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Global server load balancing
 

Global server load balancing

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  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved.
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved.
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved.
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved.
  • Methods behave the same as in traditional LB. But apply during the site selection stage instead.
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved. Interactive session Plenty of time for Questions & Answers Ask for Attendee Input as what they expect Citrix NetScaler Overview Topologies and Architecture Statistics Statistical Utility NSCLI Stat Command Logging Log Files / Syslog NetScaler Web Logging Utility (NSWL) Data Gathering Network Traces Simple Network Management Protocol (SNMP) Other Tools Nsapimgr and Nscachemgr Third Party Tools
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved. Interactive session Plenty of time for Questions & Answers Ask for Attendee Input as what they expect Citrix NetScaler Overview Topologies and Architecture Statistics Statistical Utility NSCLI Stat Command Logging Log Files / Syslog NetScaler Web Logging Utility (NSWL) Data Gathering Network Traces Simple Network Management Protocol (SNMP) Other Tools Nsapimgr and Nscachemgr Third Party Tools
  • Presentation Title Goes Here Insert Version Number Here © 2003 Citrix Systems, Inc.—All rights reserved. Interactive session Plenty of time for Questions & Answers Ask for Attendee Input as what they expect Citrix NetScaler Overview Topologies and Architecture Statistics Statistical Utility NSCLI Stat Command Logging Log Files / Syslog NetScaler Web Logging Utility (NSWL) Data Gathering Network Traces Simple Network Management Protocol (SNMP) Other Tools Nsapimgr and Nscachemgr Third Party Tools

Global server load balancing Global server load balancing Presentation Transcript

  • Global Server Load Balancing {GSLB}Presented By Don WilliamsManager Escalation / TRMCitrix Application Networking GroupAssistant PresenterSeema Vaibhav DubeyLead Escalation Engineer/TRMCitrix Application Networking Group
  • AgendaGSLB OverviewGSLB OperationDecision LogicsConfigurationDemonstration © 2007 Citrix Systems, Inc. — All rights reserved 2
  • GSLB Overview• Load balances services between geographically distributed locations• Typical uses include: • Distribution of network traffic across multiple sites • Reduction of application latency • Distribution of server load across multiple sites • Disaster recovery• Operates under many of the same general principles as LB but relies on DNS for directing client requests• GSLB is a way to share the state & status of various geographically distributed servers and balance the load © 2007 Citrix Systems, Inc. — All rights reserved 3
  • DNS Features• Record Types • AAAA, A, CNAME, NS, PTR, SRV, SOA• Recursion • Ability to look up addresses not owned by the NS• Negative Caching • Only happens in proxy mode• Any Queries • Respond to queries with type any• Delegation with NS records• DNS Views • Internal and External clients • Interface DNS expression • Interface throughput © 2007 Citrix Systems, Inc. — All rights reserved 4
  • AgendaGSLB OverviewGSLB OperationDecision LogicsConfigurationDemonstration © 2007 Citrix Systems, Inc. — All rights reserved 5
  • GSLB Typical DesignGlobal Server Load Balancing (GSLB) addresses the needs of a distributedInternet environment with Citrix NetScaler systems located in differentgeographic locations Public IP Private IP 1.1.1.1 172.22.8.100:80 192.168.100.11:80 svc1a Florida VslbA 192.168.100.12:80 svc2awww.testlab.com Vgslb Atlanta VslbB 172.206.65.10:80 svc1b Public IP Private IP 172.206.65.11:80 svc2b 2.2.2.2 172.22.8.200:80Allows to configure the system to direct DNS requests, from a client, to the best performing GSLB Site in a distributed Internet environment © 2007 Citrix Systems, Inc. — All rights reserved 6
  • GSLB Entities• Built on NetScaler load balancing environment and entity model• GSLB entities in the NetScaler environment (descending hierarchy) GSLB domain: Publicly resolvable domain (zone) the GSLB deployment responds as GSLB site: Top level entity for linking remote sites, sharing monitoring data. IP needs to be an NS owned address (MIP, SNIP) GSLB vserver: Linked to GSLB services, is the decision intermediary for directing clients’ requests to one of the site’s LB vservers. GSLB service: Monitoring link to the vserver to be load balanced vserver: Represents the servers and services being LB’d to clients service: Links to & monitors the service/server (http, https, etc) fronted by the vserver © 2007 Citrix Systems, Inc. — All rights reserved 7
