Frames?

coextendingcoextending Junior MemberPosts: 23Member ■■■□□□□□□□
Do we need to know how many bytes in each part of a frame? Or that the max size is 1500 and that you can fragment it?

PM shows
DLC Header 14 bytes
IP Header 20 bytes
TCP Header 20 bytes
TCP Data 1460 bytes
FCS 4 bytes
Do I need to know these numbers?

Comments

  • stryder144stryder144 Posts: 1,535Member ■■■■■■■□□□
    I am not sure that the Network+ exam goes into that depth but it might be worth noting the following:

    Preamble and frame delimiter (not part of the frame) - 8 bytes
    MAC address for destination - 6 bytes
    MAC address for source - 6 bytes
    802.1Q VLAN tag (optional) - 4 bytes
    EtherType/802.3 Length - 2 bytes
    Payload (data) - 42 to 1500 bytes
    Frame Check Sequence - 4 bytes

    Minimum frame length - 64 bytes
    Maximum frame length - 1522 bytes

    As such, I would know the minimum and maximum length and that frames have headers and trailers added to the Layer 3 packet (which is the data payload of the frame).
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  • Jon_CiscoJon_Cisco Posts: 1,677Member ■■■■■■□□□□
    Disclaimer! I have not taken the Net+ exam.

    However my experience is the fine details like that are not over emphasized on the test. It's more important to understand the structure of a frame and how the data is used by the system.
  • LunchbocksLunchbocks Senior Member Posts: 259Member ■■■■□□□□□□
    I think the biggest thing to know is that frames are layer 2 PDUs, and that routers use frames on the wire for destination devices (not to be confused with routers using packets to deliver the data to the end destination).
    Degree: Liberty University - B.S Computer Science (In Progress)
    Current Certs: MCTS | Network+
    Currently Working On: CCNA
    2019 Goals: CCNA R&S, CCNA Security, Security+, Linux+


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