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IPv6 in 3GPP Evolved Packet System

draft-korhonen-v6ops-3gpp-eps

Jouni Korhonen, Jonne Soininen, Basavaraj Patil,Teemu Savolainen, Gabor Bajko, Kaisu Iisakkila

V6OPS IETF #77

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Overview

Describes 3GPP Release-8 Evolved PacketSystem and Evolved Packet Core architectures.

Explains how IPv6 is supported in the

architecture and the different types ofbearers.

Explains some of the basic concepts and

terminology of 3GPP IP access. Mostly about what is already there not

about all possible enhancements..

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Some Common Terminology..

EPC = Evolved Packet Core

RAN = Radio Access Network

EPS = Evolved Packet System (EPC + RAN)

eNodeB = evolved NodeB i.e. base station in EPS

3GPP Access = radio system developed by 3GPP

Non-3GPP Access = radio system not developed by 3GPP UE = User Equipment i.e., a mobile host, wireless device

APN = Access Point Name

PDN = Packet Data Network i.e. an IP network

SGSN = Serving GPRS Support Node

GGSN = Gateway GPRS Support Node

SGW = Service Gateway PDN-GW = Packet Data Network Gateway

MME = Mobility Management Entity

Release-x = named version of the GPRS/EPS architecture (eg. Rel 4, Rel 5 etc)

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Basic Evolved Packet System

Architecture

Architecture supports EUTRAN and legacy 2G/3Gaccesses as well

PtP link is established between the UE and the P-GW

User-plane traffic always tunneled over the transportnetwork.

User-plane addressing independent of transportnetwork addressing and IP versions.

PDN-

GW

SGW

MME

eNodeBUE

S1-MME S11

S1-U S5/S8LTE-Uu

Dual-Stack EPS Bearer

PDN / IP

ServicesSGi

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EPS Bearer Model

A logical concept of a bearer has been definedas an aggregate of one or more IP flowsrelated to one or more services.

The EPS bearer is between the UE and thePDN-GW, and used to transport IP (v4 and/orv6) packets

The UE performs the binding of the UL IPflows and the PDN-GW performs the bindingof the DL IP flows

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Access Point Name concept

UEs and network use APNs to identify a network (e.g.internet, corporate intra-network, etc) and to someextent the associated services in that network.Example internet.example.com

APNs are piggybacked on the administration of theDNS namespace. Release-8 uses extensively S-NAPTR,where are pre-Release-8 was just A/AAAA.

During the connection (bearer) setup, APNs are used(by SGSN/MME) to discover the gateway (GGSN/PDN-GW) that provides the IP connectivity to the networkidentifier by the APN, supported protocols, topologicallocation collocation propertied of gateways.

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Access Point Name concept contd

UE would just request an APN e.g. forinternet or request nothing..

MME either figures out the defaultAPN for the UE/subscriber.. or

..MME would substitute a full domainname of the APN received from the UE

MME would then: Query a NAPTR for the domain

Select the NAPTR which matches therequired protocols and such..

Query A/AAAA for both SGW and PDN-GW

Push the selected PDN-GW address toselected PGW

PDN-

GWSGW

MME

eNodeBUE

S11

S5/S8PDN / IP

ServicesSGi

DNS

$ORIGIN epc.mnc123.mcc345.3gppnetwork.org.

...

internet.apn

IN NAPTR 10 1 "a" "x-3gpp-pgw:x-s5-gtp" "" topoff.b1.gw1.nodes

IN NAPTR 20 2 "a" "x-3gpp-pgw:x-s5-pmip "" topoff.b1.gw2.nodes

...

topoff.b1.gw1.nodes IN A 192.0.2.113

IN A 192.0.2.114IN AAAA 2001:db8:0:c:0:0:0:0

IN AAAA 2001:db8:0:d:0:0:0:0

topoff.b2.gw2.nodes IN A 192.0.2.143

IN A 192.0.2.144

IN AAAA 2001:db8:0:2a:0:0:0:0

...

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EPS Bearer Types

IPv4 only bearer. The bearer is configured with one IPv4 address.

The link is IPv4 only.

IPv6 only bearer. The bearer is configured with one /64 prefix.

The link is IPv6 only.

IPv4v6 bearer. The bearer is configured with both IPv4 address and one /64

prefix.

New bearer type since Release-8.

The link is dual-stack.

V4v6 bearer type is the default in Rel-8 and beyond

Rel 9 has also introduced the DS PDP context type for UTRANand EDGE

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PDN Connection Establishment

UE eNodeB MME SGW PDN-GE HSS/AAA

Authentication and Authorization

RB Setup

1)

1)

2)

3)

3)

4)

5)

4)

6)

7)

8)

9)

10)

11)

12)

13)

UL Data

DL Data

1. Attach request

2. Auth/AuthZ phase

3. Create Session Request

4. Create Session Response

5. Initial context setup

request/Attach accept6. Radio bearer reconfig

7. Initial context setupresponse

8. Direct transfer

9. Attach complete

10. UE starts sending UL data11. Modify bearer request

12. Modify response

13. DL data transmission starts

Address/

prefix

allocation

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Dual-Stack Approach for IP Access

Networks prior to Release-8

Dual-stack connectivity possible by opening twoparallel PDP Contexts of types IPv4 and IPv6.

Shows up as two separate interfaces to the IPstack.

Networks from Release-8 onwards.

A single IPv4v6 PDN Connection in addition tohaving separate v4 and v6 PDN connections.

Shows up as one interface with both IPv4 and IPv6addresses to the IP stack (with v4v6 type).

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Dual-stack approach

NodeB/BTS

eNode

B

S-GW

MME

P-GW

DS-PDN

Type v4v6 PDN

connection

NodeB/BTS

BS

SGSN

GGSN

IPv4-PDN

IPv4-APNIPv4-PDP Context

GGSN

IPv6-APNIPv6-PDN

In Rel 8 and beyond networks

In Pre Rel 8 networks

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Next Steps..

Request adoption of this I-D as a V6OPS

document describing relevant parts of the

3GPP Evolved Packet System.

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