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Protocol Configuration Options

Protocol Configuration Options (PCO) is a component of NAS message and this component can be carried by many different messages as follows.

• PDN Connectivity Request
• ActivateDefaultEPSBearerContextRequest
• ActivateDefaultEPSBearerContextAccept

Data Structure of PCO is very flexible (complicated) which may give a lot of difficulties in message decoding process. The structure is as follows.

There are various Container ID as shown below. The list would get longer and longer as specification evolves.

Example 1 : 271B80802110030000108106C0A801028306C0A80102000D04C0A80102

Octet 1 (Protocol Configuration Option IEI): 27H

Octet 2 (Length of protocol configuration options contents): 1BH=27

Octet 3 : 80H = 10000000b

ext = 1

spare = 0000

Configuration Protocol = 000

Octet 4-253 : 802110030000108106C0A801028306C0A80102000D04C0A80102

Protocol ID 1 : 8021H (IPCP)

Length of Protocol ID 1 Contents : 10H=16

Protocol ID 1 Contents = 030000108106C0A801028306C0A80102H

Protocol ID 2 : 0004H(DNS)

Length of Protocol ID 2 Contents : 04H=4

Protocol ID 2 Contents = C0A80102H

How Network Configure PCO ?

The simplest answer is "It is completely up to Network !", but one common scenario is "It sends whatever requested by PCO from UE" as shown below.

i) UE --> NW : PCO in PDN Connectivity Request (UE request the information it want to get)

ii) UE <-- NW : PCO in Activate Default EPS Bearer Request (NW informs UE of what it want)

< Example 1 >

In this example, what NW sends in PCO matches exactly what UE requested in PCO

Protocol Configuration Options - in PDN Connectivity Request

   Element ID: 0x27

   Length: 26

   [Link direction: MS to network (0)]

   1... .... = Extension: True

   Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

   Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

       Length: 0x10 (16)

       PPP IP Control Protocol

           Code: Configuration Request (1)

           Identifier: 0 (0x00)

           Length: 16

           Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

               Primary DNS Server IP Address: 0.0.0.0

                   Type: Primary DNS Server IP Address (129)

                   Length: 6

                   Primary DNS Address: 0.0.0.0 (0.0.0.0)

               Secondary DNS Server IP Address: 0.0.0.0

                   Type: Secondary DNS Server IP Address (131)

                   Length: 6

                   Secondary DNS Address: 0.0.0.0 (0.0.0.0)

   Protocol or Container ID: DNS Server IPv4 Address Request (0x000d)

       Length: 0x00 (0)

   Protocol or Container ID: IP address allocation via NAS signalling (0x000a)

       Length: 0x00 (0)

Protocol Configuration Options - in Activate Default EPS Bearer Request

    Element ID: 0x27

    Length: 27

    [Link direction: Network to MS (1)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

        Length: 0x10 (16)

        PPP IP Control Protocol

            Code: Configuration Nak (3)

            Identifier: 0 (0x00)

            Length: 16

            Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

                Primary DNS Server IP Address: 192.168.1.2

                    Type: Primary DNS Server IP Address (129)

                    Length: 6

                    Primary DNS Address: 192.168.1.2 (192.168.1.2)

                Secondary DNS Server IP Address: 192.168.1.2

                    Type: Secondary DNS Server IP Address (131)

                    Length: 6

                    Secondary DNS Address: 192.168.1.2 (192.168.1.2)

    Protocol or Container ID: DNS Server IPv4 Address (0x000d)

        Length: 0x04 (4)

        IPv4: 192.168.1.2

< Example 2 >

In this example, what NW sends in PCO matches roughly what UE requested in PCO, but in detail some of the information (e.g, CSCF IPv6 address) is missing. However, UE may accept this.

Protocol Configuration Options - in PDN Connectivity Request

    Element ID: 0x27

    Length: 35

    [Link direction: MS to network (0)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

        Length: 0x10 (16)

        PPP IP Control Protocol

            Code: Configuration Request (1)

            Identifier: 0 (0x00)

            Length: 16

            Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

                Primary DNS Server IP Address: 0.0.0.0

                    Type: Primary DNS Server IP Address (129)

                    Length: 6

                    Primary DNS Address: 0.0.0.0 (0.0.0.0)

                Secondary DNS Server IP Address: 0.0.0.0

                    Type: Secondary DNS Server IP Address (131)

                    Length: 6

                    Secondary DNS Address: 0.0.0.0 (0.0.0.0)

    Protocol or Container ID: DNS Server IPv4 Address Request (0x000d)

        Length: 0x00 (0)

    Protocol or Container ID: DNS Server IPv6 Address Request (0x0003)

        Length: 0x00 (0)

    Protocol or Container ID: P-CSCF IPv6 Address Request (0x0001)

        Length: 0x00 (0)

    Protocol or Container ID: P-CSCF IPv4 Address Request (0x000c)

        Length: 0x00 (0)

Protocol Configuration Options - in Activate Default EPS Bearer Request

    Element ID: 0x27

    Length: 15

    [Link direction: Network to MS (1)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

        Length: 0x04 (4)

        PPP IP Control Protocol

            Code: Configuration Nak (3)

            Identifier: 0 (0x00)

            Length: 4

    Protocol or Container ID: P-CSCF IPv4 Address (0x000c)

        Length: 0x04 (4)

        IPv4: 192.168.137.1

< Example 3 >

Protocol Configuration Options - in PDN Connectivity Request

NAS EPS session management messages: PDN connectivity request (0xd0)

 0001 .... = PDN type: IPv4 (1)

 .... 0001 = Request type: initial request (1)

