LINKTYPE_NG40

Packet structure

+---------------------------+
|            Type           |
|         (4 Octets)        |
+---------------------------+
|           Length          |
|         (4 Octets)        |
+---------------------------+
|          Protocol         |
|         (4 Octets)        |
+---------------------------+
|             ID            |
|         (4 Octets)        |
+---------------------------+
|            Flags          |
|         (4 Octets)        |
+---------------------------+
|   Subheaders and payload  |
.                           .
.                           .
.                           .

Description

All multi-byte fields are in network byte order (big-endian).

The type field contains a value that is one of:

  • 2, if the payload is ATM AAL2 traffic;
  • 3, if the payload is ATM AAL5 traffic;
  • 4, if the payload is Iub-over-UDP-over-IPv4 traffic;
  • 5, if the payload is Iub-over-SCTP-over-IPv4 traffic;
  • 6, if the payload is Iub-over-UDP-over-IPv6 traffic;
  • 7, if the payload is Iub-over-SCTP-over-IPv6 traffic.

The length field gives the length of the entire packet, including the five header fields.

The protocol field contains a value that specifies the protocol running atop the SSCOP protocol layer. The value is one of:

  • 1, if the subprotocol is ALCAP;
  • 2, if the subprotocol is NBAP.

The ID field gives a "call ID" indicating to which call the packet pertains.

The flags field contains the following flags:

  • 0x00000001 - the message is ciphered

The form of the subheader following the header depends on the value in the type field.

Subheaders

For ATM AAL2 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|            VPI            |
|         (2 Octets)        |
+---------------------------+
|            VCI            |
|         (2 Octets)        |
+---------------------------+
|            CID            |
|         (2 Octets)        |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message;
  • 2, if the content is a message from NodeB to the Radio Network Controller (up-link message);
  • 3, if the content is a message from the Radio Network Controller to NodeB (down-link message).

The VPI and VCI identify the ATM virtual circuit.

The CID is a channel identifier that identifies the user of the virtual circuit.

For ATM AAL5 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|            VPI            |
|         (2 Octets)        |
+---------------------------+
|            VCI            |
|         (2 Octets)        |
+---------------------------+
|          Padding          |
|         (2 Octets)        |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message;
  • 2, if the content is a message from NodeB to the Radio Network Controller (up-link message);
  • 3, if the content is a message from the Radio Network Controller to NodeB (down-link message).

The VPI and VCI identify the ATM virtual circuit.

For Iub-over-UDP-over-IPv4 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|         Local port        |
|         (2 Octets)        |
+---------------------------+
|     Local IPv4 address    |
|         (4 Octets)        |
+---------------------------+
|        Remote port        |
|         (2 Octets)        |
+---------------------------+
|          Padding          |
|         (2 Octets)        |
+---------------------------+
|    Remote IPv4 address    |
|         (4 Octets)        |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message;
  • 2, if the content is a message from NodeB to the Radio Network Controller (up-link message);
  • 3, if the content is a message from the Radio Network Controller to NodeB (down-link message).

The IPv4 addresses and UDP ports identify the endpoints of the path.

For Iub-over-SCTP-over-IPv4 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|         Local port        |
|         (2 Octets)        |
+---------------------------+
|     Local IPv4 address    |
|         (4 Octets)        |
+---------------------------+
|        Remote port        |
|         (2 Octets)        |
+---------------------------+
|          Padding          |
|         (2 Octets)        |
+---------------------------+
|    Remote IPv4 address    |
|         (4 Octets)        |
+---------------------------+
|       SCTP stream ID      |
|         (4 Octets)        |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message.

The IPv4 addresses and SCTP ports identify the endpoints of the path; the SCTP stream ID identifies the SCTP stream of the path.

For Iub-over-UDP-over-IPv6 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|         Local port        |
|         (2 Octets)        |
+---------------------------+
|     Local IPv6 address    |
|         (16 Octets)       |
+---------------------------+
|        Remote port        |
|         (2 Octets)        |
+---------------------------+
|    Remote IPv6 address    |
|         (16 Octets)       |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message;
  • 2, if the content is a message from NodeB to the Radio Network Controller (up-link message);
  • 3, if the content is a message from the Radio Network Controller to NodeB (down-link message).

The IPv6 addresses and UDP ports identify the endpoints of the path.

