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CCNA Recap: Port Security



Trunk ports and Etherchannel ports are not eligible for Port Security.
Why?

Etherchannel ports are bundled logically to look like one link with larger capacity than a single link.

Trunk ports carry all traffic.

switchport mode access
switchport port-security



Port security
  • does not care where frames come from (local device or other switches)
  • Watch incoming frames, keeps list of source MACs & counter of source macs

Sticky Secure Mac Addresses
  • Port security learns mac of each port and stores them so you don’t have to put in everyone by hand.
Because it's a switch  - Layer 2 - It's all about MAC Addresses.




show port-security [interface] #

Secure Shutdown
  • interface has been disabled because of port-security detecting a MAC address it doesn't recognize.

Protect
  • discards traffic

Restrict
  • Discards Traffic
  • Sends log / SNMP messages (161/162)

Err-Disabled Shutdown
  • discards traffic
  • Sends log / snmp messages
  • +1 violation counter per frame
  • disables interface and discards all traffic
  • default setting

Sticky

  • When someone plugs into the port, the switch remembers it. If someone else tries to, the port doesn't work.
Further Reading;

Switchport Port Security Explained

EMPLOYERS: This is me putting new skills into practice.

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