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2 DMM Working Group P. Camarillo
3 Internet-Draft C. Filsfils
4 Intended status: Informational Cisco Systems, Inc.
5 Expires: April 25, 2019 L. Bertz
6 Sprint
7 A. Akhavain
8 Huawei Canada Research Centre
9 S. Matsushima
10 SoftBank
11 D. Voyer
12 Bell Canada
13 October 22, 2018
15 Segment Routing IPv6 for mobile user-plane PoCs
16 draft-camarillo-dmm-srv6-mobile-pocs-01
18 Abstract
20 This document describes the ongoing proof of concepts of
21 [I-D.ietf-dmm-srv6-mobile-uplane] and their progress.
23 Status of This Memo
25 This Internet-Draft is submitted in full conformance with the
26 provisions of BCP 78 and BCP 79.
28 Internet-Drafts are working documents of the Internet Engineering
29 Task Force (IETF). Note that other groups may also distribute
30 working documents as Internet-Drafts. The list of current Internet-
31 Drafts is at https://datatracker.ietf.org/drafts/current/.
33 Internet-Drafts are draft documents valid for a maximum of six months
34 and may be updated, replaced, or obsoleted by other documents at any
35 time. It is inappropriate to use Internet-Drafts as reference
36 material or to cite them other than as "work in progress."
38 This Internet-Draft will expire on April 25, 2019.
40 Copyright Notice
42 Copyright (c) 2018 IETF Trust and the persons identified as the
43 document authors. All rights reserved.
45 This document is subject to BCP 78 and the IETF Trust's Legal
46 Provisions Relating to IETF Documents
47 (https://trustee.ietf.org/license-info) in effect on the date of
48 publication of this document. Please review these documents
49 carefully, as they describe your rights and restrictions with respect
50 to this document. Code Components extracted from this document must
51 include Simplified BSD License text as described in Section 4.e of
52 the Trust Legal Provisions and are provided without warranty as
53 described in the Simplified BSD License.
55 Table of Contents
57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
58 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2
59 3. M-CORD C3PO . . . . . . . . . . . . . . . . . . . . . . . . . 3
60 3.1. PoC phases . . . . . . . . . . . . . . . . . . . . . . . 3
61 3.2. Activity report . . . . . . . . . . . . . . . . . . . . . 3
62 3.2.1. Phase 1 . . . . . . . . . . . . . . . . . . . . . . . 3
63 4. Open Air Interface . . . . . . . . . . . . . . . . . . . . . 4
64 4.1. PoC phases . . . . . . . . . . . . . . . . . . . . . . . 4
65 4.1.1. Phase 1: Mobile Core Migration from IPv4-GTP to SRv6 5
66 4.2. Activity report . . . . . . . . . . . . . . . . . . . . . 6
67 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
68 6. Informative References . . . . . . . . . . . . . . . . . . . 7
69 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
71 1. Introduction
73 The [I-D.ietf-dmm-srv6-mobile-uplane] proposes SRv6 as userplane
74 protocol for mobile networks. As part of this work we have decided
75 to create a series of PoCs with the objective to prove the viability
76 and feasibility of such proposal.
78 For this reason we have two ongoing PoCs using M-CORD C3PO and OAI,
79 that are progressing towards a full implementation of the mechanisms
80 described in such I-D.
82 This I-D contains a formal definition of the PoCs and will summarize
83 it's findings. Anyone interested in participating in the ongoing
84 PoCs or propose new ones is welcome to join us.
86 2. Terminology
88 This document adopts the terminology of
89 [I-D.ietf-dmm-srv6-mobile-uplane].
91 This document uses the terms N3, N6 and N9 interfaces, as well as UPF
92 and gNB as refered to in [TS.23501].
94 3. M-CORD C3PO
96 M-CORD is an open-source
97 project from ONF focused on building a cloud-native virtualized and
98 dissagregated RAN and EPC.
100 As part of the M-CORD project, the C3PO component is part of the NGIC
101 (Next Generation Infrastructure Core)
102 .
104 The scope of this PoC is to extend the C3PO component to support
105 natively SRv6 on the N6 and N9 interfaces and have SRv6-supported
106 UPFs.
108 3.1. PoC phases
110 This PoC is divided in several phases:
112 1. SRv6 in transport network with no impact to EPC
113 2. SRv6 native in N6 interface (GiLAN) with SRv6 transport network
114 3. SRv6 native in N6 and N9 interfaces with N3 interworking
115 mechanisms
117 3.2. Activity report
119 Phase 1 has been completed. Ongoing development of phase 2.
121 3.2.1. Phase 1
123 We used FD.io VPP to simulate an SRv6
124 transport network with three SRv6 routers in the N9 interface
125 simulating a transport network.
