1 © 2005 Cisco Systems, Inc. All rights reserved. DC-1102 11324_05_2005_X2 FUNDAMENTALS OF...

1© 2005 Cisco Systems, Inc. All rights reserved.

DC-110211324_05_2005_X2

FUNDAMENTALS OF NETWORKING FOR BUSINESS CONTINUANCEDisaster Recovery Overview


DC-110211324_05_2005_X2

In a NutshellElements of the Solution

DR/BC MetricsPolicies are adopted after Business Risk Assessment, determine tolerance for data loss and recovery time.

Metrics to measure business impact

• RTO• RPO• RAO

DR/BC MetricsPolicies are adopted after Business Risk Assessment, determine tolerance for data loss and recovery time.

Metrics to measure business impact

• RTO• RPO• RAO

Data Center Inter-Connect

Campus

Metro

Regional & National

Data Center Inter-Connect

Campus

Metro

Regional & National

Data ProtectionContinuous Data Protection

Array Based Data Replication

Synchronous

Asynchronous

Data ProtectionContinuous Data Protection

Array Based Data Replication

Synchronous

Asynchronous

Site Selection Routing End Users to Applications

Different Site Selection Mechanisms

Site Selection Routing End Users to Applications

Different Site Selection Mechanisms


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Enterprise RPO, RTO and RAO Policy

• Recovery Point Objective (RPO)

What is the cost and impact of data loss?

How much data loss is tolerable in event of disaster or failure?

• Recovery Time Objective (RTO)

What is the maximum tolerable outage?

When must operations resume after a disaster?

• Recovery Access Objective (RAO)

How long to access recovered data and applications?

RPO + RTO measurable targets for BC/DR, and underlying Data Center, Application and Storage

RAO measurable target for underlying Network Infrastructure convergence and client access to Applications in the Data Center


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Recovery Time Objective and Recovery Point Objective

• How current or fresh is the data after recovery?

• How quickly can systems and data be recovered?

time

Disasterstrikes

time t1 time t2

Systems recoveredand operational

Recovery time

ExtendedCluster

ManualMigration

TapeRestore

secs mins hours days weeks

$$$ Increasing cost

Recovery point

SynchronousReplication

secsminshoursdays

AsynchronousReplication

PeriodicReplication

Tapebackup

time t0

$$$ Increasing cost

Critical data is recovered


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Recovery Access Objective (RAO)User to Applications

time

Disasterstrikes

time t1 time t2

Systems recoveredand operational

Recovery time

time t3

Accessing recovered &operational systems

(t2) Recovery Time Objective(t3 – t2) Recovery Access Objective

Networks have converged to provide a path to the applications and data


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DATA CENTER INTERCONNECT

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Data Center Interconnect Options

Data Center Core

Aggregation

Access

Core

Access

Servers

Storage

SONET/SDHNetwork

DWDMNetwork

Campus Core

IBM

Metro Ethernet

DC Interconnect

WAN

GE

IBM GDPS

1/2 Gb FC/FICON


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Data Center Transport Interconnect Technologies for IP Transport

Dark Fiber

CWDM

DWDM

SONET/SDH

IP

Data Center Campus Metro Regional National

Increasing Distance

Multi-Services

2Gbps

2Gbps lambda

T1 or E1, T3 or E3, HSSI, ATM, PoSFCIP

iSCSI

Gig

E o

ver

Op

tica

l

T1 or E1, T3 or E3, HSSI, ATM, PoS


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Data Center Transport Interconnect Technologies for SAN Extension

Dark Fiber

CWDM

DWDM

SONET/SDH

FC

IP

Data Center Campus Metro Regional National

Increasing Distance

Sync

Sync (2Gbps)

Sync (2Gbps lambda)

Sync

Sync (Metro Eth)

Async

Async (1Gbps+)

Async (< OC-12/STM4)

Async (< OC-12/STM4)

Sonet/GigE

Various WAN transports…

…. Async (< DS3/E3)

Op

tica

l Distance dependent on available BB_Credits

BB_Credit Spoofing for

extended distance


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CWDM: Coarse WDM

• “Colored” CWDM SFPs (or GBICs) used in FC switches (no transponder)

• Optical multiplexing done in CWDM OADM (optical add/drop multiplexer)

Passive (unpowered) device—Just mirrors and prisms

• Up to 30dB power budget (36dB typical) on SM fiber

~100km point-to-point or ~40km ring

• Provides for Client protection

1470nm

1490nm

1510nm1530nm

1550nm1570nm1590nm

1610nm

1470nm

1490nm

1510nm1530nm

1550nm1570nm1590nm

1610nm

Mux/Demux

Mux/Demux


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DWDM: Dense WDM

• Higher density than CWDM

32 lambdas or more (protected) channels in narrow band around 1550nm at 100GHz spacing (0.8nm)

