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2 Spring J. Brzozowski
3 Internet-Draft J. Leddy
4 Intended status: Informational Comcast
5 Expires: June 21, 2018 C. Filsfils
6 R. Maglione, Ed.
7 M. Townsley
8 Cisco Systems
9 December 18, 2017
11 IPv6 SPRING Use Cases
12 draft-ietf-spring-ipv6-use-cases-12
14 Abstract
16 The Source Packet Routing in Networking (SPRING) architecture
17 describes how Segment Routing can be used to steer packets through an
18 IPv6 or MPLS network using the source routing paradigm. This
19 document illustrates some use cases for Segment Routing in an IPv6
20 only environment.
22 Status of This Memo
24 This Internet-Draft is submitted in full conformance with the
25 provisions of BCP 78 and BCP 79.
27 Internet-Drafts are working documents of the Internet Engineering
28 Task Force (IETF). Note that other groups may also distribute
29 working documents as Internet-Drafts. The list of current Internet-
30 Drafts is at https://datatracker.ietf.org/drafts/current/.
32 Internet-Drafts are draft documents valid for a maximum of six months
33 and may be updated, replaced, or obsoleted by other documents at any
34 time. It is inappropriate to use Internet-Drafts as reference
35 material or to cite them other than as "work in progress."
37 This Internet-Draft will expire on June 21, 2018.
39 Copyright Notice
41 Copyright (c) 2017 IETF Trust and the persons identified as the
42 document authors. All rights reserved.
44 This document is subject to BCP 78 and the IETF Trust's Legal
45 Provisions Relating to IETF Documents
46 (https://trustee.ietf.org/license-info) in effect on the date of
47 publication of this document. Please review these documents
48 carefully, as they describe your rights and restrictions with respect
49 to this document. Code Components extracted from this document must
50 include Simplified BSD License text as described in Section 4.e of
51 the Trust Legal Provisions and are provided without warranty as
52 described in the Simplified BSD License.
54 Table of Contents
56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
57 2. IPv6 SPRING use cases . . . . . . . . . . . . . . . . . . . . 2
58 2.1. SPRING in the Small Office . . . . . . . . . . . . . . . 2
59 2.2. SPRING in the Access Network . . . . . . . . . . . . . . 4
60 2.3. SPRING in Data Center . . . . . . . . . . . . . . . . . . 4
61 2.4. SPRING in Content Delivery Networks . . . . . . . . . . . 5
62 2.5. SPRING in Core networks . . . . . . . . . . . . . . . . . 5
63 3. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 6
64 4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
65 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
66 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
67 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
68 7.1. Informative References . . . . . . . . . . . . . . . . . 8
69 7.2. Normative References . . . . . . . . . . . . . . . . . . 8
70 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
72 1. Introduction
74 Source Packet Routing in Networking (SPRING) architecture leverages
75 the source routing paradigm. An ingress node steers a packet by
76 including a controlled set of instructions, called segments, in the
77 SPRING header. The SPRING architecture is described in
78 [I-D.ietf-spring-segment-routing]. This document illustrates some
79 use cases for SPRING/Segment Routing in an IPv6 only environment.
81 2. IPv6 SPRING use cases
83 The use cases described in the section do not constitute an
84 exhaustive list of all the possible scenarios: this section only
85 includes some of the most common envisioned deployment models for
86 IPv6 Segment Routing.
88 In addition to the use cases described in this document, all the
89 SPRING use cases [RFC7855] are also applicable to the SRv6 data
90 plane.
92 2.1. SPRING in the Small Office
94 An IPv6-enabled small office (SOHO) provides ample globally routed IP
95 addresses for all devices in the SOHO. An IPv6 small office with
96 multiple egress points and associated provider-assigned prefixes
97 will, in turn, provide multiple IPv6 addresses to hosts. A small
98 office performing Source and Destination Routing
99 ([I-D.ietf-rtgwg-enterprise-pa-multihoming]) will ensure that packets
100 exit the SOHO at the appropriate egress based on the associated
101 delegated prefix for that link.
103 A SPRING enabled SOHO provides the ability to steer traffic into a
104 specific path from end-hosts in the SOHO, or from a customer edge
105 router in the SOHO. If the selection of the source routed path is
106 enabled at the customer edge router, that router is responsible for
107 classifying traffic and steering it into the correct path. If hosts
108 in the SOHO have explicit source selection rules, classification can
109 be based on source address or associated network egress point,
110 avoiding the need for DPI-based implicit classification techniques.
111 If the traffic is steered into a specific path by the host itself, it
112 is important to know which networks can interpret the SPRING header.
113 This information can be provided as part of host configuration as a
114 property of the configured IP address.
