19 Jan
2018
19 Jan
'18
8:58 a.m.
On Jan 18, 2018, at 8:44 PM, William Herrin <bill@herrin.us> wrote:
Which packet? Is there a specific CDN that does this? I’d be curious to see data vs speculation.
Howdy,
Path MTU discovery (which sets the DF bit on TCP packets) is enabled by default on -every- operating system that's shipped for decades now. If you don't want it, you have to explicitly disable it. Disabling it for any significant quantity of traffic is considered antisocial since routers generally can't fragment in the hardware fast path.
I’m not seeing this in a PCAP capture to at least one CDN, either from my host or from the CDN endpoint. I suspect you’re mistaken. - Jared PCAP: https://puck.nether.net/~jared/akamai.pcap