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1 Presentation_ID © 1999, Cisco Systems, Inc. Introductions to ISP Design Fundamentals Introductions to ISP Design Fundamentals
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Page 1: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

1Presentation_ID © 1999, Cisco Systems, Inc.

Introductions to ISPDesign FundamentalsIntroductions to ISP

Design Fundamentals

Page 2: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

2Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

AgendaAgenda

• Rational Behind ISP Network Design

• Point of Presence Topologies

• Adding Services to the Architecture

• Impact of Services on the Network

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3Presentation_ID © 1999, Cisco Systems, Inc.

Rational Behind ISPNetwork Design

Rational Behind ISPNetwork Design

Layers upon Layers upon Layersupon Layers …...

Layers upon Layers upon Layersupon Layers …...

3Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

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4Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

The Free On-line Dictionaryof Computing

The Free On-line Dictionaryof Computing

Architecture: Design; the waycomponents fit together;

it may also be used for anycomplex system, e.g. “software

architecture”, “networkarchitecture”

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5Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Network Design andArchitecture…

Network Design andArchitecture…

• … can be critical

• … can contribute to the successof the network

• … can contribute to the failureof the network

Page 6: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

6Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

No amount of magicknobs will save a

sloppilydesigned network

Paul Ferguson—Consulting Engineer,Cisco Systems

Ferguson’s Law ofEngineering

Ferguson’s Law ofEngineering

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7Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

What Is a Well-DesignedNetwork?

What Is a Well-DesignedNetwork?

• One that takes into considerationsome main factors

3 Topological/protocol hierarchy

3 Redundancy

3 Addressing aggregation (IGP and BGP)

3 Scaling

3 Policy implementation (core/edge)

3 Management/maintenance/operations

3 Cost

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8Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

One Must Acknowledge that…One Must Acknowledge that…

• Two different worlds exist

3One world revolves around privateorganizational networks and anotherconcerns the global Internet

• Growth in the Internet is faster thanany other technology introduced tothe public-at-large

Page 9: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

9Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Source: Forbes Magazine July 7th—1997

Internet

CellPhone

PC

TV

Radio

MicrowaveMicrowave

VCR

Airplane

TelephoneTelephone

Car

Electricity

Technology AdoptionTechnology Adoption

Page 10: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

10Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

If you’re not scared yet,you don’t understand the

problem!Mike O’Dell—Chief Scientist,

UUnet

Scaling is the #1 Problem onthe Internet

Scaling is the #1 Problem onthe Internet

Page 11: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

11Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Core Influences to ISP DesignCore Influences to ISP Design

• Modular Design

• Functional Design

• Tiered/Hierarchical Design

• Multiple Levels of Redundancy

• Routing Protocol Hierarchy

• Build for IP Forwarding First - thenadd services

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12Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Modular DesignModular Design

Backbone linkto another PoP

Backbone linkto another PoP

Nx64 customeraggregation layer

Nx64 leased line circuit deliveryChannelised T1/E1 circuits

T1/E1 leased line circuit deliveryChannelised T3/E3 circuits

NetworkOperations

Centre

Consumer

DIAL Access

Other ISPs

Consumer Cable

and xDSL Access

NetworkCore

ISP Services(DNS, Mail, News,

FTP, WWW)

Hosted Services

NxT1/E1 customeraggregation layer

Organize the Networkinto separate andrepeatable modules

3 Backbone

3 POP

3 Hosting Services

3 ISP Services

3 Support/NOC

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13Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Functional DesignFunctional Design

• One Box cannot do everything! (no materhow hard people have tried in the past)

• Each router/switch in a network has awell-defined set of functions.

• The various boxes each with afunction interact with each other.

• ISP Networks are a systems approachto design.

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14Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Tiered/Hierarchical NetworkDesign

Tiered/Hierarchical NetworkDesign

Access Layer

DistributionLayer

Other Regions

Other Regions

Other Regions

Core• Flat - MeshedTopologies havenot scaled.

• Hierarchy is usedin network designsto scale thenetwork.

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15Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Intra-POP Interconnect

Border

Backbone

Access

Multiple Levels of RedundancyMultiple Levels of Redundancy

• Triple Layered POPRedundancy

3 Lower-level failures are better

3 Lower-level failures may triggerhigher-level failures

3 L2: Two of everything at

3 L3: IGP and BGP provideredundancy and load balancing

3 L4: TCP re-transmissionsrecovers during the fail-over

POP IntraconnectPOP Intraconnect

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16Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Multiple Levels of RedundancyMultiple Levels of Redundancy

PoP

BackbonePeer

Networks

Residential Access

LocationAccess

• Objectives -

3 As little user visibility of a fault as possible

3 Minimize the impact of any fault in any part of thenetwork.

3 Network needs to handle L2, L3, L4, and Routerfailure

Page 17: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

17Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Hierarchy of RoutingProtocols

BGP4and OSPF/ISIS

FDDI

Other ISPs

CustomersLocalIXP

BGP4 Static/BGP4

BGP4

Page 18: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

18Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

WarningWarning

Beware Block Diagram/SlidewareDesign Gurus! They have gottenpeople and networks into trouble

- including Cisco

Page 19: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

19Presentation_ID © 1999, Cisco Systems, Inc.

