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[quicwg/base-drafts] Resending ACK frames increases max_ack_delay unnecessarily (#1438)

janaiyengar <notifications@github.com> Mon, 11 June 2018 22:51 UTC

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Subject: [quicwg/base-drafts] Resending ACK frames increases max_ack_delay unnecessarily (#1438)
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Subodh notes that when a receiver simply resends old ACK frames, the ack_delay field keeps on increasing, which unnecessarily inflates max_ack_delay. From email thread:

<quote>
My concern is this situation: a "receiver" had not seen the original ACK (the packet was lost), then the sender rtos and sends a large ack delay to compensate for the rto, the max filter for max ack delay would inflate the delay for future packet. 

if latest_rtt - min_rtt  > ack_delay:

   max_ack_delay = max(max_ack_delay, ack_delay)

latest_rtt in this case would be rto_timer + rtt because the sender sends an ack after an rto. 
</quote>

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