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Deploying Global Server Load Balancing. Using Persistent Methods. Sam Cohoon. May 21, 2013. Global Server Load Balancing. Global Server Load Balancing. Global Server Load Balancing. What is GSLB?. DNS.
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Deploying Global Server Load Balancing Using Persistent Methods Sam Cohoon May 21, 2013
DNS The Citrix NetScaler implementation of Global Server Load Balancing GSLB is Domain Name System (DNS) based.
How it works - Summary DNS and MEP Components: GSLB domain, GSLB site, GSLB vserver, GSLB service
GSLB Configuration Where do I start?
Synchronizing Configuration 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.
GSLB Load Balancing methods The NetScaler GSLB methods: Round Trip Time (RTT) Static Proximity
Local DNS IP (LDNS) 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.
GSLB Static Proximity IP-address based static proximity database is a UNIX-based ASCII file.
GSLB Static Proximity Troubleshooting nsmap -t –d root@test# nsmap -t -d Enter IP address to to test (dot notation) or q to exit:
GSLB Static Proximity Troubleshooting > show locationparameter Static Proximity ---------------- Database mode: Not applicable Flushing: Idle; Loading: Idle Context: geographic Qualifier 1 label: Continent Qualifier 2 label: Country Qualifier 3 label: Region Qualifier 4 label: City Qualifier 5 label: ISP Qualifier 6 label: Organization Location file (format: Not applicable): Not loaded Lines: 0 Warnings: 0 Errors: 0 Current static entries: 0 Current custom entries: 0 Done
GSLB Dynamic RTT Dynamic RTT : measure from each “site” NetScaler to the remote LDNS Three Monitors: Ping of IP address (LDNS-PING) DNS TCP probe DNS UDP query
Global Server Load Balancing Persistence
Persistence Based on Source IP 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.
Global Server Load Balancing HTTP Cookie Persistence
Persistence Based on HTTP Cookies HTTP-request level Connection proxy HTTP redirect.
HTTP Connection Proxy 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
HTTP Redirect Persistence Redirect persistence can be used only: For HTTP or HTTPS protocols. If the domain name in the request is a GSLB Domain When a backup VIP or a GSLB local service is DOWN
Global Server Load Balancing Troubleshooting
GSLB Troubleshooting > 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
GSLB Troubleshooting > 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
GSLB Troubleshooting > sh gslb service 1) 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
GSLB Troubleshooting root@ns# nsconmsg -K newnslog -d stats | grep gslb root@ns# nsconmsg -g glsb -d current -s disptime=1
Resources 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