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TS 29.139
3GPP System - Fixed Broadband Access Network Interworking –
Home (e)Node B - Security Gateway Interface

Use "3GPP‑Page" to get the Word version, and "ETSI‑search" to get the PDF version
V16.0.0 (PDF)  2020/06  14 p.
V15.0.0  2018/06  13 p.
V14.0.0  2017/03  14 p.
V13.1.0  2016/03  14 p.
V12.1.0  2016/03  14 p.
V11.2.0  2016/03  14 p.
Rapporteur:
Mr. Yang, YongEricsson LM

Content for  TS 29.139  Word version:  16.0.0

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1  ScopeWord‑p. 5
The present document specifies the H(e)NB - SeGW interface. The interface is used for the interworking between a 3GPP system and a Fixed Broadband Access network defined by Broadband Forum. The interworking procedure provides the IP connectivity to a 3GPP UE using a H(e)NB connected to a Fixed Broadband Access network as specified in TS 23.139.
The specification covers the QoS aspects and Tunnel management procedures.

2  References

The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
  • References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
  • For a specific reference, subsequent revisions do not apply.
  • For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
TS 23.139: "3GPP System-Fixed Broadband Access Network Interworking; Stage 2".
[3]
TS 24.139: "3GPP System-Fixed Broadband Access Network Interworking; Stage 3".
[4]
RFC 2474  (December 1998): "Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers".
[5]
RFC 5996:  " Internet Key Exchange Protocol Version 2 (IKEv2)".
[6]
RFC 3948:  "UDP Encapsulation of IPsec ESP Packets".
[7]
TS 33.320: "Security of Home Node B (HNB) / Home evolved Node B (HeNB)".
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3  Definitions and abbreviations

3.1  Definitions

For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
H(e)NB Reflective QoS function:
H(e)NB Reflective QoS function is a H(e)NB function in order to support QoS for uplink traffic over a Fixed Broadband Access network as specified in TS 23.139.
H(e)NB local IP address Info:
H(e)NB local IP address Info is defined as either the public IPv4 address or IPv6 address assigned to the H(e)NB by the Fixed Broadband Access Network domain, or the public IPv4 address and the UDP port number used by the NATed RG that is used for this H(e)NB. The public IPv4 address used by the NATed RG is assigned by the Fixed Broadband Access Network domain.
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3.2  AbbreviationsWord‑p. 6
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
DSCP
Differentiated Services Code Point
H(e)NB
Home (e)NodeB
NAT
Network Address Translation
NAT-T
NAT Traversal
SeGW
Security Gateway

4  General

4.1  Protocol Stack

4.1.1  Control Plane for H(e)NB - SeGW

(not reproduced yet)
Figure 4.1.1-1: Control Plane for H(e)NB - SeGW Interface over IPv4 transport network
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Legend:
  • IKEv2 Protocol: This protocol is used to between H(e)NB and SeGW. The IKEv2 protocol is defined in RFC 5996.
(not reproduced yet)
Figure 4.1.1-2: Control Plane for H(e)NB - SeGW Interface over IPv6 transport network
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Legend:
  • IKEv2 Protocol: This protocol is used to between H(e)NB and SeGW. The IKEv2 protocol is defined in RFC 5996.

4.1.2  User Plane for H(e)NB - SeGWWord‑p. 7
(not reproduced yet)
Figure 4.1.2-1: User Plane for H(e)NB - SeGW Interface over IPv4 transport network
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Legend:
  • UDP: UDP encapsulation is used if NAT is detected between the H(e)NB and the SeGW.
  • (not reproduced yet)
    Figure 4.1.2-2: User Plane for H(e)NB - SeGW Interface over IPv6 transport network
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    5  Supporting QoSWord‑p. 8

    5.1  General

    At interworking with a Fixed Broadband Access network, QoS is provided by DSCP marking as specified in RFC 2474.

    5.2  H(e)NB procedures

    5.2.1  General

    The H(e)NB shall support DSCP marking on the IPsec header when forwarding the UE uplink traffic.
    Based on H(e)NB configuration either the QCI mapping or the Reflective QoS may be used.

    5.2.2  QCI mapping

    The QCI mapping table contains a one-to-one mapping from QCI value to DSCP marking value. The QCI mapping table is configured in the H(e)NB by the operator.
    When forwarding an uplink IP packet, the H(e)NB shall perform a lookup in the QCI mapping table based on the QCI value of the EPS bearer/PDP context before the IPsec tunnel encapsulation. The H(e)NB shall set the DSCP marking value of the IPsec header according to the matched QCI mapping table entry.

    5.2.3  Reflective QoS

    To support the H(e)NB Reflective QoS function for uplink traffic, the H(e)NB shall create and maintain the uplink DSCP marking rules for each active PDN connection as specified for UE Reflective QoS function in TS 24.139.
    When forwarding an uplink IP packet, the H(e)NB shall perform a lookup in the DSCP marking table based on the n-tuple of the IP header before the IPsec tunnel encapsulation. If a matching entry is found, the H(e)NB shall set the DSCP marking value of the IPsec header according to the matched DSCP marking rule. If no matching entry is found, the H(e)NB shall copy the DSCP field of the outer IP header into the IPsec header before forwarding to the SeGW.
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    5.3  SeGW procedures

    When receiving a downlink data packet, the SeGW shall copy the DSCP marking value from the outer IP header into the IPsec header before forwarding to the H(e)NB using the IPsec tunnel, as specified in TR 23.139.