  • GSLB Communications: Monitoring• MEP: Metric Exchange Protocol • Netscaler Internal Protocol to exchange state and health information over a TCP session, enabled by default • Connection establishment involves a secure RPC method • Connection is initiated from Lower site IP using NSIP by default • Port 3011 or 3009 {secure} on site’s public IP needs to be allowed on any blocking firewall • Site to site monitoring • Distributes site metrics, network metrics, persistence information • DNS queries get best suited response based on configured algorithm and information gathered through MEP © 2007 Citrix Systems, Inc. — All rights reserved 8
  • GSLB Communications: Monitoring• MEP can be disabled, but limits GSLB methods to RR, static proximity, source IP hash. All other methods revert to RR when MEP is off/inactive.  set gslb site siteA –metricExchange DISABLED• Monitoring • Only states Up or Down are learnt • Status is assumed to be equally good • Each DNS query gets the IP address of various participating GSLB sites in a round robin fashion• Advanced Monitors • Extended Content Verification {ECV} • User Scriptable Monitors © 2007 Citrix Systems, Inc. — All rights reserved 9
  • GSLB MEP DependenciesGSLB Methods MEP Enabled MEP Disabled Active *InActive Round Robin As Defined As Defined As Defined Static Proximity As Defined As Defined As Defined SRCIP Hash As Defined As Defined As Defined RTT(Dynamic Proximity) As Defined RR RR Least Conns As Defined RR RR Least Packets As Defined RR RR Least Bandwidth As Defined RR RR Least Response As Defined RR RR       * In the preceding table, MEP is enabled but is inactive due to external factors. For example, bad network connections, firewalls dropping packets, or mismatch in MEP configuration. © 2007 Citrix Systems, Inc. — All rights reserved 10
  • DNS Methods• Authoritative config: NetScaler answers the DNS query • Each NetScaler is locally configured for an authoritative GSLB domain. Create DNS records for each site in the configuration • Supported DNS record types: NS, A, AAAA, CNAME, MX, PTR, SRV and SOA • Zone transfers not supported • One or all NetScalers can be set to participate as authoritative• Proxy config: NetScaler passes domain requests to backend DNS server • If the NetScaler is authoritative for the requested zone, the NetScaler responds to the query • If the request is for a zone that is within the GSLB domain, the NetScaler responds with the address of optimal vserver in GSLB domain © 2007 Citrix Systems, Inc. — All rights reserved 11
  • DNS Options• DNS response options (set per gslb vserver) • MIR: Multi-IP Response, lookup returns all active VIPs with optimal VIP first in the response • EDR: Empty Down Response, if returned VIP is down, send positive response but no records• Backup Site • A site can be assigned to take over when all primary sites are down > bind gslb vserver gslb_VIP_A –domain www.gslbdomain.com –backupip 205.18.145.12 • When all the services behind this vserver go down, the GSLB domain will resolve to the backup site’s IP address © 2007 Citrix Systems, Inc. — All rights reserved 12
  • DNS views• Internal and External clients • add dns view privatesubnet • bind gslb service GSLB_SVC1 -view privatesubnet 192.168.10.25 • add dns policy pol1 "CLIENT.IP.SRC.IN_SUBNET(192.168.0.0/16)" -view privatesubnet • bind dns global pol1 1• Interface DNS expression • Answer based on the interface the request entered• Interface throughput • Answer based on the throughput of the interface © 2007 Citrix Systems, Inc. — All rights reserved 13
  • AgendaGSLB OverviewGSLB OperationDecision LogicsConfigurationDemonstration © 2007 Citrix Systems, Inc. — All rights reserved 14
  • GSLB Decision Logics• Round Robin• Static Proximity• Source IP Hash• Dynamic Proximity {RTT}• Least methods • Connections • Packets • Bandwidth • Response © 2007 Citrix Systems, Inc. — All rights reserved 15
  • GSLB Decision Logics: Weighted LoadBalancing• Sites may have different infrastructure (Quantity and Capacity of Servers, bandwidth, etc)• GSLB will send DNS responses in the ratio of weights associated with sites• Site weight can be calculated dynamically by making it proportional to back end service count or weight © 2007 Citrix Systems, Inc. — All rights reserved 16
  • GSLB Decision Logics: Policy Based • Bypass the configured site selection algorithm • User defined qualifying expressions • Define policies and actions • Even though LDNS is geographically closer to site-1, point to site-2, where the servers are less loaded than site-1 • Site Affinity via GSLB Policies • Evaluation of attributes on incoming client LDNS requests to conditionally direct clients to a specific GSLB site • Requires content filtering be enabled • Always globally applied in GSLB © 2007 Citrix Systems, Inc. — All rights reserved 17
