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Use Cases for Power-Aware Networks
draft-zhang-panet-use-cases-00

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This is an older version of an Internet-Draft whose latest revision state is "Expired".
Authors Mingui Zhang , Jie Dong , Beichuan Zhang
Last updated 2012-10-15
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draft-zhang-panet-use-cases-00
INTERNET-DRAFT                                              Mingui Zhang
Intended Status: Proposed Standard                              Jie Dong
Expires: April 18, 2013                                           Huawei
                                                          Beichuan Zhang
                                               The University of Arizona
                                                        October 15, 2012

                                    
                  Use Cases for Power-Aware Networks 
                   draft-zhang-panet-use-cases-00.txt

Abstract

   Power Aware NETwork (PANET) has attracted strong interest from both
   carriers and vendors. Several use cases are investigated in this
   document to exhibit the potential usage of PANET in both backbone and
   data center networks.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
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   The list of current Internet-Drafts can be accessed at
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Copyright and License 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
   (http://trustee.ietf.org/license-info) in effect on the date of
 

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   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   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
     1.1. Conventions used in this document . . . . . . . . . . . . .  3
     1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Power Awareness in Backbone Networks  . . . . . . . . . . . . .  3
     2.1. Use Case 1: Sleeping Links  . . . . . . . . . . . . . . . .  4
     2.2. Use Case 2: Composite Links . . . . . . . . . . . . . . . .  5
   3. Power Aware in Data Center Networks . . . . . . . . . . . . . .  5
     3.1. Server Consolidation  . . . . . . . . . . . . . . . . . . .  6
     3.2. Power Aware Load Balancing Among Multiple Sites . . . . . .  6
     3.3. Elastic Network Infrastructure  . . . . . . . . . . . . . .  7
   6. Security Considerations . . . . . . . . . . . . . . . . . . . .  7
   7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  7
   8. References  . . . . . . . . . . . . . . . . . . . . . . . . . .  7
     8.1. Normative References  . . . . . . . . . . . . . . . . . . .  8
     8.2. Informative References  . . . . . . . . . . . . . . . . . .  8
   Author's Addresses . . . . . . . . . . . . . . . . . . . . . . . .  9

 

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1. Introduction

   Networks are usually provisioned for peak hours and potential network
   failures and network devices are powered on all the time without
   consideration on energy efficient. In practice, however, the traffic
   load of a network is low most of the time and redundant network
   equipments are used for failure recovery occasionally.

   In the past years, vendors had paid a great effort on improving the
   network energy efficiency at the device level: when the traffic load
   is low, a network equipment should accordingly operate with less
   power draw. However, network equipments have never become fully power
   proportional. Even few or no traffic is carried, a powered-on network
   device draws a considerable amount of power, which means energy is
   being wasted. There is an explicit gap for idle network devices to be
   shut down or put into sleeping state to save more energy. In order to
   fill this gap, the network control plane and management system should
   become power aware to coordinate network devices therefore the
   sleeping or off network devices do not bring disruption to the
   network.

   This documents investigated several use cases on power aware network
   which include both backbone networks and data center networks. As for
   the energy efficiency of backbone networks, only intra-domain use
   cases are considered. Trying to be energy efficient in the inter-
   domain scale seems technically feasible, for now though, energy
   efficient solutions can easily end up lack of business motivation,
   this document leaves them for future study. 

1.1. Conventions used in this document

   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].

1.2. Terminology

   PANET: Power Aware NETwork

2. Power Awareness in Backbone Networks

   The IETF Energy Management (eman) Working Group works on the
   management of power-aware network devices. Basically, the power
   states of power-aware network devices are reported and recorded in
   MIB. However, there is a gap on how to make use of this kind of data
   to achieve energy efficient networks. With energy aware control plane
   [power-control], it becomes possible to make use of these
   measurements and power control ability to achieve the energy
 

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   efficiency of a whole network.

   This section lists several use cases for backbone networks. Take a
   router system as an example, the start-up of it may take several
   minutes and the stabilization of it may takes much longer time. It is
   unrealistic to switch off and on a whole node in backbone networks
   frequently to achieve energy efficient, so this document only
   investigates the cases in which links (i.e., links' attached
   components) are shut-down for energy conservation.

