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Case for Segment Protection or Local Repair. M Vinod Kumar Tejas Networks. Agenda. Statistics Few Problem Statement What else can be taken care of? Other benefits Working of SPS-TE. Impact of Outage Times. Reason for Service Outage. Misconfiguration: Easily corrected

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case for segment protection or local repair

Case for Segment Protection or Local Repair

M Vinod Kumar

Tejas Networks

IEEE Interim, Seoul, Sept 08

agenda
Agenda
  • Statistics
  • Few Problem Statement
  • What else can be taken care of?
  • Other benefits
  • Working of SPS-TE
reason for service outage
Reason for Service Outage
  • Misconfiguration: Easily corrected
  • Resource failure: Major cause of outage
    • Fiber cut:
      • 100 to 1000 times frequent than node failure
      • Metro – 13 cuts every 1000 mile per year
      • Long Haul – 4 cuts every 1000 mile per year
    • Node failure:
      • Software
      • Hardware
fiber cut in usa 1993
Fiber cut in USA, 1993

Cumulative

Source: FCC

diagnosis of 1993 fiber cuts in us
Diagnosis of 1993 fiber cuts in US

60% Dig-ups

Source: D. Crawford, 1993

now consider india
Now consider India
  • 10000 cuts per year!

Annual Addition

real failure numbers
Real Failure Numbers
  • With over 4,00,000 (4 lakh) rings, Indian Service Providers report multiple fiber cuts per day.
    • Provider-A report 15 planned cuts and 5 unplanned cuts per days
    • Provider-B report 8 cuts per day on an average
  • Service Providers know that certain links are more prone than others
    • Up-coming area
    • Rain/Flood/Rodent prone area
what about other countries
What About Other Countries?
  • All developing countries face similar problems that developed countries faced 10 years ago.
n 1 requirement

x

To Router

(Dual Home)

x

x

Regional

Aggregation

x

x

x

Metro

Aggregation

x

x

Access

N:1 Requirement

Aggregation nodes subtends multiple and diversely routed aggregation rings

Aggregation node subtends multiple access ring

Access ring is getting smaller

requirements from indian service provider translated to qay requirements
Requirements from Indian Service Provider Translated to Qay Requirements
  • Segment Protection models must include N:1 and should include 1:N and M:N including priority/pre-emption .
    • In case of 1:N model, higher priority tunnels/I-SID can pre-empt lower priority tunnels/I-SID, if required
    • In case of N:1 model, multiple segments can have priorities P1, P2, P3, P4 depending on the degree of protection switching needed. Typical carrier wants very fast switching (sub-50ms) of the traffic along pre-provisioned segment/path for degrees ranging between 3-10
    • N:1 protection is like static routes for specific DA/VID combination with priorities P1, P2, P3 and P4 etc. In the event of the failure of P1 segment, traffic (DA/VID and associated I-SIDs) switches to P2 segment, provided it is ENABLED (Administrative Control) and healthy (Status = UP), otherwise move the traffic to P3.
working of segment protection

Working of Segment Protection…

IEEE Interim, Seoul, Sept 08

present scheme link protection
Present Scheme: Link Protection

BEB#2

BEB#1

BCB

BCB1

BCB2

TESI#1

BEB#4

TESI#2

BEB#3

  • Single link failure between BCB1 and BCB2 can result in multiple TE protection switchover
  • In practice, many ESPs may be sharing a set of link (s) or/and node (s)

BCB3

proposed segment protection
Proposed: Segment Protection

BEB#2

BEB#1

BCB

BCB1

BCB2

BEB#4

TESI#1

TESI#2

BEB#3

Have end-to-end protection along with local protection

BCB3

present scheme group failure
Present Scheme: Group Failure

BEB#2

BEB#1

BCB

BCB1

BCB2

BEB#4

BEB#3

BCB3

proposed segment protection1
Proposed: Segment Protection

BEB#2

BEB#1

BCB

BCB1

BCB2

BEB#4

TESI#1

TESI#2

BEB#3

Have end-to-end protection along with local protection

BCB3

present scheme one link disjoint protection
Present Scheme: One Link-disjoint Protection

BEB#2

BEB#1

BCB

BCB1

BCB2

BEB#4

BEB#3

BCB3

proposed segment protection2
Proposed: Segment Protection

BEB#2

BEB#1

BCB

BCB1

BCB2

BEB#4

BEB#3

Inefficient to do global switching when there is cut

Have end-to-end protection along with local protection

BCB3

proposed segment protection3
Proposed: Segment Protection

ESP#1

ESP#2

Bypass a node or multiple nodes/links by properly configuring the MD and MEPs

segment protection in p to mp case
Segment Protection in P-to-MP case

p-to-mp TESI

The tree branch can be protected independently

segment protection can scale to multiple domains
Segment Protection Can Scale to Multiple Domains

MD#A

MD#B

  • MD#C

ESP#1

ESP#2

  • PBB-TE (Qay) TESI as segments for Domain level protection
summary requirements
Summary: Requirements
  • Segment Protection Switching (SPS) shall offer n:1
  • SPS should support m:n protection
  • Segment faults should be repairable through priority module
    • Priority module should take outage time impact into consideration
  • Segments shall be provisioned and dynamic after all provisioned segment fails
  • SPS should increase network utilization
    • Segment protection should prevent re-tracking of service
  • SPS should report if fault is on left or right side of the segment
  • SPS must tell if fault is in a service, collection of service, all the services, work segment or protect segment
    • Include explicit link failure along the Primary Segment
    • Include forwarding failure on a transit node along the Primary Segment.
  • Overlapping of Multiple segments should be allowed
  • Nesting of Segments should be allowed
  • SPS is more generic than IEEE 802.1Qay PBB-TE
clarification on n 1
Clarification on N:1
  • Use pre-provisioned protection segments for rapid 50ms protection upto 3:1
  • Use dynamic protection after 3:1 fails
  • Combination of pre- and dynamic provisioned protection segments
working of sps te
Working of SPS-TE
  • Link to SPS-TE
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