4 ms·

AWS de-prioritizes UDP packets making it not a great choice for UDP based applications as well.

by kerr23 11y ago

akent 11y ago
Do you have a reference or a link for this?
- kerr23 11y ago
  AWS is always super closed mouthed about their infrastructure. The info I have came from a conversation with an AWS Solutions Architect. It's a couple of years old, but based on my experience it's still true today.
majke 11y ago
That doesn't sound right. Consider DNS.
- dfc 11y ago
  Whenever people talk about behavior/treatment of UDP traffic I consider DNS as a special case. I have no idea how AWS handles UDP but I will never use DNS as a generalizable example of UDP traffic.
- cbsmith 11y ago
  At least in the past, it really was true. I've been burned by this before using UDP in AWS. In AWS, I've learned to be skeptical of using protocols other than TCP. That said, it consequently has been a long time since I've tested UDP over AWS.
- kerr23 11y ago
  DNS was precisely the area where we got bit by it. We were using a Non-AWS DNS resolver (aka Google) and we would often get dns resolution errors despite our NAT not being remotely taxed by the traffic.
cbsmith 11y ago
Yeah, I've run in to this. The point about NAT makes me wonder though if it is really de-prioritization or just the network straining to handle all that recalculation of checksums.
- api 11y ago
  It's legal to send UDP packets with a zero checksum, indicating "no checksum." This can be set at a UDP socket level in Linux. I wonder if that would make any difference? (Of course this assumes your protocol has some alternate method of verifying transferred data, which many do.)
  - cbsmith 11y ago
    That is an interesting idea. I'd love to see an experiment to determine if it makes a difference.
    - api 11y ago
      Example: https://github.com/zerotier/ZeroTierOne/blob/14264c2d6f7d20b15081a1db5e8ca4b978d935a0/osdep/Phy.hpp#L303 https://github.com/zerotier/ZeroTierOne/blob/14264c2d6f7d20b...

AWS de-prioritizes UDP packets making it not a great choice for UDP based applications as well.

by kerr23 11y ago

AWS de-prioritizes UDP packets making it not a great choice for UDP based applications as well.

akent 11y ago

Do you have a reference or a link for this?

kerr23 11y ago
AWS is always super closed mouthed about their infrastructure. The info I have came from a conversation with an AWS Solutions Architect. It's a couple of years old, but based on my experience it's still true today.

majke 11y ago

That doesn't sound right. Consider DNS.

dfc 11y ago
Whenever people talk about behavior/treatment of UDP traffic I consider DNS as a special case. I have no idea how AWS handles UDP but I will never use DNS as a generalizable example of UDP traffic.
cbsmith 11y ago
At least in the past, it really was true. I've been burned by this before using UDP in AWS. In AWS, I've learned to be skeptical of using protocols other than TCP. That said, it consequently has been a long time since I've tested UDP over AWS.
kerr23 11y ago
DNS was precisely the area where we got bit by it. We were using a Non-AWS DNS resolver (aka Google) and we would often get dns resolution errors despite our NAT not being remotely taxed by the traffic.

cbsmith 11y ago

Yeah, I've run in to this. The point about NAT makes me wonder though if it is really de-prioritization or just the network straining to handle all that recalculation of checksums.

api 11y ago
It's legal to send UDP packets with a zero checksum, indicating "no checksum." This can be set at a UDP socket level in Linux. I wonder if that would make any difference? (Of course this assumes your protocol has some alternate method of verifying transferred data, which many do.)
- cbsmith 11y ago
  That is an interesting idea. I'd love to see an experiment to determine if it makes a difference.
  - api 11y ago
    Example: https://github.com/zerotier/ZeroTierOne/blob/14264c2d6f7d20b15081a1db5e8ca4b978d935a0/osdep/Phy.hpp#L303 https://github.com/zerotier/ZeroTierOne/blob/14264c2d6f7d20b...