Switch Glossary¶
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802.1Q VLAN
The IEEE standard for VLAN tagging in an Ethernet network. It adds a 4-byte header to Ethernet frames to identify the VLAN membership.
802.1p
A Quality of Service (QoS) mechanism that prioritizes traffic based on the 3-bit priority field in the 802.1Q VLAN tag.
802.1X
An IEEE standard for port-based network access control that authenticates devices before granting access to the switched network.
Aging Time
The timeout period after which a switch removes a dynamic MAC address entry from its address table if no traffic is received from that source.
Access Port
A switch port configured to carry traffic for a single VLAN, typically used to connect end devices such as PCs or IP phones.
ACL
(Access Control List) A set of rules applied on a switch to permit or deny traffic based on criteria such as source/destination IP address, MAC address, or protocol type.
ARP
(Address Resolution Protocol) A protocol used to map an IP address to a corresponding MAC address within a local broadcast domain.
Auto-Negotiation
A mechanism that allows Ethernet devices to automatically determine and configure the optimal speed and duplex mode for a link.
Backup Restore
The utility used to save the switch's current configuration to a file (Backup) and write a previously saved configuration back to the device (Restore).
Backplane Bandwidth
The maximum aggregate data throughput that the internal switching fabric of a switch can support.
Bandwidth Control
A traffic management feature that limits the maximum bandwidth available to a port or traffic class.
BPDU
(Bridge Protocol Data Unit) Control packets exchanged between switches to build and maintain a Spanning Tree topology.
Broadcast
A communication method in which a frame is delivered to all devices within the same Layer 2 broadcast domain.
Cable Diagnostics
A feature that tests the physical condition of the Ethernet cables connected to the ports, detecting issues like shorts or cable length.
Chassis ID
A unique identifier for the switch chassis, often the device's base MAC address, used for identification in discovery protocols like LLDP.
Circuit ID
A sub-option in DHCP Snooping (Option 82) that identifies the specific physical port or VLAN from which a DHCP request was sent.
Cost Metric
A value assigned to a link in Spanning Tree Protocol (STP). The protocol uses this to calculate the shortest (lowest cost) path to the Root Bridge.
DHCP Snooping
A Layer 2 security feature that validates DHCP messages and filters out unauthorized (rogue) DHCP server responses.
DSCP
(Differentiated Services Code Point) A Layer 3 QoS mechanism that uses the 6-bit DiffServ field in the IP header to classify and prioritize traffic.
DoS Protection
Mechanisms designed to detect and mitigate denial-of-service attacks that could disrupt switch operation.
Duplex
The transmission mode of a network link, defined as half-duplex or full-duplex communication.
Dynamic Routing
Routing in which a switch automatically learns network paths using routing protocols such as OSPF or RIP.
EEE Config
(Energy-Efficient Ethernet) Configuration for the IEEE 802.3az standard, designed to reduce power consumption during periods of low data activity.
Egress
Refers to the traffic that is leaving or exiting a switch port.
Ethernet Port
A physical network interface, typically using an RJ45 connector, for Ethernet-based communication.
Extended Power
A PoE feature that allows power delivery over distances exceeding the standard 100-meter limit, often at a reduced data rate.
Fast-leave
An IGMP Snooping feature that allows the switch to immediately stop forwarding multicast traffic to a port when an IGMP Leave message is detected.
Firmware Upgrade
The process of replacing the switch's current operating software with a newer version to fix bugs or add new features.
Flow Control
A mechanism (IEEE 802.3x) that manages the data transmission rate between two nodes to prevent the receiver's buffer from overflowing.
Forward Delay
The time a port spends in the Listening and Learning states before it starts forwarding data in Spanning Tree Protocol.
Fullplex
A technical shorthand for Full Duplex, where a port can transmit and receive data simultaneously.
Failover
The automatic switching of traffic to a backup link or port when the primary link fails.
Flooding
The process of forwarding frames out of all ports except the incoming port when the destination MAC address is unknown.
Forwarding
The action of transmitting frames from an ingress port to the appropriate egress port based on switching logic.
Forwarding Rate
The number of packets per second (Mpps) that a switch can process and forward.
Frame
The fundamental unit of data transmission at the Data Link Layer (Layer 2).
IGMP Querier
A device (usually a router or L3 switch) that sends IGMP Query messages to discover which hosts belong to which multicast groups.
IGMP Snooping
A mechanism that allows a Layer 2 switch to examine IGMP packets to maintain a multicast forwarding table, preventing multicast floods.
Ingress
Refers to the traffic that is entering or coming into a switch port.
Ingress Filter
A security feature that drops incoming frames if the VLAN ID in the frame does not match the port's VLAN membership.
ICMP
(Internet Control Message Protocol) A protocol used for network diagnostics and error reporting, commonly utilized by ping and traceroute.
IEEE 802.1Q
The IEEE standard defining VLAN tagging in Ethernet frames.
