Diff-Serv-aware Traffic Engineering draft-ietf-mpls-diff-te-reqts-00.txt

1
Diff-Serv-aware Traffic Engineering
draft-ietf-mpls-diff-te-reqts-00.txt

• IETF TE WG,
• Dec 2000, San Diego

Francois Le Faucheur, Cisco Systems Angela Chiu,
ATT William Townsend, Tenor Networks Darek
Skalecki, Nortel Tom Nadeau, Cisco Systems Martin
Tatham, BT
2
History
Pittsburgh
San Diego
draft-lefaucheur-diff-te-reqts-00.txt draft-lefa
ucheur-diff-te-ext-00.txt
draft-ietf-mpls-diff-te-reqts-00.txt draft-ietf-
mpls-diff-te-ext-00.txt draft-lefaucheur-diff-te-
ospf-00.txt draft-lefaucheur-diff-te-isis-00.txt
made MPLS WG document
3
Motivation

• Current MPLS TE
• can be used simultaneously with Diff-Serv
• performs constraint based routing (CBR) on a
  single BW constraint
• this is sufficient for many environments

4
Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  linkeg
• link speed 155 Mb/s
• Max Reservable Bandwidth Aggregate 155
• Max Reservable Bandwidth for EF/Voice 70

5
Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
On link B--gtD 40 30 lt 70 40 30 40 lt 155
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Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of Voice?
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Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of Voice? No, because 40 30 10 gt 70
8
Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of Voice? No, because 40 30 10 gt 70
9
Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of BE Data?
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Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of BE Data? Yes, because 403040 10 lt
155
11
Motivation

• Good EF behavior requires that aggregate EF
  traffic is less than reasonable of link (for
  instance 50)
• BE behavior fine if aggregate traffic is 100 of
  link

B
Voice 40
Voice 30
155
155
BE Data 10
BE Data 40
155
A
D
155
C
Can I use Link B-gtD to set up a new LSP A--gtD for
10 Mb/s of BE Data? Yes, because 403040 10 lt
155
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Motivation

• CBR needs to include the link for BE and exclude
  the link for Voice/EF
• current TE, IGP advertises single unreserved Bw
  value for all CoS gt a link is either included
  or excluded by CBR for all CoSs
• IGP needs to advertise a different unreserved
  Bw for BE and for Voice
• RSVP-TE/ CR-LDP need to signal CT so that CAC is
  performed depending on CT

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Motivation

• Only applies to some environments
• Distributed Route Computation
• Voice traffic is significant compared to link
  speed
• distribution of traffic across Classes is not
  consistent everywhere
• Examples
• global ISPs (e.g., Concert), especially on
  transoceanic links
• telco transporting very large Voice Trunks (e.g.
  ATT)

14
Motivation

• Pre-standard implementations available today
• tests/experimentation carried out by SPs(SPs to
  present at next IETF?)
• need for a standard to allow future
  interoperability

15
Principles

• Class-Type (CT) arbitrary set of DS Classes with
  same Bw constraints
• eg. CT0BE, CT1AF1AF2, CT2EF
• Configurable Max Reservable per CT
• eg Max CT0155, Max CT1120, Max CT275
• IGP advertise Unreserved Bw per CT
• CBR uses advertised Unrsvd Bw of relevant CT
• RSVP-TE/CR-LDP signal CT

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Issue

• How many CTs should we allow?
• proposal
• 2 is the burning requirement
• 4 is comfortable
• remember one CT can comprise multiple classes
• Examples
• SP1 only uses existing TE (single CT)
• SP2 uses 2 CTs (Data,Voice)
• SP3 uses 3 CTs (Voice, Low Loss data, BE)

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Issue

• How does preemption play within and across CTs?
• Proposal
• do not constrain how many, and which, preemption
  levels are used by each CT
• preemption operate independently of CTLSP1(P1)
  will preempt LSP2(P2) if P1ltP2 regardless of
  LSP1s CT and LSP2s CT
• Examples
• SP1 uses P0 for Voice, P1 for Data
• SP2 uses P0P1 for Voice, P2P3P4 for Data

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Issue

• How to minimise IGP scalability impact?
• Proposal
• no configuration required regarding which
  preemption level is used by which CT
• IGP will not advertise Unrevd Bw for preemption
  levels which are not used()
• Examples
• SP1 uses P0 for Voice, P1 for Data
• IGP advertises existing 8 Bw values 1
  additional Bw value
• SP2 uses P0P1 for Voice, P2P3P4 for Data
• IGP advertises existing 8 Bw values 2
  additional Bw values
• SP3 uses P0 for Voice, P1for Low-loss Data, P2P3
  for BE
• IGP advertises existing 8 Bw values 3
  additional Bw values

() except P0 which is always advertised
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Issue

• Bandwidth Reservation Scheme
• how to compute unreserved Bw for each CT?
• proposal one simple model ()
• Max Reservable CT1/EF50
• Max Reservable CT0/BE100
• Currently established CT1/EF LSPs 20
• Currently established CT0/BE LSPs 30
• gt Unresvd EF 30 ( 50-20) Unresevd BE
  50 ( 100-30-20)

() investigating potential enhancements
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Proposal

• Should TEWG take ownership of DS-TE
  Requirements document?(currently owned by MPLS
  WG)

21
Proposal

• If yes, turn ltdraft-ietf-mpls-diff-te-reqts-00.txt
  gt into a TEWG document instead of MPLS WG
  document.

22
Proposal

• Protocol extensions to satisfy DS-TE Requirements
  remain in the WG responsible for the protocol
• RSVP-TE/CR-LDP/MPLS MIBs gt MPLS
  WG(draft-ietf-mpls-diff-te-ext-00.txt)
• OSPF gt OSPF WG(draft-lefaucheur-diff-te-ospf-00
  .txt)
• ISIS gt ISIS WG (draft-lefaucheur-diff-te-isis-0
  0.txt)