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Versions: 01

ALTO                                                             H. Song
Internet-Draft                                                    Y. Lee
Intended status: Informational                                    Huawei
Expires: August 26, 2013                                    Feb 22, 2013


           Infrastructure to Application Information Exposure
                        draft-song-alto-i2rs-01

Abstract

   This document describes the scenarios that applications can use the
   network layer especially the network routing system exposed
   information, so as to optimize application layer traffic.  The use
   cases in this document include the ISP broadband network (using P2P
   and CDN as examples) and the data center network.  This document
   also describes what information should be collected for
   ALTO service for traffic optimization.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on August 26, 2013.

Copyright Notice

   Copyright (c) 2013 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
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   to this document.  Code Components extracted from this document must



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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
     3.1.  ISP network . . . . . . . . . . . . . . . . . . . . . . . . 3
     3.2.  Data Center Network . . . . . . . . . . . . . . . . . . . . 4
   4.  Open Discussion . . . . . . . . . . . . . . . . . . . . . . . . 6
   5.  Informative References  . . . . . . . . . . . . . . . . . . . . 6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . . . 7




































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1.  Introduction

   ALTO provides an interface to applications and appropriate
   information to guide an optimal node selection when there are more
   than one application node providing the same service, through
   aggregated network map and cost map. It usually aggregates network
   locations into PIDs, and assigns lower cost value for a PID pair that
   are topologically closer. So when application node follows the advice
   from ALTO server to choose one resource provider within a PID that
   has lower cost from its own PID, with higher probability the
   application node can keep the content request and response traffic
   flow intra domain. This can reduce interdomain traffic for ISPs, and
   avoid the congestion in the backbone network.  More factors for node
   selection can be considered, such as pricing, congestion, and etc.

   In order to assure optimality, the underlying infrastructure needs
   to expose its topology information, node/link status information,
   pricing information for path selection to ALTO server, which will
   either be abstracted as the network map or as the impacting input
   factor of cost map.


2.  Terminology

   I2AEX: Infrastructure to Application Exposure.

   ALTO: application layer traffic optimization.

   IaaS: Infrastructure as a Service.


3.  Use Cases

3.1.  ISP network

   ISP broadband networks are consisted of interconnected autonomous
   systems.  They run BGP protocols between the boarder gateway routers,
   and run IGP protocols intra autonomous systems.  There are core
   routers, and access routers (BRAS) which fullfill the admission
   control through RADIUS servers, the access router connects to
   multiple aggregation switches.  And an aggregation switch connects to
   multiple DSLAMs or OLTs.  And the DSLAM or OLT connect to the home
   gateways or ONUs, which connect to the user devices.  [It's better to
   give a figure here.]

   The ISP network usually hide all its information to applications.
   But in the trend of big traffic use case, the main motivation is to
   reduce the backbone and interdomain traffic.  CDN and P2P are the two



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   target applications.  In a P2P application, the content requester
   requests contents from peers in the same swarm.  It may choose a peer
   that is far way ignoring a peer that is topologically closer to it.
   Due to the topology ignorance, the application may creates
   unnecessary backbone and interdomain traffic.

   In another application of CDN, a popular resource usually is stored
   in multiple data centers.  Without the knowledge of the network
   topology, the CDN's DNS server can redirects the content requester to
   a sub-optimal edge server, which is not always topolocially close to
   the content requester.  Even with measuring the round trip time
   between its edge servers and the requester's local DNS server, it may
   not get the accurate result because RTT is dynamic and user can
   specify its own DNS server.

   For the above two broadband network use cases, the infrastructure
   information from the home to the access router does not help much.
   But more attendtion should be paid to the information from the access
   router to the routing system, which can provide important input for
   the ALTO maps.  An ALTO server needs the following information as
   input:

   o The network segments information.  Every access router manages one
   or more IP address pools, to be assigned to the users through DHCP or
   other ways.

   o The IP addresses of the interfaces of routers, and the routing
   table information(IGP or BGP).  This information can help to
   construct the whole network topology.

   o The congestion status of the router interfaces, but this
   information could be reflected in the routing table change.

   o Policy information. For example, one multi-homing AS prefers to
   use which AS to transit its traffic, including the pricing
   information.

