Copyright VersaTel Telecom 2000 Marc Teichtahl Large Scale Packet Optimized Rings Part II.

Copyright VersaTel Telecom 2000Marc Teichtahl

Large Scale Packet Optimized Rings

Part II


Part One: The Design Brief

“effect the migration from traditional

transmission technologies to a next

generation platform optimized for the

transmission of purely packetized data”


The General Business Drivers

• Provide all services over IP based infrastructure

• Reducing costs & Increasing revenues = $PROFIT$

• Single management platform

• Ease of on-going operations and support

• Lower maintenance costs

• Lead the technology push into IP optics

• Influence the early adopters


Our Specific Business Drivers

• Utilize “owned” fiber network

• Match fiber topology against network architecture

• Decrease $/Mbps

• Shorten provisioning lead-time

• Shorten product time to market

• Provide “endless” scalability

• Allow for DWDM “plug & play”

• Provide forward consideration to MPLS and MPλS


50155 CAPEX(USD Millions)

PRODUCTS

IP Circuits

WAN Services

MPLS Services

Streaming Media

TECHNOLOGY

SDH/DPT

DPT

x4

x8

0Note: Revenues in millions USD

VOIP

WAN Carriage

????

The Business Drivers


Our Choices and Decisions

Key Challenges-:

• Mapping the topologies

• Matching segment parameters

• Designing optical regeneration

• SRP overhead considerations

• PoP Selection

• Fitting the rings together


To SDH or not to SDH ?

• SDH provides circuit capabilities

• DPT does not offer circuit capacity but pure IP

Does this impact our business model ?

• Lower unit revenue from IP sales – IP is cheaper

• Cheaper to implement DPT

Key factor to financial success

• Must yield high volume sales to be more profitable



• SDH will always have a higher incremental cost

• You still have to add the router

• SDH will yield a broader range of more profitable products

• DPT will offer pure optimised IP capacity



• Some segments may utilize SDH due to

• Optical Length or path loss

• Fibre requirements to close the ring


The Problems

• 9 Fiber Rings

• 35 PoP

• 3 Countries

• Geographical distances and optical limitations

• Traffic distribution

• Line card limitations

The Solutions

• International Core ring

• Local distribution rings

• Optical Regeneration

Mapping The Topologies


Mapping The Topologies - Logical

M ons

RotterdamDen Haag Alkmaar

S loterd ijkHaarlem

VersaTower Kru islaan

Breda Utrecht

Antwerpen

Luik

Hasselt

Leuven

Brussel

Charlero i

Kortrijk

G ent

Amersfoort

Zwolle

Deventer

Arnhem

Nijmegen

Leeuwarden

G roningen

Enschede

Den Bosch

M aastricht

Heerlen

Venlo

Eindhoven

ring A

ring B

ring Cring E

ring D

ring F

core ring

Antwerpen

R otterdam Slo terd ijk

D en Bosch

VenloBrusse l


Mapping The Topologies - Logical

Versatel F iber Distance and Attenuation

Design by: René Koning

Ow ner: Data Netw ork Developm ent

Revis ion Date: M arch 20 2000

Vers ion Agreed by:

65.2km14.0 dB

33.0km7.6 dB

58.0km12.5 dB

21.0km4.2 dB

53.0km12.2 dB

29.0km6.7 dB

57.8km12.3 dB

78.0km17.4 dB

35.5km8.9 dB

51.0km11.7 dB

64.8km13.1 dB

64.5km14.8 dB

30.0km6.9 dB

96.0km19.5 dB

31.0km7.1 dB

24.8km4.8 dB

85.7km18.7 dB

63.9km13.3 dB

80.0km18.4 dB

36.0km8.3 dB

61.0km14.0 dB

38.0km8.7 dB

79.0km18.1 dB

41.0km9.4 dB

31 km7.1 dB

Dist. and Attenuation(@ 1550nm)

