As a network option, subject to user and network service provider bilateral agreement, the Networkspecific facilities information element may be used to discriminate calls in a VPN context. The coding of this information element is shown in Figure 4-27. Some networks are known to have assigned the following network-specific coding for the field "Network-specific facility specification".
8 |
7 |
6 |
5 |
4 |
3 |
2 |
1 |
Octet |
ext. |
Facility coding value |
4 |
||||||
Spare |
Service parameters (IA5 characters) |
5, etc. |
||||||
Figure M.I.1/Q.931 – Example of Network-specific facilities information element coding to discriminate calls in a VPN context
Facility coding value (octet 4) |
|
Bits |
|
7 6 5 4 3 2 1 |
|
1 1 1 1 0 0 1 |
VPN service selection |
Service parameters (octet 5) |
|
Service parameters (e.g. CN identifier) may be encoded in octet(s) 5 according to the network service provider specifications. |
|