Internet DRAFT - draft-chen-trill-te-applicability

draft-chen-trill-te-applicability







Network Working Group                                            G. Chen
Internet-Draft                                                     C. Li
Intended status: Informational                              China Mobile
Expires: January 16, 2014                                  July 15, 2013


      The Applicability Analysis of Traffic Engineering over Trill
                  draft-chen-trill-te-applicability-00

Abstract

   This memo intended to describe the needs of Traffic Engineering (TE)
   in a Data Center Network (DCN) in which Transparent Interconnection
   of Lots of Links (Trill) has been adopted.  Several use cases have
   been proposed to demonstrate the usage while the feasibility of Trill
   extension has been evaluated.  It serves to motivate the normative
   work subsequently.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on January 16, 2014.

Copyright Notice

   Copyright (c) 2013 IETF Trust and the persons identified as the
   document authors.  All rights reserved.












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   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Motivations . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
     3.1.  Bandwidth Ensuring  . . . . . . . . . . . . . . . . . . .   3
     3.2.  Link Protections  . . . . . . . . . . . . . . . . . . . .   4
     3.3.  Traffic Matrix  . . . . . . . . . . . . . . . . . . . . .   4
     3.4.  Unequal Load Balancing  . . . . . . . . . . . . . . . . .   5
   4.  Applicabilty Analysis . . . . . . . . . . . . . . . . . . . .   5
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   7.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Transparent Interconnection of Lots of Links (Trill) protocol is
   targeted to improve link utilizations of switch networks.  With the
   growth of Data Center Network (DCN), this technology is widely used
   and approved to be an essential component building layer-two
   networks.  The services in DCN could benefit from multi-path
   forwarding for good flexibility and resilience.  Shortest Path First
   (SPF) is used to forward data frames.  The selection of forwarding
   path is inherited from a routing protocol, which may be optimized
   based on a simple additive metric.  Those algorithms are generally
   topology-driven, so link utilizations and traffic features can't be
   factors considered in data path decisions.

   Traffic Engineering (TE) provided a useful feature to improve
   the performance of the telecommunication networks.  The ultimate
   objective is to avoid congestion in the network by keeping its links
   from being overloaded.  Current uses are exclusively focused on the
   applications of Multiprotocol Label Switching (MPLS).  It's normally
   deployed in a large Internet backbone.  The adoption in a DCN
   environment is worth to be investigated given the scale of large
   Ethernet networks has been dramatically expanded.




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   This document describes service characteristics in a DCN.  The
   deployment of traffic engineering would likely optimize the Quality
   of Experiences.  It motivates the work to populate TE functions into
   Trill protocol.  Several use cases help to elaborate the usages of
   those technologies.  The considerations of technical principle can
   also be deduced from actual uses.  This memo also provided the
   possibilities of protocol design.

2.  Motivations

   Data centers are being heavily employed in enterprise and consumer
   settings to run a variety of applications and cloud-based services.
   These range from Internet-facing "sensitive" applications, such as,
   Web services, instant messaging, stock updates, financial
   applications and gaming, to storage intensive applications, such as,
   data analysis, file sharing and scientific computing.  The
   performance of these applications crucially depends on the
   functioning of the data center's network infrastructure.  For
   example, a congested data center network, where internal traffic is
   routinely subjected to losses and poor throughput, could lead search
   queries to take longer to complete, instant message to get delayed,
   gaming experience to deteriorate, and POP mail services and Web
   transactions to hang.  The dissatisfied end-users and subscribers
   could choose alternate providers, resulting in a significant loss in
   revenues for the data center.  TE mechanism likely could help the
   situation by monitoring the link's loads and traffic growth trends.
   It's desirable to introduce the technology into DCN even there is
   constituted with a number of switch device.

   Trill has been adopted in DCN in recent years.  SPF-based algorithm
   still can't provide satisfactory performance if congestions are
   occurred on the links.  Our preliminary study reveals that SPF-based
   algorithm achieve only 80-85% of the performance achieved by an
   optimal TE algorithm.  It indicates that there is significant room
   for improvement if TE functions could be integrated with Trill.
   Those benefits could motivate new works on Trill-TE.

