How to break down a mac address? - CCENT

Raymond MasonRaymond Mason Posts: 74Member ■■□□□□□□□□
Lets say I had this MAC address: 84-3A-4B-C8-E9-00

I broke that down to decimals and I got: 132-58-75-200-233-0

How do I find the first 24 bits? How do I even take the decimals I got and put them into bits?

Out of the first 24 bits how do I find where the I/G, G/L and OUI is?

Comments

  • clarsonclarson Posts: 897Member ■■■■□□□□□□
    edited January 7
    it is better to just use the hex digits.

    each hex digit is 4 bits.  24 bits / 4 = 6 hex digits.  so the first 24 bits are the first 6 hex digits or, in your case, 84-3A-4B.  Or the first half of the MAC address as the MAC address is 48 bits in length

    the I/G is the 8th bit in the first octet.  the first octet is 0x84 or 1000 0100.  the 8th bit is zero.
    the g/l is the 7th bit of the first octet.  and from above it is also zero.

    5th   0
    6th   1
    7th   0  <- g/l bit
    8th   0  <- i/g bit

    and the OUI is the first 24 bits. and from above is 84-3A-4B
  • kaijukaiju Posts: 402Member ■■■■■■□□□□
    Convert the MAC from hex to binary instead of hex to decimal.

    0 = 0000
    1 = 0001
    2 = 0010
    3 = 0011
    4 = 0100
    5 = 0101
    6 = 0110
    7 = 0111
    8 = 1000
    9 = 1001
    A = 1010
    B = 1011
    C = 1100
    D = 1101
    E = 1110
    F = 1111

    So 84-3A-4B-C8-E9-00 converts to 10000100-00111010-0100101-11001000-11101001-00000000 with the portion in bold being the OUI. The remaining answers can be derived from the conversion.

    Work smarter NOT harder! Semper Gumby!
  • Raymond MasonRaymond Mason Posts: 74Member ■■□□□□□□□□
    Thank you so much you guys. I really appreciated your feedback.
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