May 21, 2013 Deploying Global Server Load Balancing Using Persistent Methods Sam Cohoon

May 21, 2013

Deploying Global Server Load BalancingUsing Persistent Methods

Sam Cohoon

© 2013 Citrix

Global Server Load Balancing

© 2013 Citrix


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What is GSLB?

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DNS

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The Citrix NetScaler implementation of Global Server Load Balancing GSLB is Domain Name System (DNS) based.

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DNS

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GSLB Typical Setup

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Global Server Load Balancing Components

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Components

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How it works - Summary

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DNS and MEPComponents: GSLB domain, GSLB site, GSLB vserver, GSLB service

Global Server Load Balancing Configuration

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GSLB Configuration

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Where do I start?

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GSLB Wizard

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GSLB DNS DOMAIN

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GSLB Methods

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GSLB Methods

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GSLB Methods

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GSLB Sites

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GSLB Sites

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GSLB Sites

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GSLB Service

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Configuration Summary

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Configuring Authoritative DNS - ADNS

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GSLB Visualizer

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Synchronizing Configuration

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Each Netscaler needs one Local GSLB site and all the other Remote sites.

All sites need the same configuration.

There is a GSLB configuration synchronization option.

Customizing your GSLB Configuration

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GSLB Load Balancing methods

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The NetScaler GSLB methods: Round Trip Time (RTT)Static Proximity

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Local DNS IP (LDNS)

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IP address that is being tested against is not an actual client IP address

it is the nameserver that is resolving the IP address on behalf of the client.

We refer to this as the “LDNS” IP address for the client’s local DNS IP address.

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GSLB Static Proximity

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IP-address based static proximity database is a UNIX-based ASCII file.

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GSLB Static Proximity Troubleshooting

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nsmap -t –d

root@test# nsmap -t -dEnter IP address to to test (dot notation) or q to exit:

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GSLB Static Proximity Troubleshooting

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> show locationparameterStatic Proximity----------------Database mode: Not applicableFlushing: Idle; Loading: IdleContext: geographicQualifier 1 label: ContinentQualifier 2 label: CountryQualifier 3 label: RegionQualifier 4 label: CityQualifier 5 label: ISPQualifier 6 label: OrganizationLocation file (format: Not applicable): Not loadedLines: 0 Warnings: 0 Errors: 0Current static entries: 0 Current custom entries: 0 Done

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GSLB Dynamic RTT

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Dynamic RTT : measure from each “site” NetScaler to the remote LDNS

Three Monitors:Ping of IP address (LDNS-PING)DNS TCP probeDNS UDP query

Global Server Load BalancingPersistence

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Persistence Based on Source IP

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The GSLB virtual server is responsible for DNS-based site persistence, and it controls the site persistence

Persistence Table

All sites must use the same set of persistence identifiers on the GSLB virtual servers.

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GSLB Persistence – Source IP Troubleshooting

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GSLB Persistence – Source IP Troubleshooting

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Global Server Load BalancingHTTP Cookie Persistence

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Persistence Based on HTTP Cookies

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HTTP-request level Connection proxy

HTTP redirect.

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HTTP Connection Proxy

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If the client gets sent to the wrong site:

The other site creates a connection to the GSLB site that inserted the site cookie, and proxies the client request

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HTTP Connection Proxy

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HTTP Redirect Persistence

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Redirect persistence can be used only: For HTTP or HTTPS protocols. If the domain name in the request is a GSLB DomainWhen a backup VIP or a GSLB local service is DOWN

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GSLB Persistence – HTTPRedirect

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GSLB Persistence – HTTP Redirect

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Global Server Load BalancingTroubleshooting

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GSLB Troubleshooting

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> sh gslb site

1) 10.217.245.104_siteB (10.217.245.104) Site Type: LOCAL

Metric exchange: ENABLED Public IP: 10.217.245.104

Network metric exchange: ENABLED Persistence session exchange: ENABLED

Trigger Monitors: ALWAYS

2) 10.217.147.70_siteA (10.217.147.70) Site Type: REMOTE

Metric exchange: ENABLED Site Metric MEP Status: DOWN Public IP: 10.217.147.70

Network metric exchange: ENABLED Persistence session exchange: ENABLED

Trigger Monitors: ALWAYS

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> sh gslb vserver

1) www.example.com_gslbvs_b - HTTP State: UP

DNS Record Type: A

Last state change was at Thu Apr 11 22:17:28 2013

Time since last state change: 11 days, 23:01:56.670

Configured Method: LEASTCONNECTION

Current Method: Round Robin Reason: Bound service's state changed to UP

BackupMethod: ROUNDROBIN

No. of Bound Services : 2 (Total) 1 (Active)

Persistence: SOURCEIP

Persistence Mask: 255.255.255.255 Persistence v6MaskLength: 128

Persistence Timeout: 2 min Persistence ID: 2

Disable Primary Vserver on Down: DISABLED Site Persistence: ConnectionProxy

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> sh gslb service1) 10.217.245.107_80_gslbsvc (10.217.245.107: 80)- HTTP Server: 10.217.245.107 State: UP

Effective State: UP

Max Conn: 0 Max Bandwidth: 0 kbits

PublicIP: 10.217.245.107 PublicPort: 80

Type: LOCAL Site Name: 10.217.245.104_siteB

Site Prefix: SiteB Site Persistence: ConnectionProxy

Threshold: BELOW Monitor Threshold : 0

2) 10.217.147.71_80_gslbsvc (10.217.147.71: 80)- HTTP Server: 10.217.147.71 State: DOWN

Effective State: DOWN

Max Conn: 0 Max Bandwidth: 0 kbits

PublicIP: 10.217.147.71 PublicPort: 80

Type: REMOTE Site Name: 10.217.147.70_siteA

Site Prefix: SiteA Client IP: DISABLED

Down state flush: DISABLED

Site Persistence: ConnectionProxy

Threshold: BELOW Monitor Threshold : 0

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root@ns# nsconmsg -K newnslog -d stats | grep gslb

root@ns# nsconmsg -g glsb -d current -s disptime=1

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Resources

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http://support.citrix.com/proddocs/topic/netscaler-traffic-management-10-map/netscaler-gslb-gen-wrapper-10-con.html

http://support.citrix.com/article/CTX122619

http://support.citrix.com/article/CTX123976


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Before you leave…

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May 21, 2013 Deploying Global Server Load Balancing Using Persistent Methods Sam Cohoon