3.  Use Cases

3.1.  Bandwidth Ensuring

   The Fig. 1 shown the case, in which different services, including
   gaming, stroge backup and web browse are relied on a switch network.
   There are two paths between ingress RB1 and egress RB3, i.e. RB1---
   RB2---RB3 and RB1---RB4---RB5--RB6.  Trill-TE is used to guarantee
   the performance of gaming with low delay.  And other services would
   bypass the route gaming traversed so as to avoid congestions with
   gaming.  Therefore, RB1---RB2---RB3 are served as to transmit the



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   gaming data.  RB1---RB4---RB5--RB6 has been selected for other data
   services.

            +-----+       +-----+        +-----+
            | RB4 |-------| RB5 |--------| RB6 |
            +-----+       +-----+        +-----+
               |                            |
            +-----+       +-----+        +-----+
            | RB1 |-------| RB2 |--------| RB3 |
            +-----+       +-----+        +-----+
       Ingress |                            | Egress

   Figure 1: Bandwidth Ensuring with Trill-TE


3.2.  Link Protections

   The Fig.2 shows the topology.  Ingress RB1 would go through the way
   of RB1-- RB2--RB3--RB4 to RB8.  If there is failure detected on the
   path.  Trill-TE would switch the traffic to the backup link, i.e.
   RB1-- RB5--RB6--RB7--RB8.  Once the above link is recovered, the
   traffic would be switched back to below link.

              +-----+       +-----+        +-----+
      +------ | RB2 |-------| RB3 |--------| RB4 |-------+
      |       +-----+       +-----+        +-----+       |
   +-----+                                            +-----+
   | RB1 |Ingress                                     | RB8 |Egress
   +-----+                                            +-----+
      |       +-----+       +-----+        +-----+       |
      +------ | RB5 |-------| RB6 |--------| RB7 |-------+
              +-----+       +-----+        +-----+

   Figure 2: Link Protections with Trill-TE


3.3.  Traffic Matrix

   Various traffic flows can be well gauged when the Trill is capable of
   Traffic Engineering.  Operators could get accurate traffic statistics
   because the traffic is deterministically transmitted over the planned
   data paths.  The deployment of traffic engineering in a DCN helps to
   form a traffic matrix, which provides the volume of traffic between
   every pair of ingress and egress points over a given time interval.
   Such information is critical inputs to network design, capacity
   planning and business planning.





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3.4.  Unequal Load Balancing

   Unequal load balancing could help to utilize bandwidth resource
   properly.  Each link is vary in the exchange capability, for example
   10GbE, 40GbE or 100GbE have been deployed on the route paths.  The
   traffic engineering in Trill could distribute the flow on the matched
   link.  It could optimize the network resource uses as a whole.

4.  Applicabilty Analysis

   The following is the features Trill-TE could leverage.  Those can
   verify the feasibility of this work.

   o  Multipath: Trill-TE must take advantage of the path diversity
      available in the data center's network.  Based on that, the
      forwarding path can be decided via an global view of traffic.

   o  Metric transmission: IS-IS Extensions for Traffic Engineering is
      already defined in [RFC5305].  Trill-TE may need to insert
      Nicknames to the forwarding table for the TE routing path.  The
      existing Trill process would immune to those changes.

5.  IANA Considerations

   This document makes no request of IANA.

6.  Security Considerations

   TBD

7.  Normative References

   [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
              Engineering", RFC 5305, October 2008.

Authors' Addresses

   Gang Chen
   China Mobile
   53A,Xibianmennei Ave.,
   Xuanwu District,
   Beijing  100053
   China

   Email: phdgang@gmail.com






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   Chen Li
   China Mobile
   53A,Xibianmennei Ave.,
   Xuanwu District,
   Beijing  100053
   China

   Email: lichen@chinamobile.com











































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