For Iub-over-SCTP-over-IPv6 traffic, the subheader is of the form:

+---------------------------+
|         Direction         |
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (1 Octet)         |
+---------------------------+
|         Local port        |
|         (2 Octets)        |
+---------------------------+
|     Local IPv6 address    |
|         (16 Octets)       |
+---------------------------+
|        Remote port        |
|         (2 Octets)        |
+---------------------------+
|    Remote IPv6 address    |
|         (16 Octets)       |
+---------------------------+
|       SCTP stream ID      |
|         (4 Octets)        |
+---------------------------+

The direction field contains a value that is one of:

  • 0, if the packet is a received message;
  • 1, if the packet is a transmitted message;
  • 2, if the content is a message from NodeB to the Radio Network Controller (up-link message);
  • 3, if the content is a message from the Radio Network Controller to NodeB (down-link message).

The IPv6 addresses and SCTP ports identify the endpoints of the path; the SCTP stream ID identifies the SCTP stream of the path.

Payload

For AAL2, UDP-over-IPv4, and UDP-over-IPv6 traffic, context information for the Frame Protocol and for the RLC/MAC layer is provided following the subheader.

The Frame Protocol context information is of the form:

+----------------------------------+
|         Network Interface        |
|             (1 Octet)            |
+----------------------------------+
|              Division            |
|             (1 Octet)            |
+----------------------------------+
|              Release             |
|             (1 Octet)            |
+----------------------------------+
|              Padding             |
|             (1 Octet)            |
+----------------------------------+
|            Release year          |
|             (2 Octets)           |
+----------------------------------+
|           Release month          |
|             (1 Octet)            |
+----------------------------------+
|     Uplink/Downlink indicator    |
|             (1 Octet)            |
+----------------------------------+
|               Padding            |
|             (2 Octets)           |
+----------------------------------+
|            Channel type          |
|             (4 Octets)           |
+----------------------------------+
|     DCH CRC-present indicator    |
|             (1 Octet)            |
+----------------------------------+
|               Padding            |
|             (3 Octets)           |
+----------------------------------+
|         Paging indications       |
|             (4 Octets)           |
+----------------------------------+
|           Channel count          |
|             (4 Octets)           |
+----------------------------------+
|          E-DCH DDI count         |
|             (4 Octets)           |
+----------------------------------+
|            E-DCH type            |
|             (1 Octet)            |
+----------------------------------+
|          HS-DSCH entity          |
|             (1 Octet)            |
+----------------------------------+
|  Channel information structures  |
.                                  .
.                                  .
.                                  .
|                                  |
+----------------------------------+
| E-DCH DDI information structures |
.                                  .
.                                  .
.                                  .
|                                  |
+----------------------------------+

The network interface field contains a value that is one of:

  • 0, if the traffic is from the Iub interface;
  • 1, if the traffic is from the Iur interface.

The division field contains a value that is one of:

  • 0, if the air interface is using FDD;
  • 1, if the air interface is using 3.84 Mchips/s TDD;
  • 2, if the air interface is using 1.28 Mchips/s TDD;
  • 3, if the air interface is using 7.68 Mchips/s TDD.

The release field gives the release number for the version of the frame protocol.

The release year field gives the release year numbe for the version of the frame protocol.

The release month field gives the release month number (1 = January, 12 = December) for the version of the frame protocol.

The uplink/downlink indicator is 0 for messages sent from the Radio Network Controller (RNC) to NodeB and 1 for messages sent from NodeB to the RNC.

The channel type field contains a value that is one of:

  • 1, if the traffic is on the Random Access Channel (RACH) using FDD;
  • 2, if the traffic is on the RACH using TDD;
  • 3, if the traffic is on the Forward Access Channel (FACH) for the Iub interface using FDD;
  • 4, if the traffic is on the FACH for the Iub interface using TDD;
  • 5, if the traffic is on the Downlink Shared Channel (DSCH) for the Iub interface using FDD;
  • 6, if the traffic is on the DSCH for the Iub interface using TDD;
  • 8, if the traffic is on the Uplink Shared Channel (USCH) using 3.84 Mchips/s TDD;
  • 24, if the traffic is on the USCH using 1.28 Mchips/s TDD;
  • 9, if the traffic is on the Paging Channel (PCH);
  • 10, if the traffic is on the Common Packet Channel (CPCH);
  • 11, if the traffic is on the Broadcast Channel (BCH);
  • 12, if the traffic is on a Dedicated Channel (DCH);
  • 13, if the traffic is on the High Speed Downlink Shared Channel (HS-DSCH);
  • 15, if the traffic is on the FACH for the Iur interface;
  • 16, if the traffic is on the DSCH for the Iur interface;
  • 17, if the traffic is on an Enhanced Uplink Dedicated Channel (E-DCH);
  • 18, if the traffic is on the RACH using 1.28 Mchips/s TDD.

