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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 ALTO Y. Cao 3 Internet-Draft ZTE Corporation 4 Intended status: BCP L. Li 5 Expires: March 13, 2013 Unaffiliated 6 F. Zhang 7 ZTE Corporation 8 September 9, 2012 10 Hierarchical ALTO 11 draft-cao-alto-hierarchical-alto-00 13 Abstract 15 The ALTO Service allows applications to obtain network information 16 for optimizing their traffic. An ALTO server maintains ALTO data and 17 provides ALTO services to its clients. In a big network, a single 18 ALTO server could a bottleneck in performance. To increase the 19 scalability of ALTO, this document proposes a hierarchical 20 architecture for ALTO. This architecture allows collecting ALTO 21 information and/or providing ALTO services in a distributed manner. 22 An ISP can deploy multiple ALTO servers in a hierarchical 23 architecture to improve scalability. 25 Status of this Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at http://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on March 13, 2013. 42 Copyright Notice 44 Copyright (c) 2012 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. 54 Table of Contents 56 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 57 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 58 3. Hierarchical ALTO . . . . . . . . . . . . . . . . . . . . . . . 3 59 3.1. ALTO Data Collection Usage . . . . . . . . . . . . . . . . 4 60 3.2. ALTO Map Distribution Usage . . . . . . . . . . . . . . . . 5 61 3.3. ALTO Data Reflection Usage . . . . . . . . . . . . . . . . 6 62 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7 63 5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 64 5.1. Normative References . . . . . . . . . . . . . . . . . . . 7 65 5.2. Informative References . . . . . . . . . . . . . . . . . . 7 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 68 1. Introduction 70 The ALTO Service allows applications to obtain network information 71 for optimizing their traffic. The ALTO protocol 72 [I-D.ietf-alto-protocol] defines communications between an ALTO 73 client and an ALTO server. An ALTO server need to maintain ALTO 74 information and provides ALTO services to its clients. In a big 75 network, a single ALTO could a bottleneck in performance. Therefore, 76 [I-D.ietf-alto-protocol] proposes some mechanisms to improve 77 scalability including HTTP caching, application redistributing ALTO 78 inforamtion and deploying multiple ALTO servers. 79 [I-D.picconi-alto-home-proxy] discusses the use of ALTO proxies 80 running on home devices to improve scalabity, as well as reduce ALTO 81 traffic and query latency. [I-D.gu-alto-redistribution] discusses 82 P2P applications redistributing ALTO inforamtion. 84 To increase the scalability of ALTO, this document proposes a 85 hierarchical architecture for ALTO. This architecture allows 86 collecting ALTO information and/or providing ALTO services in a 87 distributed manner. An ISP can deploy multiple ALTO servers in a 88 hierarchical architecture to improve scalability. Compared with the 89 mechanism discussed in [I-D.gu-alto-redistribution], this mechanism 90 dosn't require the help from users or applications. This mechanism 91 considers not only the load of providing ALTO services, but also the 92 load of collecting and generating ALTO inforamtion. The same as 93 [I-D.dulinski-alto-inter-alto-protocol], this document invovles the 94 interface between ALTO servers. But 95 [I-D.dulinski-alto-inter-alto-protocol] and this document focus on 96 different scenarios, and address different issues. 97 [I-D.dulinski-alto-inter-alto-protocol] focuses on the relation 98 between ALTO servers from different ASes, while this document focuses 99 on the ALTO servers inside an ISP. 100 [I-D.dulinski-alto-inter-alto-protocol] addresses the issues about 101 inter-AS ALTO information exchange as dicussed in 102 [I-D.dulinski-alto-inter-problem-statement]. 104 2. Terminology 106 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 107 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 108 document are to be interpreted as described in RFC 2119 [RFC2119]. 110 3. Hierarchical ALTO 111 ,---------. 112 ,' top `. 113 /( ALTO ) 114 / '. server , 115 .' `---------' `. 116 / | \ 117 / | `. 118 / | \ 119 / | `. 120 / | `. 121 .' | \ 122 / | `. 123 O--------O O--------O O--------O 124 | bottom | | bottom | | bottom | 125 | ALTO | | ALTO | | ALTO | 126 | server | | server | | server | 127 O--------O O--------O O--------O 129 As shown in the figure above, there are two tiers of ALTO servers in 130 the hierarchical ALTO architecture. There are multiple ALTO servers 131 in the bottom tier, while there is only one ALTO server in the top 132 tier. ALTO servers in the bottom tier can collect maps and/or 133 provide ALTO services collectively. Three usages for the 134 hierarchical ALTO architecture are described as below. 