52.0km9.5 dB

104.0km23.9 dB

105.0km24.2 dB

71.0km16.3 dB

Mons

Charleroi

75.0km17.3 dB

41.0km9.4 dB

61.0km14.0 dB

Luxembourg

150.0km34.5 dB

Namur

157.0km36.1 dB

42.0km9.7 dB

105.0km23.4 dB

56.0km12.9 dB

Kortrijk

30.2km6.9 dB

31.0km7.1 dB

Alkmaar

HaarlemSloterdijk

Kruislaan

VersaTower

Utrecht

Den Bosch

BredaRoosendaal

Rotterdam

Den Haag

Antwerpen

Gent

BrusselLeuven

Hasselt

Luik

Maastricht

Heerlen

VenloEindhoven

Nijmegen

Arnhem

Deventer

Enschede

Groningen

Leeuwarden

Zwolle

Amersfoort

11.0km2.5 dB

22.9km5.9 dB


Line Card Limitations

• Proprietary to Cisco

• Currently in IETF for standards ratification

• Optical path loss limitations of 25dB

• Currently limited to OC-48

• Maximum 32 SRP nodes per ring

• Slot capacity for OC-48 and OC-192


Matching Segment Parameters

• Each optical segment must be within the optical tolerance for all components

• Achieved by the use of optical regenerators

• On some paths consideration was given to using SDH

• Not used due to capacity constraints

• Unable to scale as quickly as a purely optical solution “plug&play”


Optical Regenerations

• Based upon tolerances of SRP line cards

• Maximum loss 25dB

• Maximum optical path length 80Km

• This was achievable due to the physical fibre paths and ability to easily splice where needed


Overhead Considerations

• SRP enforces additional overhead to SDH

• IPS only travels between adjacent nodes

• Topology discovery messages

• natively 32 bytes + 8 bytes per node

• sent every 5 seconds

• 10 node ring provides ~1.5Kbps for IPS

• This is negligible

• Total overhead = IPS+Topology Disc+Usage control

• For 10 nodes ~2Mbps

• On a OC-12 Ring overhead is ~0.31%


Overhead Considerations

Inter-node SRP Overhead

0102030405060708090

100

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31

Number of Nodes

Ove

r H

ea

d (

byt

es/

s)


PoP Selection

• PoPs selected on two criteria

• Commercial – ROI

• Technical

• Optical distances

• Proximity to IP interesting sites such as exchange points.


International Core Ring

OC-48 International core ring

• Based on Cisco 12016

• Covering route 1001.4Kms / 625.875Miles

• Utilizing 5 optical regenerators

• Optical loss tolerance 4.2dB<<OL<<24.2dB


Local Distribution rings

OC-12 Local distribution rings

• 8 Distribution rings

• Based on Cisco 12008

• Covering route > 3000Kms / 1875M

• Utilizing 19 optical regenerators


SRP Interconnect Issues

We require a ring interconnect methodology that allows for the overlay of a complex routing architecture.

Core R ing Core R ing

D istribution R ing

Local PoP


SRP Interconnect Issues

Unknown inter ring SRP issues.

• Statistical possibility of run away restore conditions

• Both Rings wrapping at same time

• Inter-Ring IPS over-head

• OC-48 -> OC-12 serialization issues


Routing Issues

• Use of a per PoP border router

• Utilizes ISIS and BGP

• DPT Overhead issues

• SDH comparisons


ATM

Transit

Standard PoP Design


PoP Router Designations

• Each PoP has a border router.

• Connected to distribution routers

–Speed of transport between PoPs in event of failure

–Lower costs

• Multiple full tables


• Each PoP has a designated “net” identifier

• All inter-PoP routes are kept as level-1

• All intra-PoP, core and distribution routes are summarized on the PoP border routers into level-2

• Dial supernets are summarized at the dial aggragation router into level-2

• Core only carries level-2 summary routes.

ISIS Configuration


• Summarization is only allowed at level borders

• Causes internal PoP summarization issues

• Maintainence of huge topology tables.

• Integration with legacy OSPF networks may still prove to be an issue in the future

• Lack of flexibility in route selection and metric preferences

ISIS Issues


• Ease of configuration

• Simple adaptation for MPLS

• Via ISIS-extensions for MPLS

• Convergence speeds

• Flexibility in PoP and “net” naming schemes

ISIS Benefits


• All PoP border and customer aggragation routers are bgp speakers

• Utilization of full mesh between the PoP

• Utilization of confederations on a per PoP basis

• Use of route reflectors in the PoP

BGP Design


BGP Design


• Optically aware IP

– Utilizing both IP layer and optical layer MPLS signaling we aim to provide intelligent IP lambda capacity

– Allowing the IP layer to request further capacity from the optical.

– Allowing the optical layer to request a layer three re-route to avoid optical “congestion”

The Future Vision


• Migration of dark fiber to an intelligent DWDM solution.

–Providing customer distribution rings at OC-48 and above.

• Provide intelligent optical switching

–Optical path selection and re-route

The Future Vision

Copyright VersaTel Telecom 2000 Marc Teichtahl Large Scale Packet Optimized Rings Part II.

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Transcript of Copyright VersaTel Telecom 2000 Marc Teichtahl Large Scale Packet Optimized Rings Part II.