Internet DRAFT - draft-cao-alto-hierarchical-alto
draft-cao-alto-hierarchical-alto
ALTO Y. Cao
Internet-Draft ZTE Corporation
Intended status: BCP L. Li
Expires: March 13, 2013 Unaffiliated
F. Zhang
ZTE Corporation
September 9, 2012
Hierarchical ALTO
draft-cao-alto-hierarchical-alto-00
Abstract
The ALTO Service allows applications to obtain network information
for optimizing their traffic. An ALTO server maintains ALTO data and
provides ALTO services to its clients. In a big network, a single
ALTO server could a bottleneck in performance. To increase the
scalability of ALTO, this document proposes a hierarchical
architecture for ALTO. This architecture allows collecting ALTO
information and/or providing ALTO services in a distributed manner.
An ISP can deploy multiple ALTO servers in a hierarchical
architecture to improve scalability.
Status of this Memo
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This Internet-Draft will expire on March 13, 2013.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Hierarchical ALTO . . . . . . . . . . . . . . . . . . . . . . . 3
3.1. ALTO Data Collection Usage . . . . . . . . . . . . . . . . 4
3.2. ALTO Map Distribution Usage . . . . . . . . . . . . . . . . 5
3.3. ALTO Data Reflection Usage . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
5. References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
5.1. Normative References . . . . . . . . . . . . . . . . . . . 7
5.2. Informative References . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
The ALTO Service allows applications to obtain network information
for optimizing their traffic. The ALTO protocol
[I-D.ietf-alto-protocol] defines communications between an ALTO
client and an ALTO server. An ALTO server need to maintain ALTO
information and provides ALTO services to its clients. In a big
network, a single ALTO could a bottleneck in performance. Therefore,
[I-D.ietf-alto-protocol] proposes some mechanisms to improve
scalability including HTTP caching, application redistributing ALTO
inforamtion and deploying multiple ALTO servers.
[I-D.picconi-alto-home-proxy] discusses the use of ALTO proxies
running on home devices to improve scalabity, as well as reduce ALTO
traffic and query latency. [I-D.gu-alto-redistribution] discusses
P2P applications redistributing ALTO inforamtion.
To increase the scalability of ALTO, this document proposes a
hierarchical architecture for ALTO. This architecture allows
collecting ALTO information and/or providing ALTO services in a
distributed manner. An ISP can deploy multiple ALTO servers in a
hierarchical architecture to improve scalability. Compared with the
mechanism discussed in [I-D.gu-alto-redistribution], this mechanism
dosn't require the help from users or applications. This mechanism
considers not only the load of providing ALTO services, but also the
load of collecting and generating ALTO inforamtion. The same as
[I-D.dulinski-alto-inter-alto-protocol], this document invovles the
interface between ALTO servers. But
[I-D.dulinski-alto-inter-alto-protocol] and this document focus on
different scenarios, and address different issues.
[I-D.dulinski-alto-inter-alto-protocol] focuses on the relation
between ALTO servers from different ASes, while this document focuses
on the ALTO servers inside an ISP.
[I-D.dulinski-alto-inter-alto-protocol] addresses the issues about
inter-AS ALTO information exchange as dicussed in
[I-D.dulinski-alto-inter-problem-statement].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
3. Hierarchical ALTO
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,---------.
,' top `.
/( ALTO )
/ '. server ,
.' `---------' `.
/ | \
/ | `.
/ | \
/ | `.
/ | `.
.' | \
/ | `.
O--------O O--------O O--------O
| bottom | | bottom | | bottom |
| ALTO | | ALTO | | ALTO |
| server | | server | | server |
O--------O O--------O O--------O
As shown in the figure above, there are two tiers of ALTO servers in
the hierarchical ALTO architecture. There are multiple ALTO servers
in the bottom tier, while there is only one ALTO server in the top
tier. ALTO servers in the bottom tier can collect maps and/or
provide ALTO services collectively. Three usages for the
hierarchical ALTO architecture are described as below.
3.1. ALTO Data Collection Usage
In this usage, ALTO data are collected and generated in a distributed
manner, while ALTO services are provided to ALTO clients in a
centralized manner. Each bottom ALTO server, i.e. ALTO server in
the bottom tier, is responsible for collecting some topology data and
generating a part of the ALTO maps. All bottom servers together send
all parts of the ALTO maps to the top ALTO server, i.e. the ALTO
server in the top tier. Only the top ALTO server has the whole ALTO
maps, and only the top ALTO server provides ALTO services to ALTO
clients. Bottom ALTO servers only provide services to the top ALTO
server. Bottom ALTO servers could be dedicated servers or coupled
with routers.
