Internet DRAFT - draft-camarillo-dmm-srv6-mobile-pocs
draft-camarillo-dmm-srv6-mobile-pocs
DMM Working Group P. Camarillo
Internet-Draft C. Filsfils
Intended status: Informational Cisco Systems, Inc.
Expires: October 26, 2019 L. Bertz
Sprint
A. Akhavain
Huawei Canada Research Centre
S. Matsushima
SoftBank
D. Voyer
Bell Canada
April 24, 2019
Segment Routing IPv6 for mobile user-plane PoCs
draft-camarillo-dmm-srv6-mobile-pocs-02
Abstract
This document describes the ongoing proof of concepts of
[I-D.ietf-dmm-srv6-mobile-uplane] and their progress.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. M-CORD C3PO . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. PoC phases . . . . . . . . . . . . . . . . . . . . . . . 3
3.2. Activity report . . . . . . . . . . . . . . . . . . . . . 3
3.2.1. Phase 1 . . . . . . . . . . . . . . . . . . . . . . . 3
4. Open Air Interface . . . . . . . . . . . . . . . . . . . . . 4
4.1. PoC phases . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1. Phase 1: Mobile Core Migration from IPv4-GTP to SRv6 5
4.2. Activity report . . . . . . . . . . . . . . . . . . . . . 6
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
6. Informative References . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The [I-D.ietf-dmm-srv6-mobile-uplane] proposes SRv6 as userplane
protocol for mobile networks. As part of this work we have decided
to create a series of PoCs with the objective to prove the viability
and feasibility of such proposal.
For this reason we have two ongoing PoCs using M-CORD C3PO and OAI,
that are progressing towards a full implementation of the mechanisms
described in such I-D.
This I-D contains a formal definition of the PoCs and will summarize
it's findings. Anyone interested in participating in the ongoing
PoCs or propose new ones is welcome to join us.
2. Terminology
This document adopts the terminology of
[I-D.ietf-dmm-srv6-mobile-uplane].
This document uses the terms N3, N6 and N9 interfaces, as well as UPF
and gNB as refered to in [TS.23501].
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3. M-CORD C3PO
M-CORD <https://www.opennetworking.org/m-cord/> is an open-source
project from ONF focused on building a cloud-native virtualized and
dissagregated RAN and EPC.
As part of the M-CORD project, the C3PO component is part of the NGIC
(Next Generation Infrastructure Core)
<https://gerrit.opencord.org/#/admin/projects/ngic>.
The scope of this PoC is to extend the C3PO component to support
natively SRv6 on the N6 and N9 interfaces and have SRv6-supported
UPFs.
3.1. PoC phases
This PoC is divided in several phases:
1. SRv6 in transport network with no impact to EPC
2. SRv6 native in N6 interface (GiLAN) with SRv6 transport network
3. SRv6 native in N6 and N9 interfaces with N3 interworking
mechanisms
3.2. Activity report
Phase 1 has been completed. Ongoing development of phase 2.
3.2.1. Phase 1
We used FD.io VPP <https://fd.io/technology/> to simulate an SRv6
transport network with three SRv6 routers in the N9 interface
simulating a transport network.
As part of this transport network, we run two simulations:
In the first simulation we steered the IPv4/GTP traffic into an SR
policy that encapsulated the packet with an SRv6 header containing
two SIDs.
In the second simulation we steered the IPv4/GTP traffic into an SR
policy that removed the IPv4/GTP headers and placed the GTP header
information (i.e. TEID) into an SRv6 SID. The last SID of the SR
policy corresponds to an End.M.GTP4.E function, that decapsulates
SRv6 traffic restoring the IPv4/GTP header. The objective of the
second simulation is to show the IPv4/GTP interworking mechanism via
an uplink classifier behaving as SR-GW, as defined in Section 6.4 of
[I-D.ietf-dmm-srv6-mobile-uplane] .
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After Phase 1, we concluded that SRv6 as mobility transport network
works fine, with an expected MTU overhead due to the original PDU
encapsulation. The IPv4/GTP interworking mechanism in the scope of
phase 1 is also fully functional. This mechanism will be further
tested as the POC progresses and a native SRv6-based UPF is
developed.
4. Open Air Interface
Open Air Interface (OAI) is an open-source software
<http://www.openairinterface.org/?page_id=2762> that implements the
3GPP stack. OAI is composed of two major projects: OAI-RAN and OAI-
CN.
o OAI-RAN implements the 4G LTE and 5G Radio Access Network. Both
the gNB as well as the UE are implemented.
o OAI-Core Network implements the 4G LTE Evolved Packet Core (EPC)
and 5G Core Network.
The scope of this PoC is to extend the OAI-RAN and OAI-CN components
to support natively SRv6 on the N3 and N9 interfaces, and have
SRv6-supported gNBs and UPFs.
4.1. PoC phases
The primary goal of this POC is to show SRv6 as a data plane
replacement for GTP on both N3 and N9 interfaces. The POC also aims
to demonstrate a smooth migration path during deployment and
transition period from IPv4-GTP and IPv6-GTP to an end to end SRv6
data plane.
The PoC functions within the existing OAI model. OAI currently
doesn't provide support for S5/S8 interface. The implementation
instead provides an integrated SGW and PGW S/PGW module and therefore
there is no GTP tunnel between these two entities. This limitation
has an impact on the POC strategy and its implementation phases.
This PoC is divided into several phases:
1.- N3 via SRv6 GW VNFs and no impact on 3GPP control plane.
