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Dealing with IPv6 fragmentation in the DNS

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Re: Dealing with IPv6 fragmentation in the DNS

#4

Post by pilif »

dom0 wrote: post #3

Maybe we should bow to the inevitable and recognise that IPv6 is an unfixable problem.

if it's unfixable, why is 40% of our in-office internet traffic running over IPv6? Why is 100% of our LAN traffic over IPv6? Why is 30% of the traffic to our sites running over IPv6?

Re: Dealing with IPv6 fragmentation in the DNS

#5

Post by majke »

pilif wrote: post #4
dom0 wrote: post #3

Maybe we should bow to the inevitable and recognise that IPv6 is an unfixable problem.

if it's unfixable, why is 40% of our in-office internet traffic running over IPv6? Why is 100% of our LAN traffic over IPv6? Why is 30% of the traffic to our sites running over IPv6?

The article suggests "Fragmentation in IPv6 is unfixable", not ipv6 itself. Try running this to see if fragments get delivered to you:

http://icmpcheckv6.popcount.org

http://icmpcheck.popcount.org (IPv4 version)

via: https://blog.cloudflare.com/ip-fragmentation-is-broken/

Re: Dealing with IPv6 fragmentation in the DNS

#6

Post by heinrich5991 »

majke wrote: post #5
pilif wrote: post #4

Earlier quoted context omitted.

if it's unfixable, why is 40% of our in-office internet traffic running over IPv6? Why is 100% of our LAN traffic over IPv6? Why is 30% of the traffic to our sites running over IPv6?

The article suggests "Fragmentation in IPv6 is unfixable", not ipv6 itself. Try running this to see if fragments get delivered to you: http://icmpcheckv6.popcount.org http://icmpcheck.popcount.org (IPv4 version) via: https://blog.cloudflare.com/ip-fragmentation-is-broken/

Seems to work for me (?).

Re: Dealing with IPv6 fragmentation in the DNS

#7

Post by vidarh »

majke wrote: post #5
pilif wrote: post #4

Earlier quoted context omitted.

if it's unfixable, why is 40% of our in-office internet traffic running over IPv6? Why is 100% of our LAN traffic over IPv6? Why is 30% of the traffic to our sites running over IPv6?

The article suggests "Fragmentation in IPv6 is unfixable", not ipv6 itself. Try running this to see if fragments get delivered to you: http://icmpcheckv6.popcount.org http://icmpcheck.popcount.org (IPv4 version) via: https://blog.cloudflare.com/ip-fragmentation-is-broken/

Works great for me on my laptop. I don't doubt for a second that there are problems (my phone doesn't get ipv6 at all and one of the ipv4 tests failed... but mobile networks are notorious when it comes to filtering traffic), but "unfixable"?

Re: Dealing with IPv6 fragmentation in the DNS

#8

Post by the8472 »

> IPv6 Extension Headers require any transport protocol-sensitive functions in network switches to unravel the packet header’s extension header chain. This takes a variable number of cycles for the device and furthermore requires that the switch should recognise all the extension headers encountered on the header chain. This is anathema to a switch, in so far as it entails a variable amount of time to process.

If it is so much anathema to their nature then maybe they shouldn't insist on violating network layers?

Re: Dealing with IPv6 fragmentation in the DNS

#9

Post by stephengillie »

Having a variable header complicates Cut-Through switching[0], which forwards the entire frame just after the switch gets the destination field of the header.

This sounds like it would force a return to Store-And-Forward[1], where the switch waits for the entire frame to load into memory, before forwarding to its next hop. Waiting these few milliseconds doesn't sound bad, until you consider that's added to each packet, reducing (e.g.) application performance.

[0] https://en.wikipedia.org/wiki/Cut-through_switching

[1] https://en.wikipedia.org/wiki/Store_and_forward

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