The sequence of AS path segments.
Each AS path segment is represented by a triple <TYPE, LENGTH, VALUE>.
The TYPE is a 1-octet field which has two possible values:
(1) AS_SET : unordered set of ASs a route in the UPDATE message
has traversed.
(2) AS_SEQUENCE : ordered set of ASs a route in the UPDATE message
has traversed.
The LENGTH is a 1-octet field containing the number of ASs in
the value field.
The VALUE field contains one or more AS numbers, each AS is
represented in the octet string as a pair of octets according to
the following algorithm:
first-byte-of-pair = ASNumber / 256;
second-byte-of-pair = ASNumber & 255;