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I too was wondering how TCP and UDP can affect one another on the same interface and the explanation I read is that at the lowest level both UDP and TCP segment

I too was wondering how TCP and UDP can affect one another on the same interface and the explanation I read is that at the lowest level both UDP and TCP segment data into packets and place them onto the same network adapter's queue which can affect they way they are transmitted under congestion depending on the device/drivers.

wtallis 10y ago
That's not an explanation. That's just pointing in the general direction of where to look for an explanation.
- blackflame7000 10y ago
  Do you have a better explanation to offer because I'd love to learn? Not sure why I deserve a downvote for offering a potential solution when you with 6000 karma offer nothing.
  - wtallis 10y ago
    I think the claim was far too broad to actually be entirely true, and the evidence was both narrow and weak. The 1997 paper only shows that certain simulation parameters can produce bad packet loss for UDP traffic. But those parameters are almost all irrelevant to today's Internet: MTU is now 1500B not 512B, TCP congestion control is usually something like CUBIC rather than RENO, buffers are never a mere 16 packets long, and TCP traffic is more often relatively short-lived HTTP connections, not long-running FTP. The paper is just another piece of evidence that TCP synchronization sucks. You are very unlikely to encounter such perfect TCP synchronization on today's Internet, and even if you did, the dynamics of introducing some UDP flows to that situation would be different.
    - deleted 10y ago
      [deleted]
user5994461 10y ago
This makes no sense. UDP will drop data if there is congestion. Basically, if you care about congestion and data loss, you should not use UDP. --- If you do UDP and TCP. The UDP transfer will loose data during congestion, while the TCP transfer will slow down and try harder. This has some usage. For instance, videoconferences software will do TCP and UDP. The TCP is used for control data -low volume data that needs to work- (authentication/joining room/leaving/adjusting quality), the UDP is used for audio/video (some pieces may be lost during congestion, it's okay). If you use UDP for everything, you'll randomly loose control AND audio/video. It's the worst of both worlds. Not to be dismissive but I think the guy who gave you the advise doesn't really understand networking (or doesn't explain very well or was talking about some weird usage we don't know about).
- blackflame7000 10y ago
  Error checking can easily be added to udp for control data. Infact in IPv6 it's mandatory. At one moment you say udp will lose out, but we know tcp will back off on its reattempts exponentially based on the congestion window. Thus udp would win out. The argument wasn't that it was a significant impact, the argument is that they can cause interference.
  - user5994461 10y ago
    > the argument is that they can cause interference. UDP ignores everything else and always expect resources to be available for itself. We could say that UDP interferes with everything, we could say that everything interferes with UDP, it's both ways.
    - blackflame7000 10y ago
      Who chooses when a UDP packet is dropped? The freaking network adapter device driver which is what I said in the first place!
      - user5994461 10y ago

wtallis 10y ago

That's not an explanation. That's just pointing in the general direction of where to look for an explanation.

blackflame7000 10y ago
Do you have a better explanation to offer because I'd love to learn? Not sure why I deserve a downvote for offering a potential solution when you with 6000 karma offer nothing.
- wtallis 10y ago
  I think the claim was far too broad to actually be entirely true, and the evidence was both narrow and weak. The 1997 paper only shows that certain simulation parameters can produce bad packet loss for UDP traffic. But those parameters are almost all irrelevant to today's Internet: MTU is now 1500B not 512B, TCP congestion control is usually something like CUBIC rather than RENO, buffers are never a mere 16 packets long, and TCP traffic is more often relatively short-lived HTTP connections, not long-running FTP. The paper is just another piece of evidence that TCP synchronization sucks. You are very unlikely to encounter such perfect TCP synchronization on today's Internet, and even if you did, the dynamics of introducing some UDP flows to that situation would be different.
  - deleted 10y ago
    [deleted]

user5994461 10y ago

This makes no sense. UDP will drop data if there is congestion. Basically, if you care about congestion and data loss, you should not use UDP. --- If you do UDP and TCP. The UDP transfer will loose data during congestion, while the TCP transfer will slow down and try harder. This has some usage. For instance, videoconferences software will do TCP and UDP. The TCP is used for control data -low volume data that needs to work- (authentication/joining room/leaving/adjusting quality), the UDP is used for audio/video (some pieces may be lost during congestion, it's okay). If you use UDP for everything, you'll randomly loose control AND audio/video. It's the worst of both worlds. Not to be dismissive but I think the guy who gave you the advise doesn't really understand networking (or doesn't explain very well or was talking about some weird usage we don't know about).

blackflame7000 10y ago
Error checking can easily be added to udp for control data. Infact in IPv6 it's mandatory. At one moment you say udp will lose out, but we know tcp will back off on its reattempts exponentially based on the congestion window. Thus udp would win out. The argument wasn't that it was a significant impact, the argument is that they can cause interference.
- user5994461 10y ago
  > the argument is that they can cause interference. UDP ignores everything else and always expect resources to be available for itself. We could say that UDP interferes with everything, we could say that everything interferes with UDP, it's both ways.
  - blackflame7000 10y ago
    Who chooses when a UDP packet is dropped? The freaking network adapter device driver which is what I said in the first place!
    - user5994461 10y ago