One document matched: draft-sun-alto-notification-00.txt
ALTO X. Sun
Internet-Draft K. Li
Intended status: Standards Track K. Zhou
Expires: August 26, 2010 China Telecom
February 26, 2010
Server Notification mechanism for ALTO optimization
draft-sun-alto-notification-00.txt
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Sun, et al. Expires August 26, 2010 [Page 1]
Internet-Draft Server Notification mechanism February 2010
Abstract
Application-Layer Traffic Optimization (ALTO) guides an application,
especially a Peer to Peer (P2P) application, to select hosts from
its candidate set. ALTO is a promising technique for future network,
as it is able to jointly optimize network resource utilization and
application performance. The ALTO protocol is Client-Server based.
Applications work as ALTO clients to fetch PID information from the
ALTO server, but the ALTO server can't send the notification to ALTO
clients, even if there is a major change to the networks. This draft
discusses the requirements for server initialized notification, and
proposes one mechanism to enable the ALTO server notification.
Table of Contents
1. Introduction ................................................ 2
2. Problem statement ........................................... 3
3. Requirement ................................................. 3
4. Server initiating notification mechanism .................... 3
4.1. The processing ......................................... 4
4.2. Message format ......................................... 5
5. Security Considerations ..................................... 5
6. IANA Considerations ......................................... 5
7. References .................................................. 5
Author's Addresses ............................................. 6
1. Introduction
Application Layer Traffic Optimization (ALTO) provides a solution
benefits both Internet Service Provider (ISP) and P2P
operators/applications. In this solution, P2P applications utilize
network information provided by ALTO service to optimize its traffic.
However, the current ALTO mechanism depends on ALTO clients fetching
network information from the servers, and neglects the requirements
to proactively dispatching such information. Unfortunately, there
are some scenarios that rapid dispatching of network information is
valuable.
In this draft, one mechanism is proposed to dispatch the newest
network information from ALTO server to ALTO clients quickly. It
will let P2P applications know the new network information. The
performance of peer selection and ISP traffic management will be
improved.
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Internet-Draft Server Notification mechanism February 2010
Because traffic generated by tracker indexed P2P applications
predominates current P2P networks. This draft considers only the
server notification implementation based on tracker indexed P2P
applications.
2. Problem statement
ALTO enhances the traffic optimization capability of ISPs. However,
networks and the optimization policy of ISPs are changing frequently.
Current ALTO protocol uses B/S architecture. ALTO server is the
passive side, and there is only one direction of ALTO message
process. ALTO clients send query message periodically to ALTO server
for the network and optimization information. This kind of passive
mode cannot response quickly to network or ISP's network provision
policy change. When a network change occurs, although the ISP
updates the ALTO server simultaneously, P2P traffic keeps following
the guidance of the previous ALTO direction, as ALTO clients have no
knowledge of the change. This will cause a period of pressure to ISP
network and raises maintenance problems.
3. Requirement
Whenever the change of network condition leads to the change of
network map and cost map in ALTO server, the ALTO server SHOULD
notify the change to ALTO clients as quickly as possible, and need
not wait for the ALTO query message of next period as illustrated in
current ALTO protocol.
4. Server initiating notification mechanism
In this mechanism, ALTO server will maintain one table to record the
address information about each ALTO client. ALTO server will
initiate the notification message connection using the address
information. The address information will be used to identify the
ALTO client, which can be the IP address/port or the URL of tracker
which has the ALTO client. In order to improve the ALTO server's
efficiency, only P2P tracker and application server will be notified
by ALTO server.
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Internet-Draft Server Notification mechanism February 2010
One new ALTO message is added in this mechanism, notification
message. The source of the message is the ALTO server, and the
destination is the ALTO client which recorded in the table.
HTTP protocol is used to build notification message. One lightweight
HTTP server module is needed in ALTO client to receive notification
message, as well as HTTP client is needed in the ALTO server.
4.1. The processing
When network condition changes, the ALTO server will refresh its
network map and cost map according to the related policy. Once the
update is finished, ALTO server will build the notification message
and send to the ALTO clients. When ALTO client receives the
notification message, it will send the ALTO query message
immediately to get the renewed network/cost map. This ALTO query
message is the same with the current ALTO protocol. When ALTO client
receives the notification message, it need not send any response
message.
+---------------+ +---------------+ +----------------+
|P2P Tracker/ | | | | Network |
|ALTO client | |ALTO server | | condition |
+---------------+ +-------+-------+ +----------------+
| | |
| | Network changing |
| <---------------------+
| | \\ |
| | | Map refresh |
| Notification message| // |
<---------------------|- |
| | |
| | |
| Query message | |
+---------------------> |
| | |
| | |
| Response message | |
<---------------------+ |
| | |
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Internet-Draft Server Notification mechanism February 2010
4.2. Message format
The notification message format is as below.
Method : 'POST'
URI Path : '/notification'
5. Security Considerations
High-level security considerations can be found in the [draft-ietf-
alto-problem-statement].
6. IANA Considerations
This document does not mandate any immediate IANA actions.
7. References
[RFC 5693]
Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693,
October 2009.
[I-D.ietf-alto-reqs]
Kiesel, S., Popkin, L., Previdi, S., Woundy, R., and Y.
Yang, "Application-Layer Traffic Optimization (ALTO)
Requirements", draft-ietf-alto-reqs-01 (work in
progress),July 2009.
[I-D.penno-alto-protocol]
Penno, R. and Y. Yang, "ALTO Protocol",
draft-ietf-alto-protocol-01 (work in progress),
July 2009.
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Author's Addresses
Xianghui Sun
China Telecom Beijing Research Institute
No.118, Xizhimenneidajie, xicheng District
Beijing 100035
China
Email: sunxh@ctbri.com.cn
Kai Li
China Telecom Beijing Research Institute
No.118, Xizhimenneidajie, xicheng District
Beijing 100035
China
Email: leekai@ctbri.com.cn
Kaiyu Zhou
China Telecom Beijing Research Institute
No.118, Xizhimenneidajie, xicheng District
Beijing 100035
China
Email: zhouky@ctbri.com.cn
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