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,---------.
,' top `.
/( ALTO )
/ '. server ,__
.' / `----+----'|`.
/ / /|\ \send
/ / |send `.part
/ / |part \ of
/ / | of `.ALTO
/ | |ALTO `.maps
.' | |maps \
/ | | `.
O---+----O | O--------O O--------O
| bottom | | | bottom | | bottom |
| ALTO | | | ALTO | | ALTO |
| server | | | server | | server |
O--------O | O--------O O--------O
|
|
+--+----+
| ALTO |
|client |
+-------+
3.2. ALTO Map Distribution Usage
In this usage, ALTO data are generated in a centralized manner, while
ALTO services are provided to ALTO clients in a distributed manner.
The top ALTO server is responsible for collecting all topology data
and generating the ALTO maps. The top ALTO server distributes the
ALTO maps to all bottom ALTO servers. Both the top ALTO server and
the bottom ALTO servers have the ALTO maps. All ALTO servers or only
the bottom ALTO servers provide ALTO services to ALTO clients.
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,---------.
,' top `.
/( ALTO )
/ '. server ,
.' `---------' `.
/ | \
/ |send `.
/ | the \
/ |whole `.
/ |ALTO `.
.' |maps \
/ \|/ \
O---+----O O--------O O--------O
| bottom | | bottom | | bottom |
| ALTO | | ALTO | | ALTO |
| server | | server | | server |
O---+----O O--+-----O O+-------O
| | |
| | |
+--+----+ +--+----+ +--+----+
| ALTO | | ALTO | | ALTO |
|client | |client | |client |
+-------+ +-------+ +-------+
3.3. ALTO Data Reflection Usage
In this usage, ALTO data are generated in a distributed manner, and
ALTO services are provided to ALTO clients also in a distributed
manner. Each bottom ALTO server is responsible for collecting some
topology data and generating a part of the ALTO maps. All bottom
ALTO servers together send all parts of the ALTO maps to the top ALTO
server. Then the top ALTO server distributes the whole ALTO maps to
all bottom servers. All ALTO servers have the whole ALTO maps. All
ALTO servers or only the bottom ALTO servers provide ALTO services to
ALTO clients. When receiving ALTO map update from a bottom ALTO
server, the top ALTO server sends update data to the other bottom
ALTO servers like a reflector of ALTO data.
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,---------.
,' top `.
/( ALTO )
/ '. server ,__
.' `---------'|`.
/ | \send
/ |send `.part
/ | the \ of
/ |whole `.ALTO
/ |ALTO `.maps
.' |maps \
/ \|/ \
O---+----O O--------O O--------O
| bottom | | bottom | | bottom |
| ALTO | | ALTO | | ALTO |
| server | | server | | server |
O---+----O O--+-----O O+-------O
| | |
| | |
+--+----+ +--+----+ +--+----+
| ALTO | | ALTO | | ALTO |
|client | |client | |client |
+-------+ +-------+ +-------+
4. Security Considerations
TBD
5. References
5.1. Normative References
[I-D.ietf-alto-protocol]
Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol",
draft-ietf-alto-protocol-13 work in progress,
September 2012.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
5.2. Informative References
[I-D.dulinski-alto-inter-alto-protocol]
Dulinski, Z., Stankiewicz, R., Cholda, P., Wydrych, P.,
and B. Stiller, "Inter-ALTO communication protocol",
draft-dulinski-alto-inter-alto-protocol-00 work in
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progress, June 2010.
[I-D.dulinski-alto-inter-problem-statement]
Alimi, R., Penno, R., and Y. Yang, "Inter-ALTO
Communication Problem Statement",
draft-dulinski-alto-inter-problem-statement-01 work in
progress, July 2011.
[I-D.gu-alto-redistribution]
Gu, Y., Alimi, R., and R. Even, "ALTO Information
Redistribution", draft-gu-alto-redistribution-03 work in
progress, July 2010.
[I-D.picconi-alto-home-proxy]
Picconi, F., "ALTO home proxy",
draft-picconi-alto-home-proxy-00 work in progress,
October 2011.
Authors' Addresses
Yalin Cao
ZTE Corporation
RD Building 1,Zijinghua Road No.68
Yuhuatai District,Nanjing 210012
P.R.China
Email: cao.yalin1@zte.com.cn
Lichun Li
Unaffiliated
Email: lilichun@gmail.com
Fei Zhang
ZTE Corporation
RD Building 1,Zijinghua Road No.68
Yuhuatai District,Nanjing 210012
P.R.China
Email: zhang.fei3@zte.com.cn
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