CCNA Explorer 3 Basic Switch Concepts and Configuration

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CSMA/CD on a multi-access half-Dublex network
  • 1. Carrier Sense
  • 2. Collision Detection
  • 3. Jam Signal
  • 4. Random Backoff
Difference between Unicast, Multicast and Broadcast
IEEE 802.3 Ethernet frame
Mac address format
Duplex settings
MAC table population step 1
MAC table population step 2
MAC table population step 3
MAC table population step 4
Collision Domain
Network Latency
Broadcast Domain
Collision Domain
Removing Server Bottlenecks
Switch Packet Forwarding Methods
  • Store-and-Forward - Gemmer pakken og tjekker for crc fejl
  • Cut-Through Switching - Switcher pakken når den har læst destinationen
    • Fast-forward - Switcher pakken med det samme den har læst destinationen
    • Fragment-free - Læser de første 64 byte og sender videre.
Symmetric vs. Asymmetric Switching
L2 and L3 Switching
L3 Switch and Router comparison

Navigating Command-Line Interfaces Modes

EXEC modes
Navigation configuration modes
Context Sensitive Help
Console Error Messages
Command history buffer
Configure the Command History Buffer
Switch Boot Sequence
Rollover cable
Watch boot sequence
Configure IP connectivity Step 1
Configure IP connectivity Step 2
Verify IP Connectivity
Configuring Duplex and Speed
Configure web interface
show mac address-table
Create static MAC entry: mac-address-table static <MAC address> vlan {1-4096, ALL} interface interface-id
Show Commands
Show Commands
Backup configuration
Restore configuration
Backup to TFTP server
Erase nvram:
Filsystem prefixer
Configure console access
Configure VTY access
EXEC mode password
Configure encypted passwords
Password recovery
Banner login
Banner motd
Telnet & SSH
Transport input telnet
Transport input SSH

Hvad med aaa new-model & username cisco password cisco

Common Security Attacks

MAC Address Flooding

MAC flooding attack step 1
MAC flooding attack step 2
MAC flooding attack step 3
MAC flooding attack step 4
MAC flooding attack step 5

SDM Templates

DHCP Spoofing

DHCP Spoofing
CDP Attack
Telnet Attack
Security Tools
Switchport Security
Switchport Security configuration
Verify port security
Secure Unused Ports

Security Violation Modes

  • Protect: When the number of secure MAC addresses reaches the limit allowed on the port, packets with unknown source addresses are dropped.
  • Restrict: When the number of secure MAC addresses reaches the limit allowed on the port, packets with unknown source addresses are dropped. A SNMP trap is sent, a syslog message is logged, and the violation counter increments.
  • Shutdown(Default[1]): In this mode, a port security violation causes the interface to immediately become error-disabled and turns off the port LED. It also sends an SNMP trap, logs a syslog message.