Table Of Contents
Configuring the DNS Sticky Feature
DNS Sticky in a Network Proximity Environment
DNS Sticky Quick-Start Procedures
Configuring DNS Sticky without a GSDB
Configuring DNS Sticky with a GSDB
Global Sticky Database Configuration Quick Start
DNS Server Configuration Quick Start
Configuring DNS Sticky with Network Proximity
Global Sticky Database Configuration Quick Start
DNS Server Configuration Quickstart
Converting Content Rule-Based DNS to Zone-Based DNS
Configuring DNS Sticky Parameters
Enabling the Global Sticky Database
Resetting the Global Sticky Database Statistics
Configuring the Global Sticky Database Interface
Resetting the Global Sticky Database Interface Statistics
Configuring the Time to Live for Global Sticky Database Entries
Configuring Sticky Domain Records
Configuring Server Zones for DNS Sticky
Displaying DNS Sticky Statistics
Displaying Global Sticky Database Statistics
Displaying GSDB Interface Statistics
Displaying DNS Sticky Domain Record Statistics
Displaying Domain Load Statistics
Displaying DNS Record Statistics
Displaying DNS Record Keepalives
Displaying Proximity and GSDB Metrics
Displaying Server Zones for DNS Sticky
Configuring the DNS Sticky Feature
This chapter provides an overview of the CSS Domain Name System (DNS) Sticky feature and describes how to configure it for operation. Information in this chapter applies to all CSS models, except where noted.
Note
The DNS Sticky feature requires the CSS Enhanced feature set license.
This chapter provides the following major sections:
•
•
•
•
Overview of DNS Sticky
Configure DNS Sticky on a CSS to ensure that e-commerce clients remain connected to a particular server for the duration of a transaction even when the client's browser refreshes the DNS mapping. While some browsers allow client connections to remain for the lifetime of the browser instance or for several hours, other browsers impose a connection limit of 30 minutes before requiring a DNS re-resolution. This may not be long enough for a client to complete an e-commerce transaction. A new DNS resolution could cause the client to connect to a server different from the original server and interrupt the transaction. DNS Sticky ensures that a client can complete a transaction if a DNS re-resolution occurs.
DNS Sticky extends the functionality of global server load balancing (GSLB) and Network Proximity by providing:
•
•
•
You can configure DNS Sticky in three different environments, depending on your current configuration and business needs as follows:
•
DNS Sticky Without a GSDB
DNS Sticky without a GSDB in a GSLB environment provides a static, simple, and cost-effective solution to the DNS sticky problem. This solution:
•
•
•
•
In a GSLB sticky configuration without a GSDB, the CSS configured as an authoritative DNS server selects a server for a sticky domain request based on the srcip hash (regardless of the default load-balancing method) and the availability of the domain in the zone mesh. The use of the srcip hash ensures that the CSS selects a consistent zone for a given source IP address.
DNS Sticky with a GSDB
DNS Sticky with a GSDB in a GSLB environment provides a more robust sticky load-balancing solution than one without a GSDB. This solution includes all of the benefits of DNS Sticky without a GSDB, plus:
•
•
•
Note
In a GSLB sticky configuration with a GSDB, a CSS configured as an authoritative DNS server sends a lookup request to the GSDB for a sticky domain requested by a client. If the GSDB finds an entry for the client's local DNS server IP address in its sticky database, it returns the sticky zone index to the CSS. The CSS uses the sticky zone index and keepalive information to send the appropriate IP address to the client. If the GSDB does not have an entry for the client's local DNS server IP address or the zone in the sticky zone index returned by the GSDB is unavailable, the CSS selects a zone in the mesh based on the configured load-balancing method and informs the GSDB about the selected zone.
Note
DNS Sticky in a Network Proximity Environment
Configure DNS Sticky in a Network Proximity environment to add stickiness to your network. This solution adds all the benefits of DNS Sticky with a GSDB to your existing proximity configuration. In this case, you can specify critical e-commerce sites as sticky domains and use proximity for your other domains.
In a Network Proximity environment, you configure a GSDB on the CSS configured as a Proximity Database (PDB) and at least one GSDB interface on the Proximity Domain Name Server (PDNS) in each zone. The IP address of the primary GSDB interface is typically the same as the PDB IP address. In addition, you configure sticky domain records using the dns-record command.