Inter-VLAN Routing
The capability of a Layer 3 switch to route traffic between different VLANs.
Jumbo Frame
Ethernet frames with a payload greater than the standard 1,500 bytes, typically up to 9,000 bytes, used to increase data transfer efficiency.
LAG
(Link Aggregation Group) A logical interface formed by bundling multiple physical ports to increase bandwidth and provide redundancy.
Latency
The time delay experienced by a packet as it is processed and forwarded by the switch.
Layer 2 Switch
A switch that forwards traffic based on MAC addresses and operates primarily at the Data Link Layer.
Layer 3 Switch
A switch capable of performing both Layer 2 switching and Layer 3 routing functions.
LLDP
(Link Layer Discovery Protocol) An IEEE 802.1AB protocol that allows network devices to advertise identity and capabilities to directly connected neighbors.
LLDP Config
(Link Layer Discovery Protocol Configuration) Settings for the vendor-neutral protocol used by devices to advertise their identity and capabilities.
LLDP Neighbor
Information about directly connected devices that are also running the Link Layer Discovery Protocol.
Loop
A network condition where frames circulate endlessly, potentially causing broadcast storms and network instability.
Loop Guard
A protection mechanism that prevents alternate ports from incorrectly transitioning to the forwarding state in STP topologies.
Loop Prevention
A general term for techniques (like STP) used to detect and block physical loops in a network that could cause broadcast storms.
Load Balancing
The distribution of traffic across multiple physical links within a link aggregation group.
MAC
(Media Access Control) The unique 48-bit hardware address assigned to a network interface controller.
MAC Address
A unique hardware identifier assigned to a network interface for Layer 2 communication.
MAC Address Table
A table maintained by a switch that maps MAC addresses to the ports on which they are learned.
MAC Binding
A security feature that statically associates a MAC address with a specific switch port.
MAC Manage
The administrative interface for viewing the MAC address table, configuring static MAC entries, and setting security bindings.
Max Age
The maximum amount of time an STP bridge waits without receiving a BPDU before concluding that the topology has changed.
Managed Switch
A switch that supports configuration, monitoring, and management through interfaces such as Web UI, CLI, or SNMP.
Med Capabilities
(LLDP-MED) Extensions to LLDP for Media Endpoint Discovery, used to automatically configure devices like VoIP phones.
Mirrored port
The source port in a port mirroring setup; the port whose traffic is being monitored.
Mirroring port
The destination port in a port mirroring setup; the port where the traffic analyst or packet sniffer is connected.
MTU
(Maximum Transmission Unit) The largest size of a packet or frame that can be sent over a specific network interface.
MTU VLAN
A VLAN configuration where multiple "leaf" ports are isolated from each other but share access to a single "uplink" port.
Multicast
A transmission method where a single sender sends data to a specific group of interested receivers.
MSTP
(Multiple Spanning Tree Protocol) An IEEE 802.1s protocol that maps multiple VLANs to a reduced number of spanning tree instances.
Network Policy
Settings within LLDP-MED used to assign VLANs, priorities, and DSCP values to specific types of traffic, such as Voice.
OUI
(Organizationally Unique Identifier) The first three bytes of a MAC address that identify the manufacturer of the device.
Pair
Refers to the two-wire twisted pairs inside an Ethernet cable (e.g., Cat6 has 4 pairs).
Packet
A formatted unit of data transmitted at the Network Layer (Layer 3).
Packet Buffer
Memory within a switch used to temporarily store packets during congestion or processing delays.
Ping Tool
A diagnostic utility that sends ICMP Echo Request packets to a target IP to check connectivity and measure latency.
PD
(Powered Device) A network device, such as an access point or IP camera, that receives power via PoE.
PoE
(Power over Ethernet) A technology that delivers electrical power and data over standard Ethernet cabling.
PoE Budget
The total amount of power available on a PoE-capable switch for supplying connected devices.
PoE Priority
A mechanism that defines which ports receive power first when PoE power is limited.
Port Isolation
A feature that restricts communication between specific ports while allowing access to uplink ports.
Port Management
The general administrative category for configuring physical port properties and statuses.
Port Mirror
The feature that copies traffic from one port (source) to another port (destination) for network analysis.
Port Settings
Individual port configurations including speed, duplex, flow control, and port description.
Port Trunk
Also known as Link Aggregation; the process of combining multiple physical ports into one logical high-bandwidth link.
Port-based
A classification method (often for QoS or VLANs) that applies rules based on the physical port the traffic enters.
Port-based VLAN
A VLAN configuration where the VLAN membership is defined by the physical port on the switch.
Priority
A value used to determine the importance of a packet (QoS) or the role of a device in a network protocol (STP Bridge Priority).
Protocol Management
The configuration section for global network protocols like SNMP, LLDP, and IGMP.
