Re: [LOOPS] BOF co-chairs thinking on LOOPS next steps

[Marie-Jose Montpetit <[e-mail]>]

Actually in FEC you do not process every packet. In what is called
“systematic mode” you send all the packets in the buffer (window) followed
by the coded packet(s). If everything goes well you never process anything.
And if something is lost then you use the recovery packets.


mjm

Marie-José Montpetit, Ph.D.
Research Affiliate, MIT Media Laboratory
[e-mail]
[e-mail]

On July 31, 2019 at 7:11:41 PM, Carsten Bormann ([e-mail]) wrote:

On Aug 1, 2019, at 00:18, Michael Welzl <[e-mail]> wrote:
>
> if the packet loss ratio is known

Conversely, retransmission can be better to handle random, bursty losses.
(For a definition of “better”, which may depend on your needs.)

But more importantly, for retransmission, the ingress node needs to store
copies of packets for a while (and retransmit from this cache), and the
egress node needs to send ACKs. This is much less work per packet than
doing FEC, which needs processing of the contents of each packet. So nodes
may be able to do retransmission LOOPS at a higher rate than they would be
able to do FEC LOOPS.

Grüße, Carsten

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