127 As part of this transport network, we run two simulations:
129 In the first simulation we steered the IPv4/GTP traffic into an SR
130 policy that encapsulated the packet with an SRv6 header containing
131 two SIDs.
133 In the second simulation we steered the IPv4/GTP traffic into an SR
134 policy that removed the IPv4/GTP headers and placed the GTP header
135 information (i.e. TEID) into an SRv6 SID. The last SID of the SR
136 policy corresponds to an End.M.GTP4.E function, that decapsulates
137 SRv6 traffic restoring the IPv4/GTP header. The objective of the
138 second simulation is to show the IPv4/GTP interworking mechanism via
139 an uplink classifier behaving as SR-GW, as defined in Section 6.4 of
140 [I-D.ietf-dmm-srv6-mobile-uplane] .
142 After Phase 1, we concluded that SRv6 as mobility transport network
143 works fine, with an expected MTU overhead due to the original PDU
144 encapsulation. The IPv4/GTP interworking mechanism in the scope of
145 phase 1 is also fully functional. This mechanism will be further
146 tested as the POC progresses and a native SRv6-based UPF is
147 developed.
149 4. Open Air Interface
151 Open Air Interface (OAI) is an open-source software
152 that implements the
153 3GPP stack. OAI is composed of two major projects: OAI-RAN and OAI-
154 CN.
156 o OAI-RAN implements the 4G LTE and 5G Radio Access Network. Both
157 the gNB as well as the UE are implemented.
158 o OAI-Core Network implements the 4G LTE Evolved Packet Core (EPC)
159 and 5G Core Network.
161 The scope of this PoC is to extend the OAI-RAN and OAI-CN components
162 to support natively SRv6 on the N3 and N9 interfaces, and have
163 SRv6-supported gNBs and UPFs.
165 4.1. PoC phases
167 The primary goal of this POC is to show SRv6 as a data plane
168 replacement for GTP on both N3 and N9 interfaces. The POC also aims
169 to demonstrate a smooth migration path during deployment and
170 transition period from IPv4-GTP and IPv6-GTP to an end to end SRv6
171 data plane.
173 The PoC functions within the existing OAI model. OAI currently
174 doesn't provide support for S5/S8 interface. The implementation
175 instead provides an integrated SGW and PGW S/PGW module and therefore
176 there is no GTP tunnel between these two entities. This limitation
177 has an impact on the POC strategy and its implementation phases.
179 This PoC is divided into several phases:
181 1.- N3 via SRv6 GW VNFs and no impact on 3GPP control plane.
183 1.1.- Mobile Core Migration from IPv4-GTP to SRv6
184 1.2.- Mixed IPv4-GTP/IPv6-GTP Mobile Core Over SRv6
186 2.- N3 via SRv6 eNB and S/PGW integrated modules and no impact on
187 3GPP control plane.
189 2.1.- Mobile Core Migration from IPv4-GTP to SRv6
190 2.2.- Mixed IPv4-GTP/IPv6-GTP Mobile Core Over SRv6
192 3.- N3 via SRv6 support of ID-LOC architecture
194 Important notes:
196 - The above phases and solution strategy can easily be extended to
197 the N9 interface. However, although the N9 interface is well
198 within the scope of this PoC, the effort required to changes the
199 OAI code base to support S5/S8 and separate SGW and PGW modules
200 will push the project well beyond the timeline of this PoC and as
201 such are not currently part of the PoC.
202 - Support for service programming, TE, QoS, entropy, and other
203 enhanced features are also within the scope of this PoC, but will
204 also fall beyond the time line of this project and are not
205 currently considered in this PoC.
206 - The above items can be pulled back into the project based on demand
207 and assistance from others.
209 4.1.1. Phase 1: Mobile Core Migration from IPv4-GTP to SRv6
211 Phase one of this POC focuses on demonstrating a smooth migration
212 path from the existing mobile core networks with IPv4 GTP based user
213 plane to SRv6 user plane with absolutely no impact on 3GPP control
214 plane. The idea is to employ SRv6 gateways between mobile core
215 equipment such as eNB, SGW, and PGW, intercept GTP traffic, and carry
216 UE's payload through SRv6 newtwork by encoding GTP information into
217 the SIDs.
219 In this POC as it was mentioned earlier we use OAI open source
220 software. OAI implements gNB as an stand alone entitiy, but bundles
221 MME, SGW and PGW into a single package. We employ three Linux PCs in
222 oursetup. Two of these machines run the gNB and one of the SRv6 GWs.