116 The ability to steer traffic to an appropriate egress or utilize a
117 specific type of media (e.g., low-power, WIFI, wired, femto-cell,
118 bluetooth, MOCA, HomePlug, etc.) within the home itself are obvious
119 cases which may be of interest to an application running within a
120 SOHO.
122 Steering to a specific egress point may be useful for a number of
123 reasons, including:
125 o Regulatory
127 o Performance of a particular service associated with a particular
128 link
130 o Cost imposed due to data-caps or per-byte charges
132 o Home vs. work traffic in homes with one or more teleworkers, etc.
134 o Specific services provided by one ISP vs. another
136 Information included in the SPRING header, whether imposed by the
137 end-host itself, a customer edge router, or within the access network
138 of the ISP, may be of use at the far ends of the data communication
139 as well. For example, an application running on an end-host with
140 application-support in a data center can utilize the SPRING header as
141 a channel to include information that affects its treatment within
142 the data center itself, allowing for application-level steering and
143 load-balancing without relying upon implicit application
144 classification techniques at the data-center edge. Further, as more
145 and more application traffic is encrypted, the ability to extract
146 (and include in the SPRING header) just enough information to enable
147 the network and data center to load-balance and steer traffic
148 appropriately becomes more and more important.
150 2.2. SPRING in the Access Network
152 Access networks deliver a variety of types of traffic from the
153 service provider's network to the home environment and from the home
154 towards the service provider's network.
156 For bandwidth management or related purposes, the service provider
157 may want to associate certain types of traffic to specific physical
158 or logical downstream capacity pipes.
160 This mapping is not the same thing as classification and scheduling.
161 In the Cable access network, each of these pipes are represented at
162 the DOCSIS [DOCSIS] layer as different service flows, which are
163 better identified as differing data links. As such, creating this
164 separation allows an operator to differentiate between different
165 types of content and perform a variety of differing functions on
166 these pipes, such as byte capping, regulatory compliance functions,
167 and billing.
169 In a cable operator's environment, these downstream pipes could be a
170 specific QAM (Quadrature Amplitude Modulation) [QAM], a DOCSIS (Data
171 Over Cable Service Interface Specification) [DOCSIS] service flow or
172 a service group.
174 Similarly, the operator may want to map traffic from the home sent
175 towards the service provider's network to specific upstream capacity
176 pipes. Information carried in a packet's SPRING header could provide
177 the target pipe for this specific packet. The access device would
178 not need to know specific details about the packet to perform this
179 mapping; instead the access device would only need to know the
180 interpretation of the SPRING header and how to map it to the target
181 pipe.
183 2.3. SPRING in Data Center
185 Some Data Center operators are transitioning their Data Center
186 infrastructure from IPv4 to native IPv6 only, in order to cope with
187 IPv4 address depletion and to achieve larger scale. In such
188 environment, source routing, as enabled by Segment Routing IPv6, can
189 be used to steer traffic across specific paths through the network.
190 The specific path may also include a given function one or more nodes
191 in the path are requested to perform.
193 In addition one of the fundamental requirements for Data Center
194 architecture is to provide scalable, isolated tenant networks. In
195 such scenarios, Segment Routing can be used to identify specific
196 nodes, tenants, and functions and to build a construct to steer the
197 traffic across that specific path.
199 2.4. SPRING in Content Delivery Networks
201 The rise of online video applications and new, video-capable IP
202 devices has led to an explosion of video traffic traversing network
203 operator infrastructures. In the drive to reduce the capital and
204 operational impact of the massive influx of online video traffic, as
205 well as to extend traditional TV services to new devices and screens,
206 network operators are increasingly turning to Content Delivery
207 Networks (CDNs).
209 Several studies showed the benefits of connecting caches in a
210 hierarchical structure following the hierarchical nature of the
211 Internet. In a cache hierarchy one cache establishes peering
212 relationships with its neighbor caches. There are two types of
213 relationship: parent and sibling. A parent cache is essentially one
214 level up in a cache hierarchy. A sibling cache is on the same level.
215 Multiple levels of hierarchy are commonly used in order to build
216 efficient caches architecture.
218 In an environment, where each single cache system can be uniquely
219 identified by its own IPv6 address, a list containing a sequence of
220 the caches in a hierarchy can be built. At each node (cache) in the
221 list, the presence of the requested content is checked. If the
222 requested content is found at the cache (cache hits scenario) the
223 sequence ends, even if there are more nodes in the list; otherwise
224 next element in the list (next node/cache) is examined.
226 2.5. SPRING in Core networks
228 While the overall amount of traffic offered to the network continues
229 to grow and considering that multiple types of traffic with different
230 characteristics and requirements are quickly converging over single
231 network architecture, the network operators are starting to face new
232 challenges.
234 Some operators are currently building, or plan to build in the near
235 future, an IPv6 only native infrastructure for their core network.
