Ethernet Switching Flashcards
Access Mode
Forces a port to operate in access mode, typically configured on interfaces where end devices are connected. Access mode ports can be members of only one VLAN.
(STP) Blocking Port
A port that is administratively enabled on a Spanning Tree Protocol (STP) switch, which is neither a Root Port nor a Designated Port.
(STP Convergence) Blocking State
During STP convergence, ports remain in the initial Blocking state for 20 seconds with traditional STP. In this state, the port received BPDUs only.
Bridge ID (BID)
A value used to determine the Root Bridge in a Spanning Tree Topology (STP) network. The BID is made up of the Bridge Priority and the switch MAC address.
Bridge Priority
A value assigned to every switch in a Spanning Tree Protocol (STP) network, used to determine the Bridge ID (BID). By default, Cisco switches are assigned a Bridge Priority value of 32,768.
Building Access Layer
The layer in Cisco’s classic three-layer enterprise network model where end-user devices are connected. Ether
Cisco Discovery Protocol (CDP)
A Cisco-proprietary Layer 2 protocol used to discover information about adjacent CDP-enabled devices. CDP-enabled devices send and receive information from the multicast MAC address 0100-0ccc-cccc.
Content Addressable Memory (CAM) Table
A table found in Cisco Catalyst switches used for Layer 2 forwarding decisions, consisting device MAC addresses and the corresponding switch port to which they are connected. Also referred to as the MAC address table.
(STP) Designated Port
The port on each segment of a Spanning Tree Protocol (STP) topology with the lowest cost to reach the Root Bridge. Each segment has only one Designated Port.
Discarding State
The port state in Rapid Per-VLAN Spanning Tree (Rapid PVST+) where data is not being forwarded on the port, similar to the Blocking state found in traditional STP implementation.
(STP) Dynamic Auto Mode
Configures a port to passively wait for trunk formation with any neighboring device that initiates the trunk negotiation. Successful trunk formation occurs if the neighboring interface is set to trunk or desirable. This is the default switchport mode for newer Cisco switches.
Dynamic Desirable Mode
Configures a port to actively initiate trunk formation with a neighboring interface. Successful trunk formation occurs if the neighboring interface is set to trunk, desirable, or auto mode.
Dynamic Trunk Protocol (DTP)
Used to negotiate forming a trunk between two Cisco devices, enabled by default on a Cisco switch.
End-to-End VLAN
A VLAN that is dispersed across multiple switches or buildings.
EtherChannel
A port aggregation technology used to logically bundle links together physical ports, creating a single virtual port. This technology provides increased bandwidth, load-balancing, and redundancy.
Forwarding Information Base (FIB)
A table found in multilayer switches that allows the device to perform Layer 3 forwarding based on destination IP addresses.
(STP Convergence) Forwarding State
During STP convergence, this is the final port state that allows for the forwarding of data.
IEEE 802.1Q
The standard defining a system of tagging VLAN frames for identification over a trunk, often referred to as Dot1q. Dot1q tagging adds 4 bytes to every VLAN Ethernet frame, except for native VLAN frames.
Layer 2 Switch
A type of switch that makes forwarding decisions based on Layer 2 MAC address information.
Link Aggregation Control Protocol (LACP)
An open-standard protocol defined in IEEE 802.1ad, used to negotiate the automatic formation of EtherChannel.
Active, Passive modes
Link Layer Discovery Protocol (LLDP)
An open-standard Layer 2 neighbor discovery protocol defined by IEEE standard 802.1AB. LLDP-enabled devices use a variety of multicast MAC addresses for communication, all containing an OUI of 01-80-c2.
(STP Convergence) Listening State
During STP convergence, BPDUs are being listened to on all interfaces during the Listening State. This is done in order to build the spanning tree, and learn who the Root Bridge is, the local Root Port, and so on. This state lasts for 15 seconds with traditional STP.
Local VLAN
A VLAN that is localized to a single switch or building.
Long Path Cost Method
An updated method for determining Spanning Tree Protocol (STP) path cost with high speed links. The formula for determining cost is 20 Tbps / Port Speed.