223 The thrid machines employs virtualisation and instantiates two
224 virtual machines. The second SRv6 gateway runs in one of the virtual
225 machine while the other virtual machines executes the code for the
226 combinged MME, SGW, PGW. The code in SRv6 gateways is based on VPP
227 implementation in Linux Foundation. We modified this code to
228 intercept GTP packets, extract GTP information, and encode GTP
229 information into the SIDs. Given that today's mobile core don't deal
230 with multiple UPFs, the resulting SRv6 haeader doesn't require any
231 SRH to carry GTP information across the network. Therefore, in this
232 phase, the resulting SRv6 packets are simply IPv6 packets with their
233 DA set to SIDs. The following diagratm shows the POC configuration.
235 +--------------------------+
236 | +========+|
237 +--+ \|/ | | +---+ ||
238 |UE| | | | |HSS| ||
239 +--+ | | | +-+-+ ||
240 +--+ | | | ||
241 | | | +-+-+ ||
242 +-+ | | |MME| ||
243 | | | +---+ ||
244 | GTP<->SID | GTP<->SID | ||
245 +---+---+ +-----+ +--------+ | +========+ |+------+||
246 | USRP | | | | | | | | || |||
247 |(Ettus +---+ gNB +-GTP--+ SRGW-1 +--SRv6-|-+ SRGW-2 +-GTP-|+ SPGW |||
248 | B210) | ^ | | | | | | | || |||
249 +-------+ | +-----+ +--------+ | +========+ |+--+---+||
250 | | VM-1 | | ||
251 USB | | | ||
252 | +========+|
253 | VM-2 | |
254 | | |
255 +--------------------|-----+
256 |
257 |
258 DN
260 POC Configuration
262 In this implementation, the SRGW at one end extracts relavant GTP
263 informaton(SA, DA, TEID) from GTP and encodes them into the lower 96
264 bits of SID. The SID is then copied into the DA of IPv6 header and
265 the packet is forwarded toward the SRGW at the far end. Receiving
266 the SRv6 packet, the far end SRGW recognises the SID as local and
267 executes a set of functions that extracts GTP information from the
268 SID, forms the GTP packet by adding relevant UDP and GTP headers and
269 forward this reconstructed GTP packet to its associated mobile core
270 node.
272 4.2. Activity report
274 Development started. Phase 1 has been completed.
276 5. Contributors
278 Chenchen Liu
279 Huawei Technolgies Co., Ltd.
280 Shenzhen, China
281 Email: liuchenchen1@huawei.com
283 Arun Rajagopal
284 Sprint
285 United States of America
287 Email: Arun.Rajagopal@sprint.com
289 Mark Bales
290 Sprint
291 United States of America
293 Email: Mark.Bales@sprint.com
295 Robert Butler
296 Sprint
297 United States of America
299 Email: Robert.Butler@sprint.com
301 6. Informative References
303 [I-D.filsfils-spring-srv6-network-programming]
304 Filsfils, C., Camarillo, P., Leddy, J.,
305 daniel.voyer@bell.ca, d., Matsushima, S., and Z. Li, "SRv6
306 Network Programming", draft-filsfils-spring-srv6-network-
307 programming-05 (work in progress), July 2018.
309 [I-D.ietf-dmm-srv6-mobile-uplane]
310 Matsushima, S., Filsfils, C., Kohno, M., Camarillo, P.,
311 daniel.voyer@bell.ca, d., and C. Perkins, "Segment Routing
312 IPv6 for Mobile User Plane", draft-ietf-dmm-srv6-mobile-
313 uplane-02 (work in progress), July 2018.
315 [TS.23501]
316 3GPP, "System Architecture for the 5G System", 3GPP TS
317 23.501 15.0.0, November 2017.
319 Authors' Addresses
321 Pablo Camarillo Garvia
322 Cisco Systems, Inc.
323 Spain
325 Email: pcamaril@cisco.com
326 Clarence Filsfils
327 Cisco Systems, Inc.
328 Belgium
330 Email: cf@cisco.com
332 Lyle T Bertz
333 Sprint
334 United States of America
336 Email: Lyle.T.Bertz@sprint.com
338 Arashmid Akhavain
339 Huawei Canada Research Centre
340 Canada
342 Email: arashmid.akhavain@huawei.com
344 Satoru Matsushima
345 SoftBank
346 Tokyo
347 Japan
349 Email: satoru.matsushima@g.softbank.co.jp
351 Daniel Voyer
352 Bell Canada
353 Canada
355 Email: daniel.voyer@bell.ca