Term
| What are the advantages of Layer 2 switching? |
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Definition
Each user has dedicated bandwidth.
Quicker than routing, as it does not manipulate the packet, it either forwards, floods or drops a packet.
Break up collision domains |
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Term
| What are the three functions of a switch at layer 2? |
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Definition
Address learning
Forward/filter decisions
Loop Avoidance |
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Term
| What does address learning mean pertaining to layer 2 switches? |
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Definition
| When a frame is passed through a frame for the first time, the source MAC Address is stored in the filter table. The frame is then forwarded out all ports except the source port until it is ack'd. The Physical Address is then placed in the database for future use. |
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Term
| What does Forward/Filter mean pertaining to Layer 2 switching |
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Definition
| If a frame's destination MAC Address is in the database table it is only forwarded out that interface. If it is not known, it is forwarded out all ports. |
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Term
| What series of commands would be issues to shutdown a port if more than one host connects to it? |
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Definition
switch(config)#int fa0/1
switch(config-if)#switchport port-security maximum 1
switch(config-if)#switchport port-security violation shutdown |
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Term
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Definition
| A bridge with the lowest ID. All switches elect a root bridge. |
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Term
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Definition
| Bridge Protocol Data Unit - This is used to compare configurations with neighboring switches. This helps in the election of a root switch. |
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Term
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Definition
| This value is how all switches are tracked on the network. It is a combination of the bridge priority and the base MAC Address. The bridge with the lowest ID becomes the root bridge. |
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Term
| What is the default bridge priority? |
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Definition
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Term
| What are Nonroot Bridges? |
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Definition
| Bridges that are not elected as the root. They exchange BPDU's and STP Topology database to prevent loops and failures. |
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Term
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Definition
| Determines the best rout to a switch with multiple paths. |
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Term
| How is port cost determined? |
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Definition
| Determined by the bandwidth on the line. |
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Term
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Definition
| Is always the link directly connected to the root bridge, or the shortest path to the root bridge. |
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Term
| How is the root port determined? |
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Definition
Directly connected link.
If more than one link, port cost used
Same cost? then lower advertising ID is used |
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Term
| What is a designated port? |
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Definition
| One that has the lowest cost. This port is marked as a forwarding port. |
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Term
| What is a Nondesignated port? |
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Definition
| One with a higher cost. These ports are in blocking mode. |
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Term
| What does a blocked port do? |
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Definition
| It will only listen to frames, it will not forward them. |
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Term
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Definition
Root Bridge Elected
Every switch determines one root port
All other ports are placed in blocking state |
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Term
| By default, how often are BPDU's sent |
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Definition
| Every 2 seconds out all active ports. |
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Term
| What is the command to change the bridge priority? |
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Definition
router(config)#spanning-tree vlan 1 priority 4096
(Multiples of 4096) This switch will have 4096 for all of VLAN 1. |
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Term
| What does a priority of 0 mean on a switch |
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Definition
| The switch will always be the root. |
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Term
| What is the highest priority that can be set on a switch? |
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Definition
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Term
| What does the blocking port state do? |
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Definition
| Does not forward frames. This is default on all ports when the switch powers up. |
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Term
| What does the listening port state do? |
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Definition
| Prepares to forward data frames without populating the Mac Address table. This state is to ensure no routing loops are occurring. |
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Term
| What does the learning port state do? |
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Definition
| Listens to BPDU and learns all the paths in the network. Only populates MAC Address table and does not forward any frames. |
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Term
| What is forward delay? and what is the default value? |
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Definition
| The time it takes a port to transition from listening to learning and the default is 15 seconds. |
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Term
| What is the command to display the forward delay time? |
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Definition
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Term
| What does the forwarding port state do? |
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Definition
| Port sends and receives all data frames on the bridged port. |
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Term
| When does convergence occur on a switch |
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Definition
| When all ports are either in a forward or blocking mode. |
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Term
| What is spanning-tree portfast used for? |
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Definition
| Used when a port is connected to a server or a pc device. It will bypass the 50 second forwarding mode with STP and |
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Term
| What is the command to enable portfast? |
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Definition
| switch(config)#spanning-tree portfast |
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Term
| What is spanning-tree uplink fast? |
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Definition
| Cisco convergence that improves convergence time on a link failure. Allows a switch to find an alternate path to the root bridge before the primary link fails. |
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Term
| Where does Cisco reccomend using uplinkfast? |
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Definition
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Term
| What is spanning-tree BackboneFast? |
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Definition
| Used when a link not directly connected to a switch fails. This is to be enabled on all catalyst switches to allow for detection on indirect failures. |
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Term
| What is Rapid Spanning-Tree Protocol? |
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Definition
| Combines all the features of portfast, uplinkfast, backbone fast, into one protocol. All switches must run the same STP. |
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Term
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Definition
| Allows multiple links to appear as one link on a switch. |
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Term
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Definition
| Configured on Access layer switches that have portfast configured. This prevents the switch going into errdisabled state if it receives a BPDU |
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Term
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Definition
| This prevents BPDU's from filtering to the switch all together. |
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Term
| What is the command to enable BPDUGuard? |
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Definition
| switch(config-if)#spanning-tree bpduguard enable |
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Term
| What is the command to enable BPDUFilter? |
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Definition
| switch(config-if)#spanning-tree bpdufilter enable |
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Term
| What is the command to enable RSTP? |
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Definition
| switch(config)#spanning-tree mode rapid-pvst |
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Term
| What is the series of commands to enable and configure etherchannel? |
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Definition
switch(config-if)#int port-channel 1
switch(config-if)#switchport mode trunk nonegotiate
switch(config-if)#channel-group 1 mode desirable |
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Term
| What is the command to add a static mac address? |
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Definition
| switch(config)mac-address-table static aaaa.bbbb.cccc vlan 1 int fa0/5 |
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Term
| What is the command to set a switch as the root without having to adjust priorties? |
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Definition
| switch(config)#spanning-tree vlan 1 root primary |
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Term
| what command would you issue to disable stp on a port connect to a server |
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Definition
| switch(config)# spanning-tree portfast |
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