DATA COM 2 - MIDTERMS

Converged Networks

Modern enterprise networks carry multiple types of traffic (voice, video, and data) over a shared network infrastructure[cite: 300].

Access Layer

Connects end devices like PCs, phones, and printers to the network[cite: 302].

Distribution Layer

Aggregates access networks and provides Layer 3 boundaries and policies[cite: 302].

Core Layer

The high-speed backbone connecting major parts of the network[cite: 302].

Collapsed-Core

Smaller networks often combine the Distribution and Core layers into a two-tier design for simplicity while maintaining structured connectivity[cite: 302, 303].

Fixed Configuration Switches

Switches with predetermined ports[cite: 304].

Modular Configuration Switches

Switches that allow adding line cards[cite: 304].

Stackable Configuration Switches

Multiple switches operating as a single logical group[cite: 304].

MAC Address Learning

When a frame enters a switch port, the switch reads the source MAC address and associates it with the incoming interface, storing this in its MAC address table[cite: 306, 307].

Known Unicast Forwarding

If the destination MAC is in the table, the switch forwards the frame exclusively out the associated port[cite: 309, 310].

Unknown Unicast & Broadcast Forwarding

If the destination MAC is not in the table, or if it is a broadcast frame, the switch floods the frame out all ports in the broadcast domain except the ingress port[cite: 309, 310].

Store-and-Forward Switching

Receives the entire frame and checks the Frame Check Sequence (FCS) for errors before forwarding[cite: 311].

Cut-Through Switching

Begins forwarding as soon as the destination MAC address is read[cite: 312].

Fragment-Free Switching

Waits for the first 64 bytes to pass before forwarding to eliminate fragment errors[cite: 312].

Collision Domains

Network segments where devices might contend for the same medium[cite: 314].

Broadcast Domains

The set of devices that receive a Layer 2 broadcast[cite: 315].

Switch Virtual Interface (SVI)

An interface assigned an IP address, subnet mask, and default gateway for remote switch management (commonly referred to as the management VLAN)[cite: 323].

Auto-MDIX

A feature that allows the switch to automatically detect and adjust to the required cable type (straight-through or crossover)[cite: 327].

Runts/Giants

Frames smaller than 64 bytes or larger than 1,518 bytes[cite: 333].

CRC Errors

Checksum failures indicating corrupted frames[cite: 333].

Late Collisions

Collisions occurring after 512 bits of the frame have been transmitted[cite: 333].

Secure Shell (SSH)

A secure protocol that replaces unsecure Telnet by encrypting management traffic[cite: 336].

Port Security

A feature that limits the number of valid MAC addresses allowed on a port[cite: 341].

Protect Violation Mode

A port security mode that drops unauthorized traffic quietly[cite: 342].

Restrict Violation Mode

A port security mode that drops traffic, generates a syslog message, and increments the violation counter[cite: 342].

Shutdown Violation Mode

The default port security mode that drops traffic, logs a message, increments the counter, and places the port into an err-disabled state[cite: 342].

Full-duplex

A port configuration that completely eliminates traditional Ethernet collisions within a collision domain[cite: 314, 316].

Management VLAN

The VLAN associated with the Switch Virtual Interface (SVI) for remote management, which should ideally be a VLAN other than VLAN 1 for security[cite: 323].

Sticky MAC addresses

Secure MAC addresses that are dynamically learned by the switch and saved to the running configuration[cite: 341].

Err-disabled state

An error state a port is placed into when a security violation occurs under the Shutdown mode; recovering from it requires manually issuing a 'shutdown' followed by a 'no shutdown' command[cite: 342, 349].

VLAN

A logical Layer 2 network segment where each forms a separate broadcast domain[cite: 358].

Data VLAN

A VLAN that carries user or application traffic[cite: 360].

Voice VLAN

A VLAN that carries IP phone traffic[cite: 360].

Management VLAN

A VLAN that carries switch management traffic[cite: 360].

Native VLAN

A VLAN that carries untagged traffic on an 802.1Q trunk[cite: 360].

IEEE 802.1Q

A standard that defines the VLAN tagging mechanism for Ethernet frames crossing a trunk[cite: 361, 363].

Trunk Link

A link that carries traffic for multiple VLANs over one connection[cite: 361].

Broadcast Domain

A logical division where a broadcast is forwarded only within the originating VLAN[cite: 362].

