Section: 21.2 Home Agent – Access Point Name (HA-APN) 21.2.1 General
Content: The HA-APN is composed of two parts as follows: - The HA-APN Network Identifier; this defines to which external network the HA is connected. - The HA-APN Operator Identifier; this defines in which PLMN the HA serving the HA-APN is located. The HA-APN Operator Identifier is placed after the HA-APN Network Identifier. The HA-APN consisting of both the Network Identifier and Operator Identifier corresponds to a FQDN of a HA; the HA-APN has, after encoding as defined in the paragraph below, a maximum length of 100 octets. The encoding of the HA-APN shall follow the Name Syntax defined in IETF RFC 2181 [18], IETF RFC 1035 [19] and IETF RFC 1123 [20]. The HA-APN consists of one or more labels. Each label is coded as a one octet length field followed by that number of octets coded as 8 bit ASCII characters. Following IETF RFC 1035 [19] the labels shall consist only of the alphabetic characters (A-Z and a-z), digits (0-9) and the hyphen (-). Following IETF RFC 1123 [20], the label shall begin and end with either an alphabetic character or a digit. The case of alphabetic characters is not significant. The HA-APN is not terminated by a length byte of zero. For the purpose of presentation, a HA-APN is usually displayed as a string in which the labels are separated by dots (e.g. "Label1.Label2.Label3").