The DCH CRC-present indicator is 0 if the CRC for DCHes and E-DCHes is absent and 1 if it's present.

The paging indications field is 0 if there is a no-paging indication bitmap in the payload and 1 if there's a paging indication bitmap in the payload.

The E-DCH type field is always 0.

The HS-DSCH entity field contains a value that is one of:

  • 0, if the entity is not defined;
  • 1, if the traffic is an HS entity;
  • 2, if the traffic is an EHS entity.

The array of channel information structures has the number of channel information structure elements specified by the channel count field. A channel information structure is of the form:

+------------------------------------------------+
| Number of transmitted RLC/MAC transport blocks |
|                   (4 Octets)                   |
+------------------------------------------------+
|   Size of transmitted RLC/MAC transport blocks |
|                   (4 Octets)                   |
+------------------------------------------------+

The number of transmitted RLC/MAC transport blocks is the number of such blocks in the Frame Protocol payload for the channel if the channel is not an E-DCH.

The size of transmitted RLC/MAC transport blocks is the size, in bits, of all such blocks in the Frame Protocol payload for the channel if the channel is not an E-DCH.

The array of E-DCH DDI information structures has the number of E-DCH DDI information structure elements specified by the E-DCH DDI count field. An E-DCH DDI information structure is of the form:

+---------------------------+
| Data Description Indicator|
|         (1 Octet)         |
+---------------------------+
|          Padding          |
|         (3 Octets)        |
+---------------------------+
|        MAC PDU size       |
|         (4 Octets)        |
+---------------------------+

The Data Description Indicator contains a value as specified by 3GPP TS 25.321.

The RLC/MAC layer context information is of the form:

+---------------------------+
|           U-RNTI          |
|         (4 Octets)        |
+---------------------------+
|            CTMUX          |
|          (1 Octet)        |
+---------------------------+
|           Content         |
|          (1 Octet)        |
+---------------------------+
|             Mode          |
|          (1 Octet)        |
+---------------------------+
|       Radio bearer ID     |
|          (1 Octet)        |
+---------------------------+
|     Ciphering indicator   |
|          (1 Octet)        |
+---------------------------+
|    Deciphered indicator   |
|          (1 Octet)        |
+---------------------------+
|          Padding          |
|         (2 Octets)        |
+---------------------------+

There are 64 RLC/MAC layer context information structures in sequence; the number of valid structures is specified by the channel count field - all structures following the last valid structure should be ignored.

The U-RNTI field is the UTRAN Radio Network Temporary Identifier for the user equipment.

The CTMUX field is 0 if the channel is not multiplexed and 1 if the channel is multiplexed.

The content field indicates the type of RLC channel carrying the content; its value is one of:

  • 0, if the content is for an unknown type of channel;
  • 1, if the content is for a Dedicated Control Channel (DCCH);
  • 2, if the content is for a Packet Switched (PS) Dedicated Traffic Channel (DTCH);
  • 3, if the content is for a Circuit Switched (CS) DTCH.

The mode field contains a value that specifies the mode used for the RLC sublayer; it is one of:

  • 0 for Transparent mode;
  • 1 for Unacknowledged mode;
  • 2 for Acknowledged mode.

The radio bearer id (RBID) contains a value used by the network elements at the Iub interface to refer a radio bearer.

The ciphering indicator is 0 if the payload is ciphered and 1 if it is ciphered.

The deciphered indicator is 0 if the payload has not been deciphered and 1 if it has been deciphered.

The payload follows the RLC/MAC context information structures. The payload consists of frames for the Frame Protocol as specified by 3GPP TS 25.427 for dedicated channels and 3GPP TS 25.435 for common/shared channels.

For AAL5 traffic, an SSCOP packet, as specified by ITU-T Recommendation Q.2110, follows the subheader. Whether ALCAP or NBAP is carried inside SSCOP is specified by the protocol field in the header.

For SCTP-over-IPv4 and SCTP-over-IPv6, an NBAP packet follows the subheader.