VLAN 1

The default VLAN of Cisco switches that cannot be deleted or edited[cite: 365].

Normal VLAN Range

VLAN IDs 2 through 1001, which can be manually created, edited, and deleted[cite: 365].

Extended VLAN Range

VLAN IDs 1006 through 4094[cite: 365].

Access Port

A switch port assigned to a specific VLAN for connecting end devices[cite: 368].

Inter-VLAN Routing

The routing of traffic between different VLANs using a Layer 3 device[cite: 382].

Router-on-a-Stick

An inter-VLAN routing method that uses one physical router interface for multiple VLANs via subinterfaces[cite: 383].

Subinterface

A logical interface created on a physical router interface, assigned an IP address and encapsulation tag to serve as a default gateway for a VLAN[cite: 383, 386].

VLAN 0 & VLAN 4095

Reserved VLANs which cannot be seen or used[cite: 365].

VLAN 1002-1005

Cisco default VLANs for FDDI and Token Ring that cannot be deleted[cite: 365].

802.1Q VLAN Tagging

A mechanism where Ethernet frames crossing a trunk are identified with VLAN information, which is removed before the frame is sent through an access port[cite: 363].

VLAN ID

An identifier within the 802.1Q tag that specifies the VLAN associated with the frame[cite: 363].

vlan.dat

A file located in flash memory where VLAN configurations are saved; it can be entirely removed using the 'delete flash:vlan.dat' command[cite: 370].

MAC address table

A table where a switch records learned source MAC addresses and their associated ports[cite: 395, 398].

Known unicast

A forwarding decision where the destination MAC address is in the MAC address table, allowing the switch to forward the frame exclusively through the appropriate port[cite: 396].

Unknown unicast

A forwarding decision where the destination MAC address is not yet known, causing the switch to flood the frame within the switching domain[cite: 396].

Broadcast

A frame addressed to the MAC address FF:FF:FF:FF:FF:FF, which the switch floods out all ports[cite: 396].

switchport port-security

A configuration command that enables port security on the interface[cite: 396].

switchport port-security maximum 1

A configuration command that permits only one secure MAC address on an interface[cite: 396].

switchport port-security mac-address sticky

A configuration command that dynamically learns and retains the MAC address as a secure address[cite: 397].

switchport port-security violation shutdown

A configuration command that places the port into a disabled state when a security violation occurs[cite: 397].

show running-config

A command used to view the current active configuration[cite: 398].

show startup-config

A command used to view the saved configuration[cite: 398].

show interfaces status

A command used to view switch port status, including speed, duplex, and connected devices[cite: 395, 398].

show mac address-table

A command used to view the MAC addresses the switch has learned[cite: 395, 398].

show port-security

A command used to view a summary of port-security settings[cite: 398].

show port-security interface

A command used to view detailed port-security information for a specific interface[cite: 398].

show port-security address

A command used to view the secure MAC addresses learned by the switch[cite: 398].

copy running-config startup-config

A command used to save the current configuration to startup configuration[cite: 394, 398].

MAC Address Learning

The process where a switch learns the source MAC address of an incoming Ethernet frame and associates it with the port where the frame was received[cite: 393, 395, 398].

Security-violation/disabled state

The state a secured interface enters when the switch detects an unauthorized or different MAC address on it[cite: 397].

enable

A command used to enter privileged EXEC mode on the switch[cite: 394].

configure terminal

A command used to enter global configuration mode[cite: 394].

hostname

A command used to configure the device's hostname[cite: 394].

enable secret

A command used to configure the privileged EXEC password[cite: 394].

line console 0

A command used to enter configuration mode for console access[cite: 394].

line vty 0 4

A command used to enter configuration mode for VTY (remote) access[cite: 394].

interface

A command used to enter interface configuration mode for a specific port (e.g., interface fa0/1)[cite: 394, 396, 397].

description

A command used to add a description to a switch port[cite: 394, 395].

no shutdown

A command used to enable or turn on a port[cite: 394, 395].

switchport mode access

A command used to configure a switch port as an access port[cite: 396].

shutdown

A command used to manually disable an interface, often used alongside 'no shutdown' to reset a port recovering from a security violation[cite: 397].

clear port-security sticky interface

A command used to clear the dynamically learned sticky MAC entry before relearning an authorized device[cite: 398].