EDFA amplifiable longer distances

Carrys 1, 2, 4 Gbps FC, FICON, GigE, 10GigE, ESCON, IBM GDPS

• Data Center to Data Center

• Protection options: Client, splitter, or linecard


DC-110211324_05_2005_X2

Coarse vs. Dense WDM

Coarse

(CWDM)

Dense

(DWDM)

Wavelengths Max 8 >8 (32 or more Protected)

Spacing 20 nm (1470nm–1610nm) 0.8 nm

AmplifiableNot w/ conventional EDFA

(1550nm only)YES

Cost LOW HIGH

ApplicationMetro Access

Campus and Data CenterLarge Enterprise/Service

Provider

Protection Available No Yes

TypeCharacteristic


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Metro Ethernet OptionWhat Does Ethernet as a LAN/MAN/WAN Transport Offer?

• Ethernet becomes the ubiquitous interface: single technology for LAN, MAN and WAN

• Efficient frame-based infrastructure: IP friendly

• Cost effective interface with flexible bandwidth offerings: 10/100/1000/10000 Mbps

• Geographical independence: Ethernet over Optical, IP or MPLS


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Ethernet Wire Service (EWS)

• Defines a point-to-point, port-based service

• No service multiplexing—“all-to-one” bundling

• Transparent to customer BPDUs

• Routers and switches can safely connect

PE CPE

SPIP/MPLS/

SONET/SDHNetwork

PE

PE

Pseudowires

NON-ServiceMultiplexed UNI

802.1Q TunnelingALL to One Bundling

CPE

CPE


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Ethernet Relay Service (ERS)

• Defines a VLAN-based point-to-point service (analogous to Frame Relay using VLAN tags as VC IDs)

• Service multiplexed UNI (e.g. 802.1Q trunk)

• Opaque to customer PDUs (e.g. BPDUs)

• Router as CPE edge device

CPE PE

802.1Q Trunk

SPIP/MPLS/

SONET/SDHNetwork

PE

PE

CPE

CPE

CPEPseudowires

ServiceMultiplexed UNI

VLANs


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SITE SELECTION

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Site Selection TechnologiesRecovering the Front End Network

• Front End Network: DNS, RHI and BGP

DNS (Application Aware)

Used for load distribution,

and proximity

Route Health Injection

(Application Aware)

BGP

(application unaware)

Content Switch• Active Standby Sites• Load Distribution using IP Routing

Content Router• Active Active Sites• Different Load Distribution algorithms


DC-110211324_05_2005_X2

Overview Site-Selection

Storage Network

Secondary Data Center

FC SAN

RAID

FCIP

Storage Network

Primary Data Center

FC SAN

RAID

FCIP

Customer/Partner

Employee

WANWANInternet

or Intranet

SiteSelection


DC-110211324_05_2005_X2

Active/Standby

InternetISPA

Corporate WAN

ISPB

Primary for application 1

Primary for Application 2

Each application can have a unique IP

address

DC1 DC2

Secondary for application 2

Secondary for application 1


DC-110211324_05_2005_X2

• Advantages

Typical Phase I deployment

Could be implemented without the intelligent site selection front end (GSLB)

• Disadvantages

Delay in failover manual switchover if without GSLB

Under utilization of resources with no load sharing

Active/Standby (cont)


DC-110211324_05_2005_X2

Active/Active

InternetISPA

Corporate WAN

ISPB

Active for application 1


Each application has 2 IP addresses

DC1 DC2




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• Advantages

Better use of resources due to load sharing

Quick failover with no manual intervention

• Disadvantages

Data mirroring in both directions

Session persistence needs special care

Active/Active (cont)


DC-110211324_05_2005_X2

Load Distribution

InternetISPA

DC1 DC2

Corporate WAN

ISPB

DNS server

ContentRouter

DNS server

ContentRouter

DNS resolution

Load distribution


DC-110211324_05_2005_X2

Load Distribution Considerations

• Is the application stateful or stateless?

Stateful applications need dns source-ip-hash methods or ACLs for static DNS mappings

Stateless applications are easier to implement

• Are the clients coming from a mega-proxy (NAT’ed) environment?