1.1.- Mobile Core Migration from IPv4-GTP to SRv6
1.2.- Mixed IPv4-GTP/IPv6-GTP Mobile Core Over SRv6
2.- N3 via SRv6 eNB and S/PGW integrated modules and no impact on
3GPP control plane.
2.1.- Mobile Core Migration from IPv4-GTP to SRv6
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2.2.- Mixed IPv4-GTP/IPv6-GTP Mobile Core Over SRv6
3.- N3 via SRv6 support of ID-LOC architecture
Important notes:
- The above phases and solution strategy can easily be extended to
the N9 interface. However, although the N9 interface is well
within the scope of this PoC, the effort required to changes the
OAI code base to support S5/S8 and separate SGW and PGW modules
will push the project well beyond the timeline of this PoC and as
such are not currently part of the PoC.
- Support for service programming, TE, QoS, entropy, and other
enhanced features are also within the scope of this PoC, but will
also fall beyond the time line of this project and are not
currently considered in this PoC.
- The above items can be pulled back into the project based on demand
and assistance from others.
4.1.1. Phase 1: Mobile Core Migration from IPv4-GTP to SRv6
Phase one of this POC focuses on demonstrating a smooth migration
path from the existing mobile core networks with IPv4 GTP based user
plane to SRv6 user plane with absolutely no impact on 3GPP control
plane. The idea is to employ SRv6 gateways between mobile core
equipment such as eNB, SGW, and PGW, intercept GTP traffic, and carry
UE's payload through SRv6 newtwork by encoding GTP information into
the SIDs.
In this POC as it was mentioned earlier we use OAI open source
software. OAI implements gNB as an stand alone entitiy, but bundles
MME, SGW and PGW into a single package. We employ three Linux PCs in
oursetup. Two of these machines run the gNB and one of the SRv6 GWs.
The thrid machines employs virtualisation and instantiates two
virtual machines. The second SRv6 gateway runs in one of the virtual
machine while the other virtual machines executes the code for the
combinged MME, SGW, PGW. The code in SRv6 gateways is based on VPP
implementation in Linux Foundation. We modified this code to
intercept GTP packets, extract GTP information, and encode GTP
information into the SIDs. Given that today's mobile core don't deal
with multiple UPFs, the resulting SRv6 haeader doesn't require any
SRH to carry GTP information across the network. Therefore, in this
phase, the resulting SRv6 packets are simply IPv6 packets with their
DA set to SIDs. The following diagratm shows the POC configuration.
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+--------------------------+
| +========+|
+--+ \|/ | | +---+ ||
|UE| | | | |HSS| ||
+--+ | | | +-+-+ ||
+--+ | | | ||
| | | +-+-+ ||
+-+ | | |MME| ||
| | | +---+ ||
| GTP<->SID | GTP<->SID | ||
+---+---+ +-----+ +--------+ | +========+ |+------+||
| USRP | | | | | | | | || |||
|(Ettus +---+ gNB +-GTP--+ SRGW-1 +--SRv6-|-+ SRGW-2 +-GTP-|+ SPGW |||
| B210) | ^ | | | | | | | || |||
+-------+ | +-----+ +--------+ | +========+ |+--+---+||
| | VM-1 | | ||
USB | | | ||
| +========+|
| VM-2 | |
| | |
+--------------------|-----+
|
|
DN
POC Configuration
In this implementation, the SRGW at one end extracts relavant GTP
informaton(SA, DA, TEID) from GTP and encodes them into the lower 96
bits of SID. The SID is then copied into the DA of IPv6 header and
the packet is forwarded toward the SRGW at the far end. Receiving
the SRv6 packet, the far end SRGW recognises the SID as local and
executes a set of functions that extracts GTP information from the
SID, forms the GTP packet by adding relevant UDP and GTP headers and
forward this reconstructed GTP packet to its associated mobile core
node.
4.2. Activity report
Development started. Phase 1 has been completed.
5. Contributors
Chenchen Liu
Huawei Technolgies Co., Ltd.
Shenzhen, China
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Email: liuchenchen1@huawei.com
Arun Rajagopal
Sprint
United States of America
Email: Arun.Rajagopal@sprint.com
Mark Bales
Sprint
United States of America
Email: Mark.Bales@sprint.com
Robert Butler
Sprint
United States of America
Email: Robert.Butler@sprint.com
6. Informative References
[I-D.filsfils-spring-srv6-network-programming]
Filsfils, C., Camarillo, P., Leddy, J.,
daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
Network Programming", draft-filsfils-spring-srv6-network-
programming-07 (work in progress), February 2019.
[I-D.ietf-dmm-srv6-mobile-uplane]
Matsushima, S., Filsfils, C., Kohno, M., Camarillo, P.,
daniel.voyer@bell.ca, d., and C. Perkins, "Segment Routing
IPv6 for Mobile User Plane", draft-ietf-dmm-srv6-mobile-
uplane-04 (work in progress), March 2019.
[TS.23501]
3GPP, "System Architecture for the 5G System", 3GPP TS
23.501 15.0.0, November 2017.
Authors' Addresses
Pablo Camarillo Garvia
Cisco Systems, Inc.
Spain
Email: pcamaril@cisco.com
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Clarence Filsfils
Cisco Systems, Inc.
Belgium
Email: cf@cisco.com
Lyle T Bertz
Sprint
United States of America
Email: Lyle.T.Bertz@sprint.com
Arashmid Akhavain
Huawei Canada Research Centre
Canada
Email: arashmid.akhavain@huawei.com
Satoru Matsushima
SoftBank
Tokyo
Japan
Email: satoru.matsushima@g.softbank.co.jp
Daniel Voyer
Bell Canada
Canada
Email: daniel.voyer@bell.ca
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