ALTO X. Sun
Internet-Draft China Telecom
Intended status: Informational Y. Yang
Expires: September 14, 2011 Yale University
March 14, 2011
ALTO Deployment Considerations: Configuration and Monitoring by ISPs
draft-sun-alto-ispdeployment-01.txt
Abstract
As ALTO specification continues in the ALTO Working Group and some
applications start to conduct integration with ALTO, more ISPs
start to evaluate key issues in the deployment of ALTO in their
networks. In this document, we discuss key issues that an ISP
needs to consider when deploying ALTO. In particular, we discuss
issues on how to configure ALTO information as well as how to
monitor the effectiveness of ALTO.
Requirements Language
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 [1].
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Table of Contents
1. Introduction ................................................ 2
2. ALTO Service Configuration................................... 3
2.1. Optimization Area....................................... 3
2.2. Network and Cost Map Configuration...................... 4
2.2.1. Network Map and PID................................ 4
2.2.2. Cost Map .......................................... 5
2.3. Endpoint Service Configuration.......................... 5
3. ALTO Deployment Monitoring................................... 6
3.1. Monitoring Metrics...................................... 6
3.1.1. Network Metrics.................................... 6
3.1.2. Application Metrics................................ 7
3.2. Monitoring Data Sources................................. 7
3.2.1. Application Log Server............................. 7
3.2.2. P2P Clients........................................ 7
3.2.3. OAM ............................................... 8
3.3. Application/ISP Monitoring Integration.................. 8
3.3.1. Structure ......................................... 8
3.3.2. ALTO Monitoring Report Protocol.................... 8
4. IANA Considerations ......................................... 8
5. Security Considerations...................................... 9
6. References .................................................. 9
6.1. Normative References.................................... 9
6.2. Informative References.................................. 9
1. Introduction
A basic service of ALTO is to provide information from network
service providers to applications, in order to improve network
efficiency and application performance. Some applications start to
or have shown interests to conduct integration with ALTO. Some
major ISPs (e.g., China Telecom) are in the process of deploying
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ALTO services in their production networks. As a result, more ISPs
start to evaluate key issues in the deployment of ALTO in their
networks. Thus, a document highlighting some key issues that an ISP
should consider in the deployment process can be a highly valuable
reference.
The objective of this document is to provide such a reference. The
document will try to draw on many valuable discussions in the ALTO
mailing list as well as the predecessor p2pi mailing list. In
addition, it will try to draw on the trial experiences of multiple
ISPs (e.g., [CTTrial,ComcastTrial].
The deployment of ALTO involves both ISPs and network applications.
We can identify four major issues in ALTO deployment:
1. How does an ISP deploy and configure its ALTO servers?
Specifically, an ALTO Server provides the Network Map and the
Cost Map. How does an ISP configure these maps? Where does an
ISP deploy ALTO servers?
2. Which application entities fetch ALTO information?
3. How does an application integrate ALTO information into its
decision process?
4. How does an ISP (potentially with collaboration from
applications) monitor the deployment of ALTO, so that the ISP
can better understand the status as well as the policy impacts
of its ALTO deployment?
This document focuses more on the ISP perspective. Therefore, it
focuses more on the first and the fourth issues. There are
additional deployment documents in the ALTO working group that
focus more on the second issue and the third issue. Our document
is complementary to these other documents.
2. ALTO Service Configuration
2.1. Optimization Area
An ISP deploys ALTO service to optimize traffic for a given network
area. We define a network area for which traffic need be optimized
using the ALTO service as an optimization area. Optimization area
definition is very important in ALTO service deployment, because
there are multiply types of network and topology infrastructure in
real Internet.
Traditional, an optimization area can be an access network, a MAN,
or a larger network consisting of both access works and MANs. An
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ISP with a relatively small network can define a single
optimization area and deploy an ALTO server for the area.
An ISP with a larger network may partition its network into
multiple optimization areas. Each optimization area may include
one or more MANs. Alternatively, the ISP may choose to use a large
optimization area and distribute a group of ALTO servers.
Besides the geographic point of view we can define the different
Optimization Areas through the type of network too. The networks
based on FTTx, ADSL,wifi and 3G or even 2G wireless technology has
different traffic model and infrastructure. ALTO service should
represent the difference between these networks.
