory (CAM) table |
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What does a switch do when it receives a frame for an unknown recipient? |
Forwards it to every port except the originator |
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What does a switch do when it receives a frame from a port not listed in its CAM table? |
Records the sander's MAC and processes the frame |
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What is the MAC address aging time? |
The length of time a switch will store a sender's MAC address |
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What is the default MAC address aging time? |
300 sec. (5 min.) |
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What command will show a switch's CAM table? |
Show mac address-table |
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What is frame filtering? |
Switch behavior where a frame is forwarded only to a specific port if known |
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What are the 3 switching modes? |
Cut-through, store-and-forward, and fragment-free (modified cut-through) |
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What switching mode is fastest? Why? |
Cut-through: frame only read up to destination address |
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What switching mode has the highest latency? |
Store-and-forward |
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How does store-and-forward switching work? |
Entire frame read into buffer, CRC run, and runts, giants, and frames that fail CRC are discarded |
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How does fragment-free switching work? |
The first 64 bytes are checked for errors, then packet is forwarded |
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What command turns on switch port security? |
Switchport port-security |
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What 3 things can be configured in switch port security? |
Who can connect, how many can connect, and violation action |
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What command will limit switch port access to a given MAC? |
Switchport port-security mac-address |
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What command will restrict access to the first device to connect to a port? |
Switchport port-security mac-address sticky |
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What command will set a maximum number of simultaneous connections to a switch port? |
Switchport port-security maximum <#> |
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What are the 3 possible violation actions for port security? |
Shutdown, protect, and restrict |
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What happens when a violation occurs while a switch port is has port security set to shutdown? |
Switch port is disabled until an administrator manually shuts down and re-enables the port |
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What happens when a violation occurs and the switch port's security is set to protect? |
Frames from the offending machine are discarded |
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What happens when a violation occurs and a switch port's security is set to restrict? |
Frames from the offending machine are discarded and an SNMP and/or syslog message are sent to the administrator |
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How is a port's violation action configured? |
Switchport port-security { shutdown | protect | restrict } |
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What command will show the port security settings on a given interface? |
Show port-security interface |
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What command will show port security settings on all interfaces? |
Show port-security |
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What is the unique ID for a switch called? |
The bridge ID |
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What does a bridge ID consist of? |
The bridge priority + the switch's MAC address |
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What is the default priority for a bridge or switch? |
32,768 |
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What are the possible values for a bridge priority? |
0-61,440 in increments of 4096 |
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How is a root bridge selected? |
Elected by all bridges in a network |
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What bridge is selected as the root bridge? |
The bridge with the lowest bridge ID |
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What is a Bridge Protocol Data Unit? |
The informations shared among bridges and switches to allow them to select a root bridge and configure the network |
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What is the information shared among bridges and switches to allow them to elect a root bridge and configure the network called? |
Bridge Protocol Data Units (BPDU's) |
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How often do Cisco switches send BPDU's by default? |
Every 2 sec. |
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What is the Root Port? |
The port on a switch with the fastest path to the root bridge |
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What is a port cost? |
The cost of a link as determined by bandwidth |
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What is port cost used for? |
Determining which redundant links will be used and which will be blocked |
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What cost does STP assign to a 4 Mbps link? |
250 |
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What cost does STP assign to a 10 Mbps link? |
100 |
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What cost does STP assign to a 16 Mbps link? |
62 |
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What cost does STP assign to a 100 Mbps link? |
19 |
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What cost does STP assign to a 1 Gbps link? |
4 |
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What cost does STP assign to a 10 Gbps link? |
2 |
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What is a designated port? |
The bridge with the lowest-cost path to the root bridge |
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What are the 5 port states in STP? |
blocked, listening, learning, forwarding, disabled |
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What happens when a port is in blocked state? |
the port will not transmit or receive data, but will receive BDPUs |
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What happens when a port is in listening mode? |
the port listens for frames but discards them, and does not build a CAM table |
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What does a port do when it is in learning mode? |
the port builds a CAM table and transmits its own BPDUs |
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What happens when a port is in forwarding mode? |
the port will send and receive frames |
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What 3 things need to occur before STP is considered to be converged? |
the root bridge is elected, the root ports are elected, and the designated ports are elected |
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What ports on the root bridge are considered to be designated? |
all of them |
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How many root ports are chosen on non-root bridges? |
one |
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What state will a root port be set to? |
forwarding |
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What do designated ports do? |
forward traffic and BDPUs to the segment |
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What mode should you be in to configure errdisable autorecovery? |
Global config mode |
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What 2 commands will configure errdisable autorecovery? |
Errdisable recovery cause <cause> Errdisable recovery interval <seconds> |
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What command will show which causes will permit autorecovery from an errdisable state and which ports are scheduled to autorecover? |
Show errdisable recovery |
