3 ms·

Ethernet deals with frames, not packets. Packets are an IP concept :)

by sgjohnson 2y ago

anilakar 2y ago
Packets are a TCP concept. IP sends datagrams :)
- samarthr1 2y ago
  I thought UDP sent datagrams?
  - deleted 2y ago
    [deleted]
  - tsimionescu 2y ago
    Both IP and UDP call their packets "datagrams".
- brewmarche 2y ago
  The TCP unit is called segment
  - cat-snatcher 2y ago
    No it's called a slice.
mhandley 2y ago
RFC 791 which defines IP talks about both packets and datagrams. IP sends datagrams. Each IP datagram is fragmented into one or more packets depending on the underlying L2 network. But RFC 791 dates from when the underlying L2 network was most likely ARPAnet, which had 128 byte packets. Today the distinction is (or should be) moot - if you're relying on IP fragmentation to send your large IP datagram over multiple L2 packets, you're doing something wrong. IPv6 doesn't even support in-network fragmentation. In practice, the distinction has largely disappeared over time. Everyone I know talks about packets and very rarely bothers to distinguish between frames, datagrams and packets, because in practice one Ethernet frame generally carries one IP datagram, and everyone calls it a packet.
xnorswap 2y ago
Only on HN could someone implement networking from scratch, only to be dismissed by someone in the comments implying they've no idea what they're doing.
- Angostura 2y ago
  I think the comment was implying that they got word wrong, not that they had "no idea what they were doing". Bit overly dramatic
  - xnorswap 2y ago
    The comment stated they got the word wrong, the implication is that it was out of ignorance. Yet the article uses frame throughout where technically correct, and what was important to the author wasn't that any frame was transmitted, but that they got their packet to show up correctly.
    - bigstrat2003 2y ago
      I certainly disagree that the implication you read into it was there. I read the statement as a friendly bit of banter, not an implied accusation of ignorance.
      - erinaceousjones 2y ago
        Only on HN could someone implement networking from scratch, only to be dismissed by friendly banter in the comments implying they've no idea what they're doing, only for that to be misinterpreted as actual criticism, only for an analysis to be done on this comment thread :-) only for dang to appear and ask us to stop being so meta. Also, in TFA the font is 3 pixels too far to the left and it made it literally unreadable for me
- sitzkrieg 2y ago
  talking to a chip over spi is not what id call scratch, lol
crest 2y ago
Smartass. Did you understand the title anyways?
donaldihunter 2y ago
For Ethernet, packets are a physical layer concept. They encapsulate frames which are a data link layer concept. https://en.wikipedia.org/wiki/Ethernet_frame https://en.wikipedia.org/wiki/Ethernet_frame

Ethernet deals with frames, not packets. Packets are an IP concept :)

anilakar 2y ago

Packets are a TCP concept. IP sends datagrams :)

samarthr1 2y ago
I thought UDP sent datagrams?
- deleted 2y ago
  [deleted]
- tsimionescu 2y ago
  Both IP and UDP call their packets "datagrams".
brewmarche 2y ago
The TCP unit is called segment
- cat-snatcher 2y ago
  No it's called a slice.

mhandley 2y ago

RFC 791 which defines IP talks about both packets and datagrams. IP sends datagrams. Each IP datagram is fragmented into one or more packets depending on the underlying L2 network. But RFC 791 dates from when the underlying L2 network was most likely ARPAnet, which had 128 byte packets. Today the distinction is (or should be) moot - if you're relying on IP fragmentation to send your large IP datagram over multiple L2 packets, you're doing something wrong. IPv6 doesn't even support in-network fragmentation. In practice, the distinction has largely disappeared over time. Everyone I know talks about packets and very rarely bothers to distinguish between frames, datagrams and packets, because in practice one Ethernet frame generally carries one IP datagram, and everyone calls it a packet.

xnorswap 2y ago

Only on HN could someone implement networking from scratch, only to be dismissed by someone in the comments implying they've no idea what they're doing.

Angostura 2y ago
I think the comment was implying that they got word wrong, not that they had "no idea what they were doing". Bit overly dramatic
- xnorswap 2y ago
  The comment stated they got the word wrong, the implication is that it was out of ignorance. Yet the article uses frame throughout where technically correct, and what was important to the author wasn't that any frame was transmitted, but that they got their packet to show up correctly.
  - bigstrat2003 2y ago
    I certainly disagree that the implication you read into it was there. I read the statement as a friendly bit of banter, not an implied accusation of ignorance.
    - erinaceousjones 2y ago
      Only on HN could someone implement networking from scratch, only to be dismissed by friendly banter in the comments implying they've no idea what they're doing, only for that to be misinterpreted as actual criticism, only for an analysis to be done on this comment thread :-) only for dang to appear and ask us to stop being so meta. Also, in TFA the font is 3 pixels too far to the left and it made it literally unreadable for me
sitzkrieg 2y ago
talking to a chip over spi is not what id call scratch, lol

crest 2y ago

Smartass. Did you understand the title anyways?

donaldihunter 2y ago

For Ethernet, packets are a physical layer concept. They encapsulate frames which are a data link layer concept. https://en.wikipedia.org/wiki/Ethernet_frame https://en.wikipedia.org/wiki/Ethernet_frame