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RFC 6846, "RObust Header Compression (ROHC): A Profile for TCP/IP (ROHC-TCP)", January 2013

Source of RFC: IETF - NON WORKING GROUP
Area Assignment: tsv

Errata ID: 3724
Status: Rejected
Type: Technical
Publication Format(s) : TEXT

Reported By: Raj Kumar
Date Reported: 2013-09-12
Rejected by: Martin Stiemerling
Date Rejected: 2013-09-20

Section 8.2 says:

tcp_opt_eol(nbits)
{
UNCOMPRESSED {
type =:= uncompressed_value(8, 0) [ 8 ];
padding =:=
uncompressed_value(nbits-8, 0) [ nbits-8 ];
}
CONTROL {
pad_len [ 8 ];
}
COMPRESSED eol_list_item {
pad_len =:= compressed_value(8, nbits-8) [ 8 ];
}
COMPRESSED eol_irregular {
pad_len =:= static;
ENFORCE(nbits-8 == pad_len.UVALUE);
}
}

It should say:

tcp_opt_eol(nbits)
{
UNCOMPRESSED {
type =:= uncompressed_value(8, 0) [ 8 ];
padding =:=
uncompressed_value(nbits-8, 0) [ nbits-8 ];
}
CONTROL {
pad_len [ 8 ];
}
COMPRESSED eol_list_item {

}
pad_len can be calculated at De compressor by following formula
pad_len = 4 -(length of uncompressed header formed till EOL byte % 4)

COMPRESSED eol_irregular {
pad_len =:= static;
ENFORCE(nbits-8 == pad_len.UVALUE);
}
}

Notes:

pad_len has the potential to become Inferred field, by doing this we can save one byte in compressed header and can effectively increase the compression efficiency.
--VERIFIER NOTES--
Rejected, as this is not an errata, as the 'corrected text' is in fact a change to the formal definition of the header formats.

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