Handshake Extension Message: Packet Filter

[maxsharabayko]

The Packet Filter Handshake Extension section is missing.
Please fill using the following format:

#### Packet Filter Extension
~~~
0                   1                   2                   3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|                           Field01                            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|     Field    |     Field     |             Field              |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
~~~
{: #fig-hsext-packet-filter title="Packet Filter Extension Message"}

Field01 (32 bits):
: This field ...

[ethouris]

Let me try to consolidate the minimum text required for the Packet Filter and FEC.

1. Field network syntax: identical as for Socket ID.

2. Packet Filter configuration syntax (string formatting):

There are two levels:

A. Packet Filter configuration syntax in general

How this string is interpreted depends on the filter itself. However, there is an obligatory
general syntax:

<filter-type>,<key>:<value>[,...]

The parts of this syntax are separated by commas. The first part is the name of
the filter. This is followed by one or more key:value pairs, the interpretation
of which depends on the filter type.

B. Keys used for "fec" filter type

• cols: The number of columns in your FEC matrix (which is the equivalent of
  the size of each row). This parameter is obligatory and must be a positive
  number >=2.

• rows: The number of rows in your FEC matrix (which is the equivalent of
  the size of each column). This parameter is optional and defaults to 1. If the
  value is >=2, this corresponds to the exact number of rows. Beside this, two
  other special cases are allowed:

  • 1: in this case you have a row-only configuration (no columns)

  • -N (where N >= 2): column-only configuration. In this case N designates
    the exact size of a column, but the FEC control packet for rows will not be
    generated (in other words, the cols parameter designates in this case only
    a number of columns in one series)

• layout: The format of the FEC matrix. The possible values are:

  • even: block aligned (default) - columns are arranged in a solid matrix;
    the first sequence numbers (SNbase) are all contained in one row.

  • staircase: non-block aligned - column starting points are staggered;
    the first sequence numbers (SNbase) have an offset equivalent to R+1.

• arq: Optional use of the Automatic Repeat Request (ARQ) protocol. The
  possible values are:

  • always: ARQ is done in parallel with FEC (a loss is always reported
    immediately once detected in SRT).

  • onreq: ARQ is allowed, but a loss is only reported when FEC fails to
    rebuild, at the moment when an incoming packet has a sequence number that
    exceeds the last in one of the column groups; such a packet, if still lacking
    at that moment, is considered no longer recoverable by FEC.

  • never: ARQ is not done at all. Packets not recovered by FEC undergo
    TLPKTDROP, just like those that fail ARQ recovery in a conventional SRT
    exchange.