Point of PresenceTopologies

Point of PresenceTopologies

19ISP/IXP Workshops © 1999, Cisco Systems, Inc. www.cisco.com

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20Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

PoP DesignPoP DesignCore Backbone

Routers

POPInterconnect

Medium

NeighboringPOP

NeighboringPOP

Dedicated Access PSTN/ISDN

Core 1 Core 2

SW 1 SW 2

Access 1 Access 2 NAS 1 NAS 2

External BGP Peering

Page 21: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

21Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

45 Mb/s HSSI

FDDI

InternetInternetBackboneBackbone

Early Internet POPArchitecture - NSPEarly Internet POPArchitecture - NSP

3Backbone trunksat 45 Mb/s

3Shared mediainterconnectwithin POP:

FDDI, Ethernet, SwitchedEthernet

3ConventionalT3 backboneInternet router

Page 22: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

22Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

155 Mb/sPOS/ATM

XX

Internet Internet BackboneBackbone

3Backbone trunksat 155 Mb/s

Packet over SONET OC3

ATM OC3

3Switched interconnectwithin POP:

Switched FDDI/Fast Ethernet

ATM OC3

3Advanced OC3 backboneInternet router

Internet POP Architecture -‘96/’97

Internet POP Architecture -‘96/’97

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23Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

622 Mb/sPOS/ATM

622 Mb/s ATM1 Gb/s Ethernet

Duplex Fast E, 155/ 622 Mb/s ATM, or1 Gb/s Ethernet

InternetInternetBackboneBackbone

3 Backbone trunks at622 Mb/s

Packet over SONET OC12ATM OC12

3 Switched interconnectwithin POP:

ATM at OC3 AND OC12Ethernet ChannelGigabit Ethernet (early ’98)POSIP (late ‘98)

3 Gigabit OC12 backboneInternet router

Internet POP Architecture -‘97/’98

Internet POP Architecture -‘97/’98

Page 24: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

24Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

• SRP Rings - High Speedof SDH combined with fastfailover and redundancy

3High bandwidth

3Reduced port counts

3Reduced complexity

3Proactive self healing

Backbone

7xxx

GSRGSR

7xxx

7xxx

7xxx

7xxx

leased line aggregation

Internet POP Architecture -‘99/’01

Internet POP Architecture -‘99/’01

Page 25: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

25Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Large POPs - add a 3rd layerLarge POPs - add a 3rd layer

Internet Internet BackboneBackbone

3 Problem: port density!

3 Solution: buy more routers!

3 Customer routers connect toaggregation routers

Packet over SONET OC3

ATM OC3

3 Aggregation routers connect tobackbone routers

3 Scales nicely

3 X CRs to Y ARs to Z BRs

3...where X>Y>Z

3Be careful not tooversubscribe!

OC3

OC12

OC48

Page 26: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

26Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

FDDI100Mbps

POSN x 155

SRP2 x 622Mbpsor 2x2.5GB

Fast/Gig Ethernet100/1000Mbps

POP Interconnect SummaryPOP Interconnect Summary

Page 27: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

27Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Key Design Principles

• Interconnection forManagement, Security,and Accounting services

3 Netflow Devices -FlowCollector

3 Syslog collector for allnetwork devices

3 SNMP collector (PC BasedUNIX)

3 Security Auditing Tools(NetSonar)

POS

POS & ATM for Core Backbone

GSRGSR

75077507

Customer and Services

Management

&

Accounting

Page 28: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

28Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

ISP routing Architectures - IPISP routing Architectures - IP

• IGP = EIGRP, IS-IS,or OSPF

3 almost always IS-IS or OSPF

3 IS-IS, single level (usually L2)

3 OSPF, either single area or BB/POPareas

• BGP = all routers in full mesh

3 mesh accomplished with routereflectors, confederations, actual fullmesh

• All routers have all routes, soservices could go anywhere

Page 29: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

29Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

ISP routing Architectures -IP+MPLS

ISP routing Architectures -IP+MPLS

• IGP = EIGRP, IS-IS,or OSPF

3 must be IS-IS or OSPF to use MPLSTE

• BGP = only edge routers need full routes

3 full-mesh of edge routers usingaforementioned mechanisms

3 packets are forwarded via LDPlabels, not IP destination address

• Where to put your services?