2.2. Network and Cost Map Configuration
Key components for an ISP to configure when it deploys its ALTO
service are the Network Map and Cost Map. They have impacts on
both the load and the effectiveness of the service.
2.2.1. Network Map and PID
Different ISPs use different technologies to build their
infrastructures. Some ISPs have only a relatively small network,
focusing mainly on access. On the other hand, some large ISPs have
access networks, MANs, and a Core network. There are tradeoffs
when a large ISP defines its Network Map. If the partition of the
network in the Network Map is too fine-grained, it may lead to
higher complexity and overhead. On the other hand, a too coarse-
grained Network Map may lead to suboptimal optimization.
Specifically, first consider an access network, say an ADSL or
Ethernet based access network. A BAS server may be deployed to
provide access service for its subscribers. Because all
subscribers' traffic must be transmitted through the BAS server,
one technique is to identify each such access network by one PID.
It is generally unnecessary to further divide such access networks.
On the other hand, it can be beneficial to combine several such
access networks into a single PID.
A MAN usually consists of several access networks. The MANs are
connected to a core network, whose network bandwidth resource may
be costly for some networks. Thus, the ISP can define one or
several MANS as one PID. It is also possible that the ISP deploys
ALTO independently in some MANs.
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2.2.2. Cost Map
In ALTO protocol, cost map configuration can be used to tune the
traffic model. For example, to one optimization area of mobile
network, the wireless uplink is very limited in data transmission,
because of current mobile operators' configuration in 3G network.
So the cost to this optimization area can be higher, thus this area
can provide less traffic to other optimization areas.
In real ALTO service deployment, ISPs can plan its cost map
according to its optimization requirement and network conditions.
2.3. Endpoint Service Configuration
In ALTO protocol, Endpoint Property Service allows ALTO clients to
look up properties for individual endpoints. The endpoint cost
service allows an ALTO service to return either numerical costs or
ordinal costs (ranking) directly amongst Endpoints. Using these
services, ISP can provide more detail connectivity and cost
information of endpoint to upper application. For example in P2P
service, ISP can use this service to provide the connectivity type
of P2P clients to upper P2P operator.
Also in real deployment of ISP, different networks have different
connectivity characters, for example, ADSL network has asymmetrical
uplink and downlink bandwidth, as well as mobile network always
have small bandwidth compare to fixed network. Because all clients
access to Internet through ISPs, so ISPs have detail information of
each client's access character. Thus ISP can provide these
information to service operator.
In ALTO deployment of ISPs, there are some properties which are
necessary to the endpoint property service. P2P or CDN application
can benefit from that. We suggest to add the network type,
uplinkbandwidth and downlinkbandwidth into endpoint property
service .One example of these properties protocol usage is given
below.
POST /endpoint/prop/lookup?prop=pid HTTP/1.1
Host: alto.example.com:6671
Content-Length: [TODO]
{
"endpoints" : [ "192.0.2.34", "203.0.113.129" ]
}
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto
{
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"meta" : {
"version" : 1,
"status" : {
"code" : 1
}
},
"type" : "endpoint-property",
"data": {
"192.0.2.34" : { "pid": "PID1";
"networktype":"ADSL" ; " uplinkbandwidth ":"1M";" downlinkbandwidth
":" 4M"},
"203.0.113.129" : { "pid": "PID3";
"networktype":"GSM";" uplinkbandwidth ":"0M";" downlinkbandwidth ":"
64K"}
}
}
3. ALTO Deployment Monitoring
In addition to providing configuration, an ISP providing ALTO may
want to deploy a monitoring infrastructure to assess the benefits
of ALTO and adjust its ALTO configuration.
To construct an effective monitoring infrastructure, the ISP should
(1) define the performance metrics to be monitored; (2) and
identify and deploy devices to collect data to compute the
performance metrics. We discuss both below.
3.1. Monitoring Metrics
The monitoring of some performance metrics can be dependent on
specific applications, and ALTO can be applied to multiple
applications such as P2P and CDN. We focus on P2P applications.
