CCNA - Capitulo 7.1

CCNA - Capitulo 7.1

1. ETHERNET SWITCHING

   • ETHERNET MAC ADDRESS
     • CODED MEMORY (ROM) ADDRESS (BIA)
       • WHEN THE COMPUTER BOOTS UP
         • THE NIC COPIES ITS MAC ADDRESS FROM ROM INTO RAM
     • HEXADECIMAL
       • BASE 16
         • LETTERS A TO F AND NUMBERS 0 TO 9
     • 6 BYTES OR 48 bits
       • SOURCE / DESTINATON NIC LOCAL NETWORK SEGMENT
       • PAIR OF 12 HEXADECIMAL DIGITS
     • PAIR VALUES
       • 1 Byte OR 8 Bits
         • EXAMPLES REPRESANTATION
           • EXAMPLE 1
             • 00000000 to 11111111
             • OR
             • RANGE 00 TO FF
           • EXAMPLE
             • 0000 1010
             • OR
             • 0A
           • OBS
             • HEX NUMBERS REPRESENTED VALUE PROCEDED BY 0x TO DISTINGUISH BETWEEN DECIMAL AND HEX
     • 1 VALUES HEX
       • 4 bits
     • MAC ADDRESS MUST BE UNIQUE
       • HOW DO SUPPLIERS GUARANTEE THIS?
         • 1) REGISTRATION WITH THE IEEE DEVICE OBTAIN OUI
           • 00-60-2F
             • VENDOR ASSIGNED
             • (24 BITS OR 3 BYTES)
         • 2 ) MANUFACTURER WOULD ASSIGN ITS SERIAL NUMBER
           • 0F-01-DE
             • ORGANIZATIONALLY UNIQUE IDENTIFIER (OUI)
             • (24 BITS OR 3 BYTES)
       • ALTHOUGH THEY ARE EXCLUSIVE AND ENCODED IN THE NIC ROM, TODAY THEY CAN BE BYPASSED BY SOFTWARE.
         • LAYER 2 IS THE MOST VULNERABLE IN TERMS OF AUTHENTICATION.
   • ETHERNET MAC ADDRESS
     • FRAME PROCESSING
       • UNICAST
         • ORDER
           • DESTINATION MAC + SOURCE ADDRESS+ SOURCE IPV4 + DESTINATION IPV4
         • A LAYER 2 MAC ADDRESS WILL BE UNICAST AS THE DESTINATION WHEN: THE SOURCE HOST KNOWS THE DESTINATION, AS IT HAS ALREADY DONE ARP AND THE SWITCH MAC ADDRESS TABLE IS POPULATED.
         • SOURCE ALWAYS UNICAST
       • BROADCAST
         • IT IS NOT FORWARDED BY ROUTER
         • IS RECEIVED AND PROCESSES BY EVERY DEVICE ON THE ETHERNET LAN
         • HOW TO IDENTIFY
           • FF-FF-FF-FF-FF-FF
             • ADDRESS MAC DESTIANTION
           • ALL ONES (1S) IN THE HOST PORTION
             • IT IS FLOODED OUT ALL ETHERNET SWITCH PORTS EXCEPT THE INCOMING PORT
               • THAT LOCAL BROADCAST DOMAIN
             • OBS: DHCP FOR IPV4 IS AN EXAMPLE OF A PROTOCOL USES ETHERNET AND IPV4 BROADCAST ADDRESS
             • 255.255.255.255 172.16.30.255
       • MULTICAST
         • IS RECEIVED AND PROCESSED BY A GROUP OF DEVICES
           • SAME MULTICAST GROUP
         • HOW TO IDENTIFY
           • MAC DESTINATION - IPV6
             • FF00::/8
           • MAC DESTINATION - IPV4
             • 01-00-5E
           • MAC DESTINATION IPV4
             • 224.0.0.0 A 239.255.255.255
           • MAC DESTINATION - IPV6
             • 33-33
         • OBS:
           • USE ? STP , LLDP
         • FLOODED OUT ALL ETHERNET SWITCH EXCEPT THE INCOMIMG PORT
           • UNLESS THE SWITCH IS CONIGURED FOR MULTICAST SNOOPING
             • PORT MIRRORING
         • IT IS NOT FORWARDED BY
           • BY ROUTER
       • FRAME ACCEPTED OR NOT?
         • NIC RECEIVES ETHERNET FRAME EXAMINES DESTINATION MAC MATCH STORES RAM
           • MATCH ?
             • PASSES FRAME UP THE OSI LAYER TAKES DESEMCAPSULATION
           • DON'T MATCH ?
             • DISCARD