236 These operators are also looking at the possibility to setup an
237 explicit path based on the IPv6 source address for specific types of
238 traffic in order to efficiently use their network infrastructure. In
239 case of IPv6 some operators are currently assigning or plan to assign
240 IPv6 prefix(es) to their IPv6 customers based on regions/geography,
241 thus the subscriber's IPv6 prefix could be used to identify the
242 region where the customer is located. In such environment the IPv6
243 source address could be used by the Edge nodes of the network to
244 steer traffic and forward it through a specific path other than the
245 optimal path.
247 The need to setup a source-based path, going through some specific
248 middle/intermediate points in the network may be related to different
249 requirements:
251 o The operator may want to be able to use some high bandwidth links
252 for specific type of traffic (like video) avoiding the need for
253 over-dimensioning all the links of the network;
255 o The operator may want to be able to setup a specific path for
256 delay sensitive applications;
258 o The operator may have the need to be able to select one (or
259 multiple) specific exit point(s) at peering points when different
260 peering points are available;
262 o The operator may have the need to be able to setup a source based
263 path for specific services in order to be able to reach some
264 servers hosted in some facilities not always reachable through the
265 optimal path;
267 o The operator may have the need to be able to provision guaranteed
268 disjoint paths (so-called dual-plane network) for diversity
269 purposes
271 All these scenarios would require a form of traffic engineering
272 capabilities in an IPv6 only network environment.
274 3. Contributors
276 Many people contributed to this document. The authors of this
277 document would like to thank and recognize them and their
278 contributions. These contributors provided invaluable concepts and
279 content for this document's creation.
281 Ida Leung
282 Rogers Communications
283 8200 Dixie Road
284 Brampton, ON L6T 0C1
285 CANADA
287 Email: Ida.Leung@rci.rogers.com
289 Stefano Previdi
290 Cisco Systems
291 Via Del Serafico, 200
292 Rome 00142
293 Italy
295 Email: sprevidi@cisco.com
297 Christian Martin
298 Cisco Systems
300 Email: martincj@cisco.com
302 4. Acknowledgements
304 The authors would like to thank Brian Field, Robert Raszuk, Wes
305 George, Eric Vyncke, Fred Baker, John G. Scudder, Adrian Farrel,
306 Alvaro Retana, Bruno Decraene and Yakov Rekhter for their valuable
307 comments and inputs to this document.
309 5. IANA Considerations
311 This document does not require any action from IANA.
313 6. Security Considerations
315 This document presents use cases to be considered by the SPRING
316 architecture and potential IPv6 extensions. As such, it does not
317 introduce any security considerations. However, there are a number
318 of security concerns with source routing at the IP layer [RFC5095].
319 It is expected that any solution that addresses these use cases to
320 also address any security concerns.
322 7. References
324 7.1. Informative References
326 [DOCSIS] "DOCSIS Specifications Page",
327 .
330 [I-D.ietf-rtgwg-enterprise-pa-multihoming]
331 Baker, F., Bowers, C., and J. Linkova, "Enterprise
332 Multihoming using Provider-Assigned Addresses without
333 Network Prefix Translation: Requirements and Solution",
334 draft-ietf-rtgwg-enterprise-pa-multihoming-02 (work in
335 progress), October 2017.
337 [I-D.ietf-spring-segment-routing]
338 Filsfils, C., Previdi, S., Ginsberg, L., Decraene, B.,
339 Litkowski, S., and R. Shakir, "Segment Routing
340 Architecture", draft-ietf-spring-segment-routing-13 (work
341 in progress), October 2017.
343 [QAM] "QAM specification", .
346 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation
347 of Type 0 Routing Headers in IPv6", RFC 5095,
348 DOI 10.17487/RFC5095, December 2007,
349 .
351 7.2. Normative References
353 [RFC7855] Previdi, S., Ed., Filsfils, C., Ed., Decraene, B.,
354 Litkowski, S., Horneffer, M., and R. Shakir, "Source
355 Packet Routing in Networking (SPRING) Problem Statement
356 and Requirements", RFC 7855, DOI 10.17487/RFC7855, May
357 2016, .
359 Authors' Addresses
361 John Brzozowski
362 Comcast
364 Email: john_brzozowski@cable.comcast.com
365 John Leddy
366 Comcast
368 Email: John_Leddy@cable.comcast.com
370 Clarence Filsfils
371 Cisco Systems
372 Brussels
373 BE
375 Email: cfilsfil@cisco.com
377 Roberta Maglione (editor)
378 Cisco Systems
379 Via Torri Bianche 8
380 Vimercate 20871
381 Italy
383 Email: robmgl@cisco.com
385 Mark Townsley
386 Cisco Systems
388 Email: townsley@cisco.com