  • GSLB Decision Logics:Proximity Methods• Allows for faster response resulting from selection of the closest available site • Dynamic Network Proximity (RTT) • Determine site to send client to based on client’s local DNS (LDNS) proximity to various sites • Gauged by Round Trip Time to the LDNS host • RTT tolerance factor, LDNS mask & entry timeout used to modify RTT further • Static Proximity • Determine site to direct client to based on proximity to geographic locations in a static location database • Use location commands in configuring and populating the location DB• Proximity methods require a specific license © 2007 Citrix Systems, Inc. — All rights reserved 18
  • GSLB Decision Logics: Persistence • Site Persistence • Ensure LDNS requests are sent the same site and not load balanced • Source IP persistence set with: > set gslb vserver gslbvip -persistenceType SOURCEIP –persistenceID <positive_integer> • Cookie based persistence and connection proxy • Allows setting HTTP level persistence • Configured on local gslb services with options: -SitePersistence ConnectionProxy -cookieTimeout <integer> -CIP ENABLED <cipheader> © 2007 Citrix Systems, Inc. — All rights reserved 19
  • AgendaGSLB OverviewGSLB OperationDecision LogicsConfigurationDemonstration © 2007 Citrix Systems, Inc. — All rights reserved 20
  • Configuration StepsSteps for Basic Configuration via CLI 1. Create GSLB sites > add gslb site siteA LOCAL 172.22.8.10 > add gslb site siteB REMOTE 172.22.8.11 note: If you want them to use secure connections you must enable this after you add the sites set ns rpcNode <ip_addr> -secure yes 2. Configure LoadBalancing > add lb vserver vs1 http 172.22.8.200 > add service svc1 192.168.10.25 http 80 > bind lb vserver vs1 svc1 © 2007 Citrix Systems, Inc. — All rights reserved 21
  • Configuration Steps con’t 3. Configure GSLB Load Balancing > add server GSLB_SRV1 172.22.8.200 > add server GSLB_RMT1 172.22.8.100 > add gslb vserver GSLB_VS1 http –lbmethod ROUNDROBIN > add gslb service GSLB_SVC1 172.22.8.200 http 80 – siteName siteA > add gslb service GSLB_RMT1 172.22.8.100 http 80 – siteName siteB > bind gslb vserver GSLB_VS1 -serviceName GSLB_RMT1 > bind gslb vserver GSLB_VS1 -serviceName GSLB_SVC1 > bind gslb vserver GSLB_VS1 -domainName www.testlab.com -TTL 5 Once all sites, vservers, services are reported as up, tailor DNS, GSLB methods, persistence, and site affinity as necessary © 2007 Citrix Systems, Inc. — All rights reserved 22
  • Configuring DNS: ADNS1. Set up each NetScaler site as an SOA: > add service gslb_adns_svc 172.22.8.205 adns 53 > add dns soarec www.testlab.com –originServer www.testlab.com –contact noc.testlab.com –serial 1 –refresh 300 –retry 600 – expire 604800 –minimum 3600 – ttl 3600Repeat on each site with corresponding site values2. Add DNS records for required addresses within the domain > add dns addrec sitea.testlab.com 172.22.8.10 > add dns addrec siteb.testlab.com 172.22.8.11 Duplicate records on the other sites © 2007 Citrix Systems, Inc. — All rights reserved 23
  • Configuring DNS: ProxyEnable the NetScaler to query a backend DNS server1. Create a DNS vserver:> add vserver dns_vip dns 172.22.8.2052. Add DNS service:> add dns_svc 192.168.10.10 dns 533. Bind the two:> bind lb vserver dns_vip dns_svcNote: With vserver type DNS we will cache responses for TTL. To disable this use “set dns parameter -cacheRecords NO” © 2007 Citrix Systems, Inc. — All rights reserved 24
  • GSLB GUI © 2007 Citrix Systems, Inc. — All rights reserved 25
  • GSLB GUI con’t © 2007 Citrix Systems, Inc. — All rights reserved 26
  • Adding a Server © 2007 Citrix Systems, Inc. — All rights reserved 27
  • Add GSLB Service © 2007 Citrix Systems, Inc. — All rights reserved 28
  • Add GSLB Service con’t © 2007 Citrix Systems, Inc. — All rights reserved 29
  • Add GSLB Vserver © 2007 Citrix Systems, Inc. — All rights reserved 30
  • Add GSLB Vserver con’t © 2007 Citrix Systems, Inc. — All rights reserved 31
  • Add GSLB Vserver con’t © 2007 Citrix Systems, Inc. — All rights reserved 32
  • Add GSLB Vserver con’t © 2007 Citrix Systems, Inc. — All rights reserved 33
  • Secure Option >set ns rpcNode 172.22.8.21 -secure YES © 2007 Citrix Systems, Inc. — All rights reserved 34
  • DNS Records > flush dns proxyRecords © 2007 Citrix Systems, Inc. — All rights reserved 35
  • DNS Records © 2007 Citrix Systems, Inc. — All rights reserved 36
  • DNS Views © 2007 Citrix Systems, Inc. — All rights reserved 37
  • DNS Views © 2007 Citrix Systems, Inc. — All rights reserved 38
  • DNS Views con’t © 2007 Citrix Systems, Inc. — All rights reserved 39
  • DNS Views © 2007 Citrix Systems, Inc. — All rights reserved 40
  • DNS Views con’t © 2007 Citrix Systems, Inc. — All rights reserved 41
  • AgendaGSLB OverviewGSLB OperationDecision LogicsConfigurationDemonstration © 2007 Citrix Systems, Inc. — All rights reserved 42
  • Demonstration• Active-Active configuration • NetScaler will server IP from two active sites in round robin fashion.• Active-Standby configuration • NetScaler will server IP from SITEA only unless SITEA goes down then the IP from SITEB will be served.• Static Proximity • NS will hand out IP based on SRCIP of the request © 2007 Citrix Systems, Inc. — All rights reserved 43