    6  Tunnel Management

    6.1  General

    The tunnel is an IPsec tunnel established via an IKEv2 protocol exchange RFC 5996 between the H(e)NB and the SeGW which is through the Fixed Broadband Access Network.
    In an IPv4 Fixed Broadband Access Network, NAT can be deployed between the H(e)NB and the SeGW, e.g. in a Residence Gateway. A H(e)NB behind the NAT shall invoke the NAT traversal procedure for IKEv2. The IPsec tunnel is encapsulated over UDP in the Tunnel-Mode as specified in RFC 5996.
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    6.2  H(e)NB proceduresWord‑p. 9

    6.2.1  Tunnel establishment

    6.2.1.1  IP address allocation

    The SeGW shall provide the IP address to the H(e)NB for the communication with the EPC network.
    For dynamic IP address allocation, the H(e)NB shall include the requested IP address type (IPv4 address or IPv6 address) that needs to be configured in an IKEv2 CFG_REQUEST Configuration Payload in the IKE_AUTH request message as defined in RFC 5996 after reception of the IKE_SA_INIT response from the SeGW.

    6.2.1.2  NAT Traversal

    NAT can be deployed in an IPv4 Fixed Broadband Access Network. IKEv2 NAT Traversal specified in clause 2.23 of RFC 5996 shall be supported by H(e)NB.
    If NAT is detected between the H(e)NB and SeGW, the following procedures shall be performed:
    • UDP-Encapsulated ESP as defined in RFC 5996;
    • sending the NAT-keepalive packet to keep NAT mapping alive if no other packet to the SeGW has been sent in M seconds as defined in the RFC 3948;
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    6.2.1.3  H(e)NB NATed Tunnel-IP address discovery

    If NAT is detected between the H(e)NB and SeGW, the H(e)NB shall request the SeGW to return the H(e)NB local IP address information by including the EXTERNAL_SOURCE_IP4_NAT_INFO attribute as defined in subclause 7.1.1.1 in the CFG_REQUEST Configuration Payload within the IKE_AUTH request message. The length field of the attribute shall be set to zero. The NATed IPv4 Address field and UDP Port number field shall be absent.
    If the H(e)NB subsequently receives the EXTERNAL_SOURCE_IP4_NAT_INFO attribute in the CFG_REPLY configuration payload from the SeGW, the H(e)NB shall report the IP address received in EXTERNAL_SOURCE_IP4_NAT_INFO attribute as the H(e)NB local IP address to the MME/SGSN.
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    6.2.2  Tunnel modification

    NAT mappings can change when the UDP port number is reassigned by the NAT, and/or H(e)NB local IP address is reallocated due to NAT restart.
    Upon NAT remapping, the SeGW initiates the tunnel disconnection procedure as specified in subclause 6.3.3. Then the H(e)NB shall re-initiate the tunnel establishment procedure as specified in sub-clause 6.2.1.

    6.2.3  Tunnel disconnection

    The H(e)NB shall use the procedures defined in RFC 5996 to disconnect an IPsec tunnel to the SeGW.

    6.3  SeGW procedures

    6.3.1  Tunnel establishment

    6.3.1.1  IP address allocation

    For dynamic IP address allocation, upon receipt of an IKE_AUTH request message from the H(e)NB requesting the IP address, the SeGW shall include the remote IP address information in the IKEv2 Configuration Payload (CFG_REPLY) of the final IKE_AUTH response message to the H(e)NB. The SeGW shall assign either an IPv4 or an IPv6 address to the H(e)NB via a single CFG_REPLY Configuration Payload.

    6.3.1.2  NAT TraversalWord‑p. 10
    NAT can be deployed in an IPv4 Fixed Broadband Access Network. IKEv2 NAT Traversal specified in section 2.23 of RFC 5996 shall be supported by SeGW.
    If NAT is detected between the H(e)NB and SeGW, the SeGW shall use UDP-Encapsulated ESP as defined in RFC 5996.

    6.3.1.3  H(e)NB NATed Tunnel-IP address discovery

    If the SeGW receives the EXTERNAL_SOURCE_IP4_NAT_INFO attribute as defined in subclause 7.1.1.1 in the CFG_REQUEST configuration payload within IKE_AUTH request message, the SeGW shall provide the H(e)NB local IP address information (i.e. NATed IPv4 address and UDP port number) to the H(e)NB by including the EXTERNAL_SOURCE_IP4_NAT_INFO attribute in the CFG_REPLY configuration payload within the IKE_AUTH response message.

    6.3.2  Tunnel modification

    NAT mappings can change when the UDP port number is reassigned by the NAT, and/or H(e)NB local IP address is reallocated due to NAT restart.
    If NAT remapping is detected by the SeGW, the SeGW shall initiate the tunnel disconnection procedure (see subclause 6.3.3).
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    6.3.3  Tunnel disconnection

    The SeGW shall use the procedures defined in RFC 5996 to disconnect an IPsec tunnel to the H(e)NB.

    7  PDUs and parameters specific to the present document

    7.1  IETF RFC coding information defined within present document

    7.1.1  IKEv2 Configuration Payloads attributes

    7.1.1.1  EXTERNAL_SOURCE_IP4_NAT_INFO attribute

    The format of the EXTERNAL_SOURCE_IP4_NAT_INFO attribute follows the definition of Configuration Attributes as specified in RFC 5996 clause 3.15.1. The format is shown in Figure 7.1.1.1-1 as below. The length of the EXTERNAL_SOURCE_IP4_NAT_INFO attribute is 0 or 6 bytes.
    (not reproduced yet)
    Figure 7.1.1.1-1: EXTERNAL_SOURCE_IP4_NAT_INFO attribute
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    The R bit in the first octet is as defined in RFC 5996.
    The Attribute Type indicating EXTERNAL_SOURCE_IP4_NAT_INFO is of the value 23.

    $  Change HistoryWord‑p. 12

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