This might break the dns source-ip-hash methods

Consider static DNS mappings with ACLs


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DATA REPLICATION

25252511324_05_2005_X2


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Data Replication Objectives

• Get the data to a recovery site – RPO

• Enable rapid restoration – RTO

• Facilitated by the SAN extension transport


DC-110211324_05_2005_X2

Replication and Mirroring Alternatives

• Disk replication

Transparent to host

Managed by disk subsystem

e.g. EMC SRDF, HP CA EVA, HDS Truecopy, IBM PPRC, and others

• Continuous Data Protection (CDP)

e.g. SANTap


DC-110211324_05_2005_X2

Array Based Replication: Concept

• Two arrays located on extended fibre channel fabric

• Read from local array

• Changes (Writes) replicated to remote array

Replication managed by software in storage arrays

Host server is unaware of replication

Implementations are proprietary

EMC: SRDF

HDS: Truecopy

HP: CA EVA

IBM: PPRC

And others …

• Multiple modes of operation

Remote Storage

Array

Local Storage

Array

Host Server

1. Host Writes to local intelligent

storage array

2. Storage array software replicates changes

(writes) to remote array

Normally Involves Two

Round Trips per Write over Fibre

Channel


DC-110211324_05_2005_X2

Replication: Modes of Operation

Synchronous—All data written to cache of local and remote arrays before I/O is complete and acknowledged to host

Asynchronous—Write acknowledged after write to local array cache; changes (writes) are replicated to remote array asynchronously


DC-110211324_05_2005_X2

SAN ExtensionNetwork

Synchronous Replication: I/O Detail

Remote Storage Array

LocalStorage Array

Host Server

Write, LUN=5, LBA=12345, DL=8kB

Transfer Ready

FCP Data (2kB frames)

SCSI Status=good

I/OServiceTime Write, LUN=5, LBA=12345, DL=8kB

Transfer Ready


SCSI Status=good

t t t

RoundTrip

RoundTrip

Write I/O Is Complete at This Point—Local and Remote Arrays Identical


DC-110211324_05_2005_X2

SAN ExtensionNetwork

Asynchronous Replication: I/O Detail

RemoteStorage Array

Host Server


Transfer Ready


SCSI Status=good

I/O Service Time


Transfer Ready


SCSI Status=good

Response from Local Array Returned Independently of Replication Process; IO Complete, But Arrays Not Identicalt t t

Round Trip

Round Trip

LocalStorage Array

Replication Process and Protocol Is proprietary; Example Shows One

Implementation


DC-110211324_05_2005_X2

SAN Extension for Data Replication

• Extend the normal reach of a Fibre Channel fabric

FC over SONET

FC over IP (FCIP)

Optical (DWDM, CWDM)

FC FC

SAN Extension Network

Replication

Shared Data Cluster

Remote Host Access to Storage


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Fibre Channel Write Acceleration (FC-WA)

• ProblemPerformance of DR/BC applications inhibited by distance

• SolutionOvercome limitations of SCSI writes

FC write acceleration with SSM module on both ends

Minimizes application latency

• Primary applicationsSynchronous replication

• BenefitsUp to 25% increase in performance on synchronous application

Extend Distances for DR/BC Applications

Primary Data Center DR Data Center

SSM SSM

FC WA


DC-110211324_05_2005_X2

Fibre Channel Write Acceleration

FC FC

WRITE

XFER_RDY

DATA

STATUS

FC FC

WRITEXFER_RDY

DATA

STATUS

FC FC

XFER_RDY

SSM Module SSM Module

Without FC Write Acceleration With FC Write Acceleration

Reduction in Latency ofat Least One I/O

• Requirements for FC write accelerationSSM moduleBoth initiator and target must be directly attached to the SSM module

• Benefits of FC write accelerationImproves response time for the storage applicationsExtended distance for BC/DR applications without performance impact


DC-110211324_05_2005_X2

SAN Extension Design: High Availability

• Port channels increase resilience for high availability with FC or FCIP links

Appears as a single logical link (Up to 16 member links)

Protecting the fabric from network failure

Route portchannel member links over diverse geographic paths

Load balancing on SRCID/DESTID or SRCID/DESTID/OXID basis (Unidirectional per VSAN)

SCSI exchange is smallest atomic unit, so frame order kept intact

Site B

Site AFC

FC

PortChannels


DC-110211324_05_2005_X2

Summary

• Determine the right RPO, RTO, and RAO for your business needs

• Recovering the front end mechanisms:

BGP

RHI

DNS

• Recovering the back end:

Data Replication & SAN Extension

• Transport options between Data Centers

CWDM

DWDM

SONET/SDH

Pure IP (e.g.: IP VPN)

Metro Ethernet (Ethernet/GigE/10GigE)

1 © 2005 Cisco Systems, Inc. All rights reserved. DC-1102 11324_05_2005_X2 FUNDAMENTALS OF...

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Transcript of 1 © 2005 Cisco Systems, Inc. All rights reserved. DC-1102 11324_05_2005_X2 FUNDAMENTALS OF...