3.1.1. Network Metrics
An ISP may monitor the impacts of ALTO on its network through a set
of performance metrics. We enumerate some key metrics. We define
the term domain as one or many groups of Endpoints. That is, one
domain includes one PID or some PIDs. Endpoints and PID are
defined in "draft-ietf-alto-protocol-05".
A specific set of metrics measuring the impacts of ALTO on networks
can include the following:
o Inter-domain ALTO-Integrated Application Traffic (Network
metric): This metric includes total cross domain traffic
generated by applications that utilize ALTO guidance. This
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metric evaluates the impacts of ALTO on the inbound and
outbound traffic of a domain.
o Total Inter-domain Traffic (Network metric): This is
similar to the preceding but focuses on all of the traffic,
ALTO aware or not. One possibility is that some of the
reduction of interdomain traffic by ALTO aware applications
may This metric is always used with the preceding and the
following metrics.
o Intra-domain ALTO-Integrated Application Traffic (Network
metric).
o Network hop count (Network metric): This metric provides
the average number of hops that traffic traverses inside a
domain. ALTO may reduce not only traffic volume but also the
hops. The metric can also indirectly reflect some
application performance (e.g., latency).
3.1.2. Application Metrics
Each specific application can have its specific set of performance
metrics. We give one example for file sharing.
o Application download rate (Application metric): This metric
measures application performance directly. Download means
inbound traffic to one user. Global average means the
average value of all users' download rates in one or more
domains.
o Application Client type audit(Application metric): this
metric gives the audit of client types in ALTO service. The
current types include fixed network client and mobile
network client.
3.2. Monitoring Data Sources
The preceding metrics are derived from data sources. We identify
four data sources.
3.2.1. Application Log Server
Many P2P applications deploy Log Servers to collect data.
3.2.2. P2P Clients
Some P2P applications may not have Log Servers. When available,
P2P client logs can provide data.
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3.2.3. OAM
Many ISPs deploy OAM systems to monitor IP layer traffic. An OAM
provides traffic monitoring of every network device in its
management area. It provides data such as link physical bandwidth
and traffic volumes.
3.3. Application/ISP Monitoring Integration
3.3.1. Structure
As discussed in the preceding section, some data sources are from
ISP while some others are from application. When there is a
collaboration agreement between the ISP and an application, there
can be an integrated monitoring system as shown in the figure
below. In particular, an application developer may deploy Monitor
Clients to communicate with Monitor Server of the ISP to transmit
raw data from the Log Server or P2P clients of the application to
the ISP.
+------------------------------------------------+
| |
| New Entities +--------------------------------------+
| | Service Provider |
| | (P2P/CDN Operator etc)|
| +-----------+ | +-----------+ | |
| |ALTO Server|-------------|ALTO Client| | |
| +-----------+ | +-----------+ | |
| | | +----------+ |
| | | |Log Server| |
| | | +----------+ |
| +--------------+ | +--------------+ | +----------+ |
| |Monitor Server|----------|Monitor Client| | |P2P Client| |
| +--------------+ | +--------------+ | +----------+ |
| | | | |
| +--------|--------+ +--------------------------------------+
+-|--------|--------|----------------------------+
| | |
| | |
| +---+ |
| |OAM| |
| +---+ |
| |
| ISP |
-----------------
Figure 1
3.3.2. ALTO Monitoring Report Protocol
A potential report message format from the Monitor Client to the
Monitor Server can be:
HTTP/1.1 200 OK
Content-Length: [TODO]
Content-Type: application/alto
{
"meta" : {
"version" : 1,
"status" : {
"code" : 1
}
},
"metric1 name" : "value",
"metric2 name" : "value",
}
4. IANA Considerations
This document makes no request of IANA.
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Note to RFC Editor: this section may be removed on publication as
an RFC.
5. Security Considerations
Multiple documents in the ALTO WG discuss security perspectives.
These documents complement this document.
6. References
6.1. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
6.2. Informative References
[2] H. Xie, Y.R. Yang, A. Krishnamurthy, Y. Liu, and
A.Silberschatz., "P4P:", In SIGCOMM 2008.
Appendix A. Acknowledgments
We thank the discussions with Kai Li.
Authors' Addresses
Xianghui Sun
China Telecom
Email: sunxh@ctbri.com.cn
Yang Richard Yang
Yale University
Email: yry@cs.yale.edu
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