3 cannot hang a cache service off of arouter that doesn’t have full routes!

Page 30: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

30Presentation_ID © 1999, Cisco Systems, Inc.

Adding Services to theArchitecture

Adding Services to theArchitectureCause and EffectCause and Effect

3015030925_04F9_c1 © 1999, Cisco Systems, Inc.

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31Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Services?How many Services?

Services?How many Services?

Edge (one-time) services

• Voice over IP

• MPLS VPNs

• CDNs

• VPDNs

• Managed services

• Dial—DSL—cable

Per-hop services

• MPLS packet forwarding

• DiffServ, other QoS

• Multicast Services

Most network services are applied at the edge!

Page 32: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

32Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Ask the Right QuestionsAsk the Right Questions

• What is the value of the service?

3 Technical merit

3 Cost savings

3 Marchitecture

• What is the cost of the service?

3 Equipment?

3 Training people to support it?

3 Network buildouts/topology changes?

Page 33: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

33Presentation_ID © 1999, Cisco Systems, Inc.

Impact of Services onthe Network

Impact of Services onthe Network

3315030925_04F9_c1 © 1999, Cisco Systems, Inc.

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34Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Who Knows?Who Knows?

• What will be the impact on existing trafficloads/patterns?

• Can the network deliver the performancethat your customers/applications desire?delay? jitter (delay variation)?

• Make sure to add capacity as you addservices - bandwidth is a must.

Page 35: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

35Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Deployment of New ServicesDeployment of New Services

• Is more of a business decision

• The technical aspect is to ensurecontinued network performance—scalability and stability

• Try to keep services within your AS

3end2end control

3less likelihood of failure/flaps

Page 36: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

36Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Deploying New ServicesDeploying New Services

• Don’t feed the hype fire

• Look before you leap!

• Don’t deploy new technologies andservices just for the sake of it; havevalid business and technical reasons

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37Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Deploying New ServicesDeploying New Services

• Usually a Service requires a TCP/UDPtermination (I.e. TCP’s three wayhandshake)

• Termination should happen out sideof the primary flow path

• Otherwise, the network is thendesigned around the single service.

Page 38: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

38Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Deploying New ServicesDeploying New Services

CPECPE POPPOP CORECORE

MultiplePOP Services

Interconnect Leased Core

ISDNPOTS

Lease LineCablexDSL

Access

Primary Packet Flow

ServiceTerminate

Here

Page 39: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

39Presentation_ID © 1999, Cisco Systems, Inc.

TransparentRedirection of a Flow

in the POP

TransparentRedirection of a Flow

in the POPFactors that went into the

design of WCCPFactors that went into the

design of WCCP

39Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

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40Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Design Objectives for the ISPDesign Objectives for the ISP

• Transparent Redirection of a IP flowbased on source, destination, and/orport number.

• Transparent Integration - norebuilding the POP to add thisservice.

• Failed open - if the service fails, itshould not effect the core IP servicenor any other services.

Page 41: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

41Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Design Objectives for the ISPDesign Objectives for the ISP

CPECPE POPPOP CORECORE

Interconnect Leased Core

ISDNPOTS

Lease LineCablexDSL

Access

Primary Packet Flow

WCCPServiceClusters

• Not to effect the primary packet flow of thePOP - if not redirected - then is CEF/dCEFSwitched!

Page 42: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

42Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Design Objectives for the ISPDesign Objectives for the ISP

CPECPE POPPOP CORECORE

Interconnect Leased Core

ISDNPOTS

Lease LineCablexDSL

Access

WCCPServiceClusters

• Work with the multi-level L2/L3 redundancyof the ISP POP. Equal paths in the IGP +CEF leads packet asymmetry.

Input PortWCCP

Redirect

Page 43: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

43Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Design Objectives for the ISPDesign Objectives for the ISP

CPECPE POPPOP CORECORE

Interconnect Leased Core

ISDNPOTS

Lease LineCablexDSL

Access

WCCPServiceClusters

• Provide the ISP with Flexibility on the pointof redirection. Do not force an architectureon the customer.

Page 44: ISP Design Fundelmentals - IPsynftp.ipsyn.net/pub/mirrors/cisco/public/cons/isp/documents/ISP_Design... · FDDI Internet Backbone Early Internet POP Architecture - NSP 3Backbone trunks

44Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com

Design Objectives for theService Group

Design Objectives for theService Group

• Linear Scalability with the Cache -minimize object replication.

• Fault Tolerance and Maintenance.

• “Joe Smith the Telco Tech” test.

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45Presentation_ID © 1999, Cisco Systems, Inc. www.cisco.com


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