136 3.1. ALTO Data Collection Usage 138 In this usage, ALTO data are collected and generated in a distributed 139 manner, while ALTO services are provided to ALTO clients in a 140 centralized manner. Each bottom ALTO server, i.e. ALTO server in 141 the bottom tier, is responsible for collecting some topology data and 142 generating a part of the ALTO maps. All bottom servers together send 143 all parts of the ALTO maps to the top ALTO server, i.e. the ALTO 144 server in the top tier. Only the top ALTO server has the whole ALTO 145 maps, and only the top ALTO server provides ALTO services to ALTO 146 clients. Bottom ALTO servers only provide services to the top ALTO 147 server. Bottom ALTO servers could be dedicated servers or coupled 148 with routers. 150 ,---------. 151 ,' top `. 152 /( ALTO ) 153 / '. server ,__ 154 .' / `----+----'|`. 155 / / /|\ \send 156 / / |send `.part 157 / / |part \ of 158 / / | of `.ALTO 159 / | |ALTO `.maps 160 .' | |maps \ 161 / | | `. 162 O---+----O | O--------O O--------O 163 | bottom | | | bottom | | bottom | 164 | ALTO | | | ALTO | | ALTO | 165 | server | | | server | | server | 166 O--------O | O--------O O--------O 167 | 168 | 169 +--+----+ 170 | ALTO | 171 |client | 172 +-------+ 174 3.2. ALTO Map Distribution Usage 176 In this usage, ALTO data are generated in a centralized manner, while 177 ALTO services are provided to ALTO clients in a distributed manner. 178 The top ALTO server is responsible for collecting all topology data 179 and generating the ALTO maps. The top ALTO server distributes the 180 ALTO maps to all bottom ALTO servers. Both the top ALTO server and 181 the bottom ALTO servers have the ALTO maps. All ALTO servers or only 182 the bottom ALTO servers provide ALTO services to ALTO clients. 184 ,---------. 185 ,' top `. 186 /( ALTO ) 187 / '. server , 188 .' `---------' `. 189 / | \ 190 / |send `. 191 / | the \ 192 / |whole `. 193 / |ALTO `. 194 .' |maps \ 195 / \|/ \ 196 O---+----O O--------O O--------O 197 | bottom | | bottom | | bottom | 198 | ALTO | | ALTO | | ALTO | 199 | server | | server | | server | 200 O---+----O O--+-----O O+-------O 201 | | | 202 | | | 203 +--+----+ +--+----+ +--+----+ 204 | ALTO | | ALTO | | ALTO | 205 |client | |client | |client | 206 +-------+ +-------+ +-------+ 208 3.3. ALTO Data Reflection Usage 210 In this usage, ALTO data are generated in a distributed manner, and 211 ALTO services are provided to ALTO clients also in a distributed 212 manner. Each bottom ALTO server is responsible for collecting some 213 topology data and generating a part of the ALTO maps. All bottom 214 ALTO servers together send all parts of the ALTO maps to the top ALTO 215 server. Then the top ALTO server distributes the whole ALTO maps to 216 all bottom servers. All ALTO servers have the whole ALTO maps. All 217 ALTO servers or only the bottom ALTO servers provide ALTO services to 218 ALTO clients. When receiving ALTO map update from a bottom ALTO 219 server, the top ALTO server sends update data to the other bottom 220 ALTO servers like a reflector of ALTO data. 222 ,---------. 223 ,' top `. 224 /( ALTO ) 225 / '. server ,__ 226 .' `---------'|`. 227 / | \send 228 / |send `.part 229 / | the \ of 230 / |whole `.ALTO 231 / |ALTO `.maps 232 .' |maps \ 233 / \|/ \ 234 O---+----O O--------O O--------O 235 | bottom | | bottom | | bottom | 236 | ALTO | | ALTO | | ALTO | 237 | server | | server | | server | 238 O---+----O O--+-----O O+-------O 239 | | | 240 | | | 241 +--+----+ +--+----+ +--+----+ 242 | ALTO | | ALTO | | ALTO | 243 |client | |client | |client | 244 +-------+ +-------+ +-------+ 246 4. Security Considerations 248 TBD 250 5. References 252 5.1. Normative References 254 [I-D.ietf-alto-protocol] 255 Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol", 256 draft-ietf-alto-protocol-13 work in progress, 257 September 2012. 259 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 260 Requirement Levels", BCP 14, RFC 2119, March 1997. 262 5.2. Informative References 264 [I-D.dulinski-alto-inter-alto-protocol] 265 Dulinski, Z., Stankiewicz, R., Cholda, P., Wydrych, P., 266 and B. Stiller, "Inter-ALTO communication protocol", 267 draft-dulinski-alto-inter-alto-protocol-00 work in 268 progress, June 2010. 270 [I-D.dulinski-alto-inter-problem-statement] 271 Alimi, R., Penno, R., and Y. Yang, "Inter-ALTO 272 Communication Problem Statement", 273 draft-dulinski-alto-inter-problem-statement-01 work in 274 progress, July 2011. 276 [I-D.gu-alto-redistribution] 277 Gu, Y., Alimi, R., and R. Even, "ALTO Information 278 Redistribution", draft-gu-alto-redistribution-03 work in 279 progress, July 2010. 281 [I-D.picconi-alto-home-proxy] 282 Picconi, F., "ALTO home proxy", 283 draft-picconi-alto-home-proxy-00 work in progress, 284 October 2011. 286 Authors' Addresses 288 Yalin Cao 289 ZTE Corporation 290 RD Building 1,Zijinghua Road No.68 291 Yuhuatai District,Nanjing 210012 292 P.R.China 294 Email: cao.yalin1@zte.com.cn 296 Lichun Li 297 Unaffiliated 299 Email: lilichun@gmail.com 301 Fei Zhang 302 ZTE Corporation 303 RD Building 1,Zijinghua Road No.68 304 Yuhuatai District,Nanjing 210012 305 P.R.China 307 Email: zhang.fei3@zte.com.cn