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;