7 - Switches Flashcards
What protocol is used to prevent loops on a switch?
STP or spanning tree protocol
What are the names of the led lights on a switch?
Syst or system rps or redundant power system stat or port status duplx or duplex speed
What are the switching modes?
store and forward switching
cut through switching
adaptive cut through switching
fragment free switching
What switching mode receives the entire frame before forwarding the frame? It also verify that no CRC errors are present.
Store and forward switching mode
What switching mode begins forwarding a frame after the first six bytes forwarding the frame before its fully received?
cut through switching mode
What switching mode provides a balance between store and forward switching and cut through switching?
adaptive cut through switching mode
What switching mode has to receive 64 bytes of the frame before deciding whether to forward the frame?
fragment free switching mode
What standard allows compliant devices to automatically communicate port speed and duplex over a 10Mb or 100Mb connection?
IEEE 802.3u
What standard allows compliant devices to automatically communicate port speed and duplex over a 1000Mb connection?
IEEE 802.3z
What is displayed in the show interfaces command?
status of interfaces ip addresses interface speeds number of packets sent and received error counts
What is a cause of excessive noise?
usually a physical media problem, bad cable
How do you detect excessive noise errors?
show interfaces:
high number of CRC errors
low number of collisions
What is a cause of too many collisions?
too many nodes on a segment
bad nic
duplex mismatch
How do you detect collision errors?
show interfaces:
high number of collisions
What is a symptom of late collision errors?
duplex mismatch
network segment is too long
How do you detect late collision errors?
show interfaces:
high number of late collisions
What is a symptom of duplex mismatch errors?
intermittent connectivity
performance problems
How do you detect duplex mismatch errors?
show interfaces:
high number of collisions
high number of late collisions
What is a symptom of speed mismatch errors?
prevents the interface from sending traffic
How do you detect speed mismatch errors?
show interfaces status:
check the speed setting
also the interface is usually down
What is a symptom of a broadcast storm?
network slowness
cpu utilization is high on switch and computers
loop in the network
How do you view the cpu usage on a switch?
show processes command
How do you detect broadcast storm errors?
show interfaces:
high collision count
show processes:
high cpu usage 80 - 100%
What methods can be used to secure a switch?
disable unused ports
configure port security
What is the default mac address count when port security is enabled?
one mac address
Where are the mac addresses stored when the sticky keyword is used in switchport port-security mac-address sticky?
in the running config, they will be lost unless the config is writ memed
What are the three keywords available for switchport port-security violation command?
restrict protect shutdown (default)
What does the restrict keyword do in switchport port-security violation restrict?
configures the switch to drop traffic from any mac that is not allowed, create a log entry documenting the violation
What does the protect keyword do in switchport port-security violation protect?
configures the switch to drop traffic from any mac that is not allowed, does not create a log entry documenting the violation
What is the command to configure automatic error-disabled recovery?
errdisable recovery interval 100
What command can be used to view port-security configuration?
show port-security
What standard is STP based off of?
IEEE 802.1D
What layer of the OSI model does spanning tree operate on?
layer 2
What are the states of STP?
forwarding
blocking
What is PortFast in STP?
feature that provides immediate access to the network for edge ports
What are the global configuration commands for portfast?
spanning-tree portfast
spanning-tree portfast interface fa0/1
What is BPDU Guard?
used to disable ports that erroneously receive BPDUs.
Where should BPDU guard be used?
on edge ports that have portfast enabled
What is loop guard?
feature that prevents nondesignated ports from inadvertently forming bridging loops if the steady flow of BPDUs is interrupted
What is the global configuration command for loop guard?
spanning-tree loopgaurd default
What is the interface command for loop guard?
spanning-tree guard loop
What is root guard?
is used to prevent newly introduced switches from being elected as the new root switch
What is the global configuration command for root guard?
None, it is only configured on the interface
What is the interface command for root guard?
spanning-tree guard root
What happens when root guard is enabled on port that has loop guard enabled?
loop guard will be disabled