   ALTO can use the collected information mentioned above to be able to
   select a node topologically closer, with lower transit price and
   less congested link.

3.2.  Data Center Network

   Infrastructure as a service (IaaS) is a way how the data center
   provides its services.  There are different kinds of resources in a
   data center, physical machines, virtual machines, switches,
   firewalls, computing power, storage space, and electric power.
   [I-D.lee-alto-ext-dc-resource] proposes collecting data
   center resource information to make use of such information for a key


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   decision to allocate the application request to an "optimal" Data
   Center location in which to host the application request.  Key
   constraints in this decision include resource availability (e.g.,
   memory, storage, CPU, etc.), DC network cost, DC network resource
   constraints (e.g., bandwidth), structure constraints (e.g., Data
   Center power consumption) and others.

   Combined computing and network resource optimization is of value to
   both application owners and data center operators.  For example a
   data center operator with multiple buildings in a metropolitan area
   may also want to balance compute and network costs.

                               +--------------+
             Resource Request  | Application  |
                  -----------> | Orchestrator |
                               +-------+------+
                                       |
      +--------+                  +----+----+                 +--------+
      |        |                  |         |                 |        |
      |  DC 1  |<--------+------->|  ALTO   |<-------+------->|  DC 2  |
      |        |   ALTO-interface | Client  |  ALTO-interface |        |
      +--------+                  +---------+                 +--------+
                                      /|\
                                       |
                                       + ALTO-interface
                                       |
                                      \|/
                                  +---------+
                                  |         |
                                  |  DC 3   |
                                  |         |
                                  +---------+

   The ALTO server needs to collect the following information so as to
   provide this kind of service.

   o All switches' network capacity information

   o All physical servers' information(CPU, memory) in the data center

   o The storage space information in the data center

   o The physical links information

   o The virtual machines' information(CPU, memory) and its affinity

   o Pricing models




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   Based on the aforementioned information, ALTO server can provide the
   load balancing/traffic optimization information to ALTO client for
   data centers, through map or ranking.


4.  Open Discussion

   In order to optimize the application traffic, network layer needs to
   provide necessary information to the according applications in the
   previous section, with a method (request/response, or subscription/
   notification) to make the underlying information changes be timely
   sent to the ALTO server.  This requires more interactions between the
   network layer and the application layer.  I2RS seems to consider more
   configuration use cases such like policy based routing, but what ALTO
   protocol needs is the part that discloses the network information.
   So there could be two ways to go forward.

   (1) Defining a new protocol to cover all required functions such as
   configuration and information disclosure required by I2RS.  This
   protocol covers ALTO's south bound information requirements on network
   topology, with its one component.  But this protocol will be
   tremendously complicated.  It will be related and overlapped with
   other existing protocols, such like NetConf and YANG.

   (2) Defining the south bound interface for ALTO, to collect the
   infrastructure information, and bring the requirements discussion in
   I2RS, and identify the final scope, to avoid the overlap between
   different WGs(ALTO, NetConf, NetMod).  In this case, the protocol
   development will belong to ALTO WG.


5.  Informative References

   [I-D.lee-alto-ext-dc-resource]
              Lee, Y., Bernstein, G., and D. Dhody, "ALTO Extensions for
              Collecting Data Center Resource Information",
              draft-lee-alto-ext-dc-resource-01 (work in progress),
              January 2013.

   [I-D.ietf-alto-protocol]
              Alimi, R., Penno, R., and Y. Yang, "ALTO Protocol",
              draft-ietf-alto-protocol-13 (work in progress),
              September 2012.

   [RFC5693]  Seedorf, J. and E. Burger, "Application-Layer Traffic
              Optimization (ALTO) Problem Statement", RFC 5693,
              October 2009.




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Authors' Addresses

   Haibin Song
   Huawei

   Email: haibin.song@huawei.com


   Young Lee
   Huawei

   Email: leeyoung@huawei.com







































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