PSE
(Power Sourcing Equipment) A device, typically a switch, that supplies power to PoE-enabled devices.
PVID
(Port VLAN ID) The default VLAN ID assigned to any untagged frames entering a switch port.
QoS
(Quality of Service) A set of techniques used to prioritize critical traffic and manage network congestion.
Rate Limiting
A method of restricting the maximum rate of traffic transmitted or received on a port.
Report Suppression
An IGMP Snooping feature that limits the number of IGMP Join reports forwarded to the router to reduce control plane traffic.
Round Trip Time
(RTT) The time it takes for a signal to be sent plus the time it takes for an acknowledgment to be received.
RSTP
(Rapid Spanning Tree Protocol) An evolution of STP (IEEE 802.1w) that provides faster convergence when a network topology changes.
Rx bytes
The total number of data bytes received on a specific interface.
Rx pkts
The total number of packets received on a specific interface.
Session
A temporary logical connection or interaction between two communicating network devices or a user and the management interface.
SNMP
(Simple Network Management Protocol) A protocol used for collecting information from and configuring network devices such as switches and routers.
Snooping
The process of an intermediate device (like a switch) inspecting traffic (like DHCP/IGMP) to improve efficiency or security.
SP
(Strict Priority) A QoS scheduling method that always empties the highest-priority queue before servicing any lower-priority queues.
Spanning Tree
(STP) A Layer 2 protocol (IEEE 802.1D) that prevents logical loops in a network with redundant physical paths.
Speed Limit
Also known as Rate Limiting; the process of limiting the maximum transmission rate on a port (Ingress or Egress).
Static Routing
Routing paths that are manually configured and do not change dynamically.
Store-and-Forward Switching
A switching method that receives and verifies an entire frame before forwarding it.
Storm Control
A security feature that limits the level of Broadcast, Multicast, or Unknown Unicast traffic to prevent network degradation.
STP
(Spanning Tree Protocol) An IEEE 802.1D protocol that prevents Layer 2 loops by creating a loop-free topology.
Switching Capacity
The total amount of traffic a switch can handle across all ports simultaneously.
System Reboot
A command to restart the switch software and hardware without changing the configuration.
System Reset
A command to restore the switch to its original factory default settings.
Tagged port
A port configured to carry traffic for multiple VLANs, where each frame includes an 802.1Q tag identifying its VLAN.
Threshold
A configured value that, when crossed, triggers an alert, log entry, or specific action by the switch management software.
Traffic Monitor
A real-time display or log showing the data rate (Kbps/Mbps) and packet flow across the switch's interfaces.
Transmit Hold Count
An STP parameter that limits the number of BPDUs the switch can send in a short interval to prevent CPU exhaustion.
Trap Server
The IP address of the management station (NMS) where the switch sends unsolicited SNMP Trap messages.
Trap type
Specific event categories (e.g., link up/down, cold start) that trigger an SNMP Trap notification.
Trunk Group
A logical collection of physical ports configured to work together as a single Link Aggregation Group (LAG).
Trunk Port
A switch port configured to carry traffic for multiple VLANs using VLAN tagging.
TTL
(Time to Live) A field in an IP packet that limits the packet's lifetime. Each router it passes through decreases the TTL by one.
Tx bytes
Statistics showing the total volume of data (Bytes) transmitted (sent) by a port.
Tx Delay
Timing parameters for protocol packets (like LLDP); defines the delay between sending individual protocol frames.
Tx Hold
A multiplier used to calculate the Time-to-Live (TTL) for information transmitted in discovery protocols.
Tx Interval
The frequency (in seconds) at which a device sends out periodic protocol updates (like LLDP or STP).
Tx pkts
Statistics showing the total number of packets transmitted (sent) by a port.
Unicast
A transmission sent from a single source to a single specific destination on the network.
Untagged port
A port where outgoing frames do not contain a VLAN tag; typically used for connecting end-user devices like PCs.
Uplink
A port, often with higher speed, used to connect a local switch to a core switch, router, or the wider network.
Unmanaged Switch
A plug-and-play switch without configuration or management capabilities.
VID
(VLAN ID) The numerical ID (1–4094) used to identify a specific Virtual LAN within an Ethernet frame tag.
VLAN
(Virtual LAN) A logical grouping of devices within a switch that creates separate broadcast domains.
VLAN ID
A numerical identifier assigned to a VLAN, ranging from 1 to 4094.
Voice VLAN
A specialized VLAN that prioritizes voice traffic (VoIP) over data traffic to ensure call quality even during network congestion.
Web UI
A browser-based graphical interface for switch configuration and monitoring.
WFQ
(Weighted Fair Queuing) A QoS scheduling algorithm that gives different traffic flows a "fair" share of bandwidth based on their assigned weights.
WRR
(Weighted Round Robin) A QoS scheduling algorithm that cycles through queues and sends a certain amount of data from each, proportional to its weight.