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Building Blocks for IP Differentiated Services

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In the Transport Area, ADs Scott Bradner and Vern Paxson ... mark all traffic bound for 'frivolous' web sites for downgraded treatment. 9 ... – PowerPoint PPT presentation

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Title: Building Blocks for IP Differentiated Services


1
Update on the IETF Diffserv Working
Group NANOG 13 Detroit, MI June 8, 1998
Kathleen M. Nichols knichols_at_baynetworks.com
2
Overview
  • Working Group information
  • Diffserv overview
  • What were doing
  • What were not doing
  • Where were at
  • Interim meeting, June 11 and 12

3
Diffserv Working Group
  • In the Transport Area, ADs Scott Bradner and Vern
    Paxson
  • Chartered in February, co-chairs Brian Carpenter
    of IBM and myself
  • General Discussiondiff-serv_at_baynetworks.com
  • Related topicsdiff-serv-interest_at_baynetworks.com
  • To Subscribe majordomo_at_baynetworks.com
  • In Body subscribe diff-serv (or
    diff-serv-interest)
  • Archive http//www-nrg.ee.lbl.gov/diff-serv-arch/
  • IETF page www.ietf.org/html.charters/diffserv-cha
    rter.html

4
Goals and Milestones
  • Apr 98 Meet at LA IETF to review strawman spec
  • June 98 Interim meeting in Boston, MA (6/11-12)
    to review revised spec, architecture, framework
    docs
  • Jul 98 Submit drafts to IESG for consideration
    as RFCs (expect spec and architecture doc)
  • Aug 98 Meet at Chicago IETF to discuss boundary
    mechanisms and traffic conditioners
  • Oct 98 Publish drafts on boundary mechanisms and
    traffic conditioners
  • Dec 98 Meet at IETF to finalize boundary
    mechanisms and traffic conditioners documents

5
What is Diffserv?
  • Use minimal standardization to provide tools and
    knobs that
  • Allow traffic engineering within your domain
  • Allow you to offer new services to customers
  • Uses a bit-field in the packet (6 bits of the
    IPv4 TOS or IPv6 Traffic Class octet) as a
    codepoint to determine the packets forwarding
    treatment

6
Diffserv codepoint and PHB model
  • Codepoints should be looked at as an index into a
    table of packet forwarding treatments at each
    router (PHBs)
  • Behavior for a few codepoints will be globally
    assigned (e.g., precedence 6/7 routing traffic)
    but most codepoints are left for your use
  • Vendors providing diffserv-capable equipment must
    make codepoint to behavior mapping flexible and
    accessible to you

7
How does Diffserv work?
  • A packet may be marked with a codepoint
    anywhere in the network (but marking probably
    occurs at domain boundaries)
  • All packets with the same codepoint get the same
    behavior (providing aggregation and scalability)
  • Per-flow state stays at network edges
  • Marking can be based on microflow identification,
    the packet ingress link, the measured temporal
    characteristics of a microflow or aggregate, etc.
    (Diffserv-capable equipment will include traffic
    conditioners you can configure.)

8
Examples of traffic engineering with diffserv
  • Use codepoints to
  • map packets to weighted round-robin queues
  • one might get majority share of the output link
    during congestion
  • one might get no share unless there is no other
    traffic
  • invoke drop preference mechanisms to give
    preferential treatment to some packets during
    congestion
  • mark all traffic bound for frivolous web sites
    for downgraded treatment

9
New Customer Services from Diffserv
  • Services built by adding rules to behaviors
  • Rules for initial packet marking
  • Rules for how particular aggregates are treated
    at boundaries
  • Rules for temporal behavior of aggregates at
    boundaries
  • Only requires bilateral agreement at domain
    boundaries (i.e., no end-to-end agreements
    required)

10
What were doing
  • Specify the fowarding path while letting the
    policy mechanisms evolve
  • analogy to IP forwarding/routing
  • this allows a wide range of uses of the basic
    building blocks
  • Standards track for DS field and a small base set
    of PHBs (with limited RFC791 backward
    compatibility)
  • Informational track for architecture doc,
    specifications of traffic conditioners

11
What were not doing
  • Specifying policy mechanisms and protocols
  • Service specifications
  • Specifying specific implementations of PHBs
  • Standardizing the entire code space of the DS
    field
  • Telling you how to use the building blocks

12
Where were at now
  • Five WG drafts
  • a strawman spec (dsopdefs - out of date)
  • revised spec (header-00 - soon to be new
    version)
  • backwards compatibility spec (precedence - to
    be split)
  • architecture doc
  • framework doc
  • RSVP interoperability informational doc (in pipe)
  • Next version of the spec (header-01) will come
    out after the Interim meeting and should include
    some codepoints from the precedence draft

13
Partial Issue List for the Interim Meeting
  • Allocation of experimental and local use
    codepoints, migration to standard values
  • Number and type of PHBs to be allocated specific
    codepoints in base set
  • Handling backward compatibility (RFC791)
  • Mechanisms to deliver assured service
  • Review of Architectural and Framework documents

14
Some Topics for the Interim Meeting
  • Proposal for EXP registration/migration
  • Discussion of first standards track document
    (draft-ietf-diffserv-header-00,portions of
    draft-ietf-diffserv-precedence)
  • Assured service (portions of draft-ietf-diffserv-p
    recedence)
  • Architecture and Framework documents to be
    discussed (draft-ietf-diffserv-arch and
    draft-ietf-diffserv-framework)

15
Summary
  • Diffserv is useful for both end-to-end service
    and intra-domain traffic control
  • The diffserv WG is concentrating on standards
    track RFCs and informational RFCs that concern
    the diffserv building blocks that appear in the
    packet forwarding path, not policy issues
  • The WG schedule is aggressive and, so far, is
    being met
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