[c-nsp] Products for dealing with packet re-ordering?

[Saku Ytti]

Hey Alex,

The daemon is not exaggerated, but it's also not inherent problem to
TCP. TCP inherently guarantees correct order, so reordering isn't an
issue to TCP on itself. Over time we've noticed that networks are
lossy but retain order, so we've tinkered with TCP algorithms so that
it has become very adapt in dealing with packet loss but at the time
wholly dependent on network keeping order, as misorder is immediately
interpreted by common TCP algorithms to imply a packet loss, so resend
is requested.

If you control both ends already, you could just change TCP algorithm
to one which tolerates reordering and all would be well. There is also
somewhat accidental light at the end of the tunnel, due to various
inefficiencies, including being too aggressive and bursting during
window growth lot of the content shops are looking to change to new
TCP algorithm called BBR, it just so happens it'll be more tolerant to
reordering as it's somewhat different in detecting packet loss.


On 9 January 2018 at 17:51, Alex K. <nsp.lists at gmail.com> wrote:
> Hello everyone,
>
> An interesting issue came across my desk, one I'd like to hear community
> opinion about.
>
> A customer of mine, due to carrier restrictions, is about to aggregate a
> few links into one (using etherchannel). Due to required bandwidth, it
> seems he would need to load balance across the LAG on a packet by packet
> basis. Now, we all know the dangers of packet reordering. On another hand,
> there are products from VeloCloud, Talari, SilverPeak and probably many
> others, that on paper are capable of dealing with the issues and delivering
> packets in orderly manner.
>
> The question is, is anybody using those products and can admit first-hand
> experience? Or the daemon of packet reordering is grossly exaggerated?
>
> Thank you for sharing your experience/opinions on the matter.
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  ++ytti