On Sat, Jun 21, 2025 at 12:38 PM chia-yu.chang@nokia-bell-labs.com wrote:
From: Chia-Yu Chang chia-yu.chang@nokia-bell-labs.com
As SACK blocks tend to eat all option space when there are many holes, it is useful to compromise on sending many SACK blocks in every ACK and attempt to fit the AccECN option there by reducing the number of SACK blocks. However, it will never go below two SACK blocks because of the AccECN option.
As the AccECN option is often not put to every ACK, the space hijack is usually only temporary. Depending on the length of AccECN option (can be either 11, 8, 5, or 2 bytes, cf. Table 5 in AccECN spec) and the NOPs used for alignment of other TCP options, up to two SACK blocks will be reduced.
I think it would be nice to study how AccECN and SACK compression play together ?