draft-ietf-v6ops-ipv6-roaming-analysis-04.txt   draft-ietf-v6ops-ipv6-roaming-analysis-05.txt 
Network Working Group G. Chen Network Working Group G. Chen
Internet-Draft H. Deng Internet-Draft H. Deng
Intended status: Informational China Mobile Intended status: Informational China Mobile
Expires: February 22, 2015 D. Michaud Expires: March 5, 2015 D. Michaud
Rogers Communications Rogers Communications
J. Korhonen J. Korhonen
Broadcom Broadcom
M. Boucadair M. Boucadair
France Telecom France Telecom
A. Vizdal A. Vizdal
Deutsche Telekom AG Deutsche Telekom AG
August 21, 2014 September 1, 2014
IPv6 Roaming Behavior Analysis IPv6 Roaming Behavior Analysis
draft-ietf-v6ops-ipv6-roaming-analysis-04 draft-ietf-v6ops-ipv6-roaming-analysis-05
Abstract Abstract
This document identifies a set of failure cases that may be This document identifies a set of failure cases that may be
encountered by IPv6-enabled mobile customers in roaming scenarios. encountered by IPv6-enabled mobile customers in roaming scenarios.
The analysis reveals that the failure causes include improper The analysis reveals that the failure causes include improper
configurations, incomplete functionality support in equipment, and configurations, incomplete functionality support in equipment, and
inconsistent IPv6 deployment strategies between the home and the inconsistent IPv6 deployment strategies between the home and the
visited networks. visited networks.
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 22, 2015. This Internet-Draft will expire on March 5, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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4.1. Case 1: Splitting Dual-stack Bearer 4.1. Case 1: Splitting Dual-stack Bearer
Dual-stack capability is provided using separate PDP/PDN activation Dual-stack capability is provided using separate PDP/PDN activation
in the visited network that doesn't support PDP/PDN type IPv4v6. in the visited network that doesn't support PDP/PDN type IPv4v6.
That means only separate parallel single-stack IPv4 and IPv6 PDP/PDN That means only separate parallel single-stack IPv4 and IPv6 PDP/PDN
connections are allowed to be initiated to separately allocate an connections are allowed to be initiated to separately allocate an
IPv4 address and an IPv6 prefix. The SGSN does not support the Dual IPv4 address and an IPv6 prefix. The SGSN does not support the Dual
Address Bearer Flag (DAF) or does not set DAF because the operator Address Bearer Flag (DAF) or does not set DAF because the operator
uses single addressing per bearer to support interworking with nodes uses single addressing per bearer to support interworking with nodes
of earlier releases. Regardless of home routed or local breakout of earlier releases. Regardless of home routed or local breakout
mode, visited SGSN will change PDN/PDP type to a single address PDP/ mode, GGSN/PGW will change PDN/PDP type to a single address PDP/PDN
PDN type and return the Session Management (SM) Cause #52 "Single type and return the Session Management (SM) Cause #52 "Single address
address bearers only allowed" or SM Cause #28 "Unknown PDP address or bearers only allowed" or SM Cause #28 "Unknown PDP address or PDP
PDP type" as per [TS24.008] and [TS24.301]. to the UE. In this case, type" as per [TS24.008] and [TS24.301] to the UE. In this case, the
the UE may make another PDP/PDN request with a single address PDP UE may make another PDP/PDN request with a single address PDP type
type (IPv4 or IPv6) other than the one already activated. (IPv4 or IPv6) other than the one already activated.
This approach suffers from the followings drawbacks: This approach suffers from the followings drawbacks:
o The parallel PDP/PDN activation would likely double PDP/PDN bearer o The parallel PDP/PDN activation would likely double PDP/PDN bearer
resource on the network side and Radio Access Bearer (RAB) resource on the network side and Radio Access Bearer (RAB)
resource on the RAN side. It also impacts the capacity of the resource on the RAN side. It also impacts the capacity of the
GGSN/PGW, since only a certain amount of PDP/PDN activation is GGSN/PGW, since only a certain amount of PDP/PDN activation is
only allowed on those nodes. only allowed on those nodes.
o Some networks may only allow one PDP/PDN be alive for each o Some networks may only allow one PDP/PDN be alive for each
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(QoS) policies. The subscriber may have unstable experiences due (QoS) policies. The subscriber may have unstable experiences due
to different behaviors on each IP version connection. to different behaviors on each IP version connection.
o Mobile devices may have a limitation on allowed simultaneous PDP/ o Mobile devices may have a limitation on allowed simultaneous PDP/
PDN contexts. Excessive PDP/PDN activation may result in service PDN contexts. Excessive PDP/PDN activation may result in service
disruption. disruption.
In order to avoid the issue, the roaming agreement in the home routed In order to avoid the issue, the roaming agreement in the home routed
mode should make sure the visited SGSN support and set the DAF. mode should make sure the visited SGSN support and set the DAF.
Since the PDP/PDN type IPv4v6 is supported in the GGSN/PGW of home Since the PDP/PDN type IPv4v6 is supported in the GGSN/PGW of home
network, the visited SGSN/MME should create dual-stack bearer as UE network, it's expected that the visited SGSN/MME could create dual-
requested. stack bearer as UE requested.
In the local breakout mode, the visited GGSN may only allow single IP In the local breakout mode, the visited SGSN may only allow single IP
version addressing. In this case, DAF on visited SGSN/MME has to be version addressing. In this case, DAF on visited SGSN/MME has to be
unset. One approach is to set a dedicated Access Point Name (APN) unset. One approach is to set a dedicated Access Point Name (APN)
[TS23.003] profile to only request PDP/PDN type IPv4 in the roaming [TS23.003] profile to only request PDP/PDN type IPv4 in the roaming
network. Some operators may also consider not adopting the local network. Some operators may also consider not adopting the local
breakout mode to avoid the risks. breakout mode to avoid the risks.
4.2. Case 2: IPv6 PDP/PDN Unsupported 4.2. Case 2: IPv6 PDP/PDN Unsupported
PDP/PDN type IPv6 has good compatibility to visited networks during PDP/PDN type IPv6 has good compatibility to visited networks during
the network attachment. In order to support the IPv6-only visitors, the network attachment. In order to support the IPv6-only visitors,
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