2.1. Use Case 1: Sleeping Links 

              +----------------+        +----------------+
              |Router          |        |          Router|
              |                |        |                |
              |                |        |                |
              |      +---------+        +---------+      |
              |      |Line-card|        |Line-card|      |
              |      |         |        |         |      |
              |      |     +---+  Link  +---+     |      |
              |      |     |NPU+--------+NPU|     |      |
              +------+-----+---+        +---+-----+------+

                   Figure 2.1: Power Aware Line-cards

   The power draw on line-cards occupies a great portion in the total
   power consumption of a whole routing system. For high-end routers,
   this portion may be higher than 50%.

   Network devices and their processing capacity are provisioned for
   worst cases such as traffic burst and busy hours. Most of the time,
   the network is lightly loaded. Unfortunately, the power consumption
   of network devices is not proportional to the traffic load on them.
   Even there is no load on them, there is still a considerable base
   power consumption. Unlike personal PCs which can be shut down or
   enter power saving modes (such as sleeping), network devices are
   powered on and running even they are idle. This reality means that
   the network is wasting powers.

   The conception that "a link is put into sleep state" is frequently
   mentioned. In this document, this conception is formalized as
   follows. The coupled end-points (such as interfaces, NPU or whole
   line-cards) attached to a idle link (as shown in Figure 2.1) enter
   the sleeping mode to save energy. 

   Traffic aggregation are used to create the opportunity for more links
   to become idle. This process can be automated through the control
   plane, such as Traffic Engineering [GreenTE].
 

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   The essentials of this use case:

   o  Devices to be Power Aware: Routers and their line-cards.

   o  What actions to take: NMS measures the traffic load and power
      profile each link [eman]; Routers execute the green TE algorithm;
      Routers send out signals to trigger the power-on/power-off of a
      NPU on a line card. 

2.2. Use Case 2: Composite Links

   A composite link is logical link composed of multiple physical [I-
   D.ietf-rtgwg-cl-requirement]. The composite link attached end-points
   are responsible to map traffic onto the component links and maintain
   the state of the composite link. Power awareness can be applied to
   composite links as well. When the traffic volume on the composite
   link is low, some component links can be shut down to conserve energy
   consumption. When the traffic volume becomes high, the sleeping
   members links can be waken up to absorb the traffic load. 

   Compared to use case 1, the advantage of executing energy saving for
   composite link is that the connectivity of the composite link does
   not suffer unless all the component links are cut off. In this way,
   the control plane of the component link is not disrupted. In other
   words, when the end points of the composite link execute the energy
   conservation action, they can do it in a distributed way and
   decisions are made locally.

   The essentials of this use case:

   o  Devices to be Power Aware: Composite links attached end-points.

   o  What actions to take: NMS measures the traffic load and power
      profile of component links; Attached end-points adaptively turn-
      on/turn-off component links according to the traffic load on the
      composite link. 

   Use case 1 and use case 2 may be combined in a real network to
   achieve more energy saving.

3. Power Aware in Data Center Networks

   Servers, network devices (ICT equipments) are intensively placed in
   Data Centers. In comparison with ISP backbone networks, the operating
   of Data Center Networks are more power hungry. The growing amount of
   energy consumed by a Data Center has led to high operating costs. 

   Although non-ICT equipments, such as lighting and air conditioners,
 

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   in a Data Center consumes a notable large amount of energy as well,
   this section concentrate on talking about right sizing ICT equipments
   for energy conservation. Energy conservation of non-ICT equipments
   are out of the scope of this document.

3.1. Server Consolidation 

   With virtualization technology, Virtual Machines (VMs) can be
   consolidated to fewer physical servers while idled servers can be put
   into power saving mode or turned off to achieve energy conservation
   of the whole Data Center. Virtualization technology allows the
   administration of a Data Center Network respond rapidly to the
   fluctuating capacity requirements.

   Through monitoring of the work load and power profile, the Data
   Center Network Management System (Orchestrator) can judge in which
   hours workload is high and in which hours workload is low. For
   example, nights are generally off-peak hours in which workload is at
   low level. Virtual machines can be moved to fewer servers therefore
   idle servers can powered off or put into sleep to save energy. Before
   peak hours (e.g., in the morning), sleeping or powered off servers
   should be waken up to accommodate more active virtual machines
   (VMs).

