Outer Header Creation
Per 3GPP TS 29.244 v16.4.0, the Outer Header Creation Description field, when present, is encoded as specified in following table. It takes the form of a bitmask where each bit indicates the outer header to be created in the outgoing packet. Spare bits are ignored by the receiver.
Octet / Bit | Outer Header Created in the Outgoing Packet |
---|---|
5/1 | GTP-U/UDP/IPv4 |
5/2 | GTP-U/UDP/IPv6 |
5/3 | UDP/IPv4 |
5/4 | UDP/IPv6 |
5/5 | IPv4 |
5/6 | IPv6 |
5/7 | C-TAG |
5/8 | S-TAG |
6/1 | N19 Indication |
6/2 | N6 Indication |
6/3 | TCP/IPv4 |
6/4 | TCP/IPv6 |
NOTE:
-
Currently, the UP/UPF doesn't support the following values of Outer Header Creation Description:
-
IPv4
-
IPv6
-
C-TAG
-
S-TAG
-
N19 Indication
-
N6 Indication
-
-
Third and fourth bits of sixth Octet (that is, 6/3 and 6/4) are spare bits (that is, not part of 3GPP TS) used for LI over TCP.
Important | If SMF/CP uses older version for Outer Header Creation, then undefined behavior (including crashes) can be seen. |