 ESM information transfer flag

     1101 .... = Element ID: 0xd-

     .... 000. = Spare bit(s): 0x00

     .... ...1 = EIT (ESM information transfer): Security protected ESM information transfer required

 Protocol Configuration Options

     Element ID: 0x27

     Length: 29

     [Link direction: MS to network (0)]

     1... .... = Extension: True

     Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

     Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

         Length: 0x10 (16)

         PPP IP Control Protocol

             Code: Configuration Request (1)

             Identifier: 0 (0x00)

             Length: 16

             Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

                 Primary DNS Server IP Address: 0.0.0.0

                     Type: Primary DNS Server IP Address (129)

                     Length: 6

                     Primary DNS Address: 0.0.0.0 (0.0.0.0)

                 Secondary DNS Server IP Address: 0.0.0.0

                     Type: Secondary DNS Server IP Address (131)

                     Length: 6

                     Secondary DNS Address: 0.0.0.0 (0.0.0.0)

     Protocol or Container ID: DNS Server IPv4 Address Request (0x000d)

         Length: 0x00 (0)

     Protocol or Container ID: IP address allocation via NAS signalling (0x000a)

         Length: 0x00 (0)

     Protocol or Container ID: IPv4 Link MTU Request (0x0010)

         Length: 0x00 (0)

Protocol Configuration Options - in Activate Default EPS Bearer Request

NAS EPS session management messages: Activate default EPS bearer context request (0xc1)

EPS quality of service

    Length: 1

    Quality of Service Class Identifier (QCI): QCI 9 (9)

Access Point Name

    Length: 12

    APN: nxtgenphone

PDN address

    Length: 5

    0000 0... = Spare bit(s): 0x00

    PDN type: IPv4 (1)

    PDN IPv4: 192.168.1.1 (192.168.1.1)

Protocol Configuration Options

    Element ID: 0x27

    Length: 27

    [Link direction: Network to MS (1)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

        Length: 0x10 (16)

        PPP IP Control Protocol

            Code: Configuration Nak (3)

            Identifier: 0 (0x00)

            Length: 16

            Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

                Primary DNS Server IP Address: 192.168.1.2

                    Type: Primary DNS Server IP Address (129)

                    Length: 6

                    Primary DNS Address: 192.168.1.2 (192.168.1.2)

                Secondary DNS Server IP Address: 192.168.1.2

                    Type: Secondary DNS Server IP Address (131)

                    Length: 6

                    Secondary DNS Address: 192.168.1.2 (192.168.1.2)

    Protocol or Container ID: DNS Server IPv4 Address (0x000d)

        Length: 0x04 (4)

        IPv4: 192.168.1.2

< Example 4 >

Protocol Configuration Options - in PDN Connectivity Request

NAS EPS session management messages: PDN connectivity request (0xd0)

0011 .... = PDN type: IPv4v6 (3)

.... 0001 = Request type: initial request (1)

Access Point Name

    Element ID: 0x28

    Length: 4

    APN: ims

Protocol Configuration Options

    Element ID: 0x27

    Length: 38

    [Link direction: MS to network (0)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: Internet Protocol Control Protocol (0x8021)

        Length: 0x10 (16)

        PPP IP Control Protocol

            Code: Configuration Request (1)

            Identifier: 0 (0x00)

            Length: 16

            Options: (12 bytes), Primary DNS Server IP Address, Secondary DNS Server IP Address

                Primary DNS Server IP Address: 0.0.0.0

                    Type: Primary DNS Server IP Address (129)

                    Length: 6

                    Primary DNS Address: 0.0.0.0 (0.0.0.0)

                Secondary DNS Server IP Address: 0.0.0.0

                    Type: Secondary DNS Server IP Address (131)

                    Length: 6

                    Secondary DNS Address: 0.0.0.0 (0.0.0.0)

    Protocol or Container ID: DNS Server IPv4 Address Request (0x000d)

        Length: 0x00 (0)

    Protocol or Container ID: DNS Server IPv6 Address Request (0x0003)

        Length: 0x00 (0)

    Protocol or Container ID: P-CSCF IPv6 Address Request (0x0001)

        Length: 0x00 (0)

    Protocol or Container ID: P-CSCF IPv4 Address Request (0x000c)

        Length: 0x00 (0)

    Protocol or Container ID: IP address allocation via NAS signalling (0x000a)

        Length: 0x00 (0)

    Protocol or Container ID: IPv4 Link MTU Request (0x0010)

        Length: 0x00 (0)

Protocol Configuration Options - in Activate Default EPS Bearer Request

NAS EPS session management messages: Activate default EPS bearer context request (0xc1)

EPS quality of service

    Length: 1

    Quality of Service Class Identifier (QCI): QCI 5 (5)

Access Point Name

    Length: 4

    APN: ims

PDN address

    Length: 9

    0000 0... = Spare bit(s): 0x00

    PDN type: IPv6 (2)

    PDN IPv6 if id: 0000000000000011

ESM cause

    Element ID: 0x58

    Cause: PDN type IPv6 only allowed (51)

Protocol Configuration Options

    Element ID: 0x27

    Length: 39

    [Link direction: Network to MS (1)]

    1... .... = Extension: True

    Configuration Protocol: PPP for use with IP PDP type or IP PDN type (0)

    Protocol or Container ID: DNS Server IPv6 Address (0x0003)

        Length: 0x10 (16)

        IPv6: 2001:0:0:1::2

    Protocol or Container ID: P-CSCF IPv6 Address (0x0001)

        Length: 0x10 (16)

        IPv6: 2001:0:0:1::2