   The essentials of this use case:

   o  Devices to be Power Aware: All servers in a data center.

   o  What actions to take: NMS measures the work load and power profile
      of servers; The orchestrator of a Data Center Network adaptively
      triggers the actions of VM migration, the power-off and power-on
      of servers according to the workload.

3.2. Power Aware Load Balancing Among Multiple Sites

   An enterprise may have multiple data centers which spread out in
   different geographic locations. Generally, the ICT resources in these
   data centers are well replicated and a job can be directed to any of
   them for execution. These data centers form a large distributed
   Internet scale systems and the price of power supply for them varies
   between two different locations. The operating cost of such a system
   highly depends on the load balancing scheme. Being power aware, the
   system can map requests to locations where energy price is cheaper.  

   This use case makes use of the difference of the prices of power draw
   in different locations. The orchestration of data centers (the NMS)
   is responsible for monitoring the power profile and work load of the
   ICT devices located in different data centers. 
 

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   The essentials of this use case:

   o  Devices to be Power Aware: All ICT-equipments in a data center.

   o  What actions to take: ICT devices report their work load and power
      consumption profile to NMS. The orchestration (NMS) of the Data
      Center Networks adaptively map the request onto sites in
      consideration of reducing the overall power bill of the system.

3.3. Elastic Network Infrastructure

   Traffic load of a data center is generated by the work load on
   servers and applied on the network infrastructure. The changing work
   load determines that the traffic load varies as time goes on.
   However, network devices are always left on even though the traffic
   load fluctuates, which wastes energy inevitably when the traffic load
   is low. 

   Ideally, the network infrastructure is elastic and can fit the
   traffic pattern with minimum subset to minimize the energy
   consumption of the network infrastructure. For now, Data Center
   Networks generally work at layer 2. So this use case should be
   realized through manipulating switching paths, in comparison with the
   power aware routing at layer 3. Openflow switches of SDN may be
   utilized to achieve this goal [ElasticTree]. 

   The essentials of this use case:

   o  Devices to be Power Aware: All network equipments in a data
      center.

   o  What actions to take: Network devices report their traffic load
      and power consumption profile to NMS. The orchestrator (NMS) of a
      Data Center Network adaptively build the switching paths upon the
      network infrastructure. The idled links are put into power saving
      mode (e.g., sleeping), so that the network infrastructure becomes
      energy efficient.

6. Security Considerations

   This document raises no new security issues.

7. IANA Considerations

   No new registry is requested to be assigned by IANA. RFC Editor:
   please remove this section before publication.

8. References 
 

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8.1. Normative References

   [power-control] A. Retana, R. White,  M. Paul, "A Framework and
             Requirements for Energy Aware Control Planes", draft-
             retana-rtgwg-eacp-00.txt, work in progress.

   [eman] IETF, "Energy Management Working Group Charter", 2012,
             <http://datatracker.ietf.org/wg/eman/charter/>.

   [I-D.ietf-rtgwg-cl-requirement] Villamizar, C., McDysan, D., Ning,
             S., Malis, A., and L. Yong, "Requirements for MPLS Over a
             Composite Link", draft-ietf-rtgwg-cl-requirement-07 (work
             in progress), June 2012.

8.2. Informative References

   [GreenTE] Zhang, M. and et al. , "GreenTE: Power-Aware Traffic
             Engineering", ICNP 2010.

   [Rate-Adaptation] S. Nedevschi, L. Popa, G. Iannaccone, S. Ratnasamy,
             and D. Wetherall, "Reducing Network Energy Consumption via
             Sleeping and Rate-Adaptation," in Proceedings of USENIX
             NSDI, 2008.

   [ElasticTree] B. Heller, S. Seetharaman, P. Mahadevan, Y. Yiakoumis,
             P. Sharma, S. Banerjee, and N. McKeown, "ElasticTree:
             Saving Energy in Data Center Networks," in Proceedings of
             USENIX NSDI, 2010.

 

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Author's Addresses

   Mingui Zhang
   Huawei Technologies Co.,Ltd
   Huawei Building, No.156 Beiqing Rd.
   Beijing 100095 P.R. China
        
   Email: zhangmingui@huawei.com

   Jie Dong
   Huawei Technologies Co.,Ltd
   Huawei Building, No.156 Beiqing Rd.
   Beijing 100095 P.R. China
        
   Email: jie.dong@huawei.com

   Beichuan Zhang
   The University of Arizona

   Email: bzhang@cs.arizona.edu

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