When a CSS configured as a PDNS receives a client request for a sticky domain, the PDNS first consults the GSDB. If a sticky database entry exists for the client's local DNS server IP address, the PDNS sends the appropriate IP address to the client based on the zone index returned by the GSDB. If a sticky database entry does not exist for the client's local DNS server IP address, the PDNS consults the PDB for a Proximity-based answer. The PDNS formulates a response to the client based on the ordered zone index returned by the PDB and keepalive information. The PDNS informs the GSDB about the selected zone.
If neither the GSDB nor the PDB returns a suitable response, the PDNS selects a zone based on its configured default load-balancing method to formulate an appropriate response to the client and informs the GSDB about the selected zone.
For details on configuring Network Proximity, see Chapter 5, Configuring Network Proximity.
DNS Sticky Quick-Start Procedures
The following sections provide the procedures required to configure DNS Sticky on a CSS.
Configuring DNS Sticky without a GSDB
Table 2-1 provides a quick overview of the steps required to configure DNS Sticky on a CSS without a GSDB. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the DNS Sticky commands later in this chapter.
Table 2-1 DNS Sticky Without a GSDB Configuration Quick Start
1.
# config (config)#2.
(config)# app3.
(config)# dns-server zone 0 tier1 "usa"4.
(config)# app session 172.27.16.55.
(config)# dns-record a www.home.com 192.168.1.5 15 single kal-ap 172.27.25.4 50 sticky-enabled(config)# dns-record ns www.work.com 192.168.12.7 15 single kal-ap 172.27.33.3 100 default sticky-enabled6.
(config)# dns-server
The following running-config example shows the results of entering the commands described in Table 2-2.
!*************************** GLOBAL ***************************dns-server zone 0 tier1 "usa"dns-record a www.home.com 192.168.1.5 15 single kal-ap 172.27.25.4 50 sticky-enableddns-record ns www.work.com 192.168.12.7 15 single kal-ap 172.27.33.3 100 default sticky-enableddns-serverappapp session 172.27.16.5Configuring DNS Sticky with a GSDB
The following sections describe the steps required to configure DNS Sticky with a GSDB. You can configure the GSDB and the DNS server in any order.
Global Sticky Database Configuration Quick Start
Table 2-2 provides a quick overview of the steps required to configure the GSDB on a CSS. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the DNS Sticky commands later in this chapter.
Table 2-2 Global Sticky Database Configuration Quick Start
1.
# config (config)#2.
(config)# app-udp3.
(config)# app4.
(config)# app session 172.27.16.35.
(config)# proximity db 0 tier1 "usa"6.
(config)# gsdb7.
(config)# gsdb ttl 14400
The following running-config example shows the results of entering the commands described in Table 2-2.
!*************************** GLOBAL ***************************app-udpproximity db 0 tier1 "usa"gsdbgsdb ttl 14400appapp session 172.27.16.3DNS Server Configuration Quick Start
Table 2-3 provides a quick overview of the steps required to configure the DNS Sticky feature on a CSS acting as an authoritative DNS server and using a GSDB. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the DNS Sticky commands later in this chapter.
Table 2-3 DNS Server Configuration Quick Start
1.
# config (config)#2.
(config)# app-udp3.
(config)# app4.
(config)# gsdb-interface primary 192.168.68.12(config)# gsdb-interface secondary 192.168.68.135.
(config)# dns-server zone 0 tier1 "usa"6.
(config)# dns-server7.
(config)# app session 172.27.16.58.
(config)# dns-record a www.home.com 192.168.1.1 15 single kal-ap 172.27.25.4 50 sticky-enabled(config)# dns-record ns www.work.com 192.172.12.1 15 single kal-ap 172.27.33.3 100 default sticky-enabled
The following running-config example shows the results of entering the commands described in Table 2-3.
!*************************** GLOBAL ***************************app-udpdns-server zone 0 tier1 "usa"dns-record a www.home.com 192.168.1.1 15 single kal-ap 172.27.25.4 50 sticky-enableddns-record ns www.work.com 192.168.12.1 15 single kal-ap 172.27.33.3 100 default sticky-enabledgsdb-interface primary 192.168.68.12gsdb-interface secondary 192.168.68.13dns-serverappapp session 172.27.16.5Configuring DNS Sticky with Network Proximity
The following sections describe the steps required to configure DNS Sticky in an existing Network Proximity configuration. For details on configuring Network Proximity, see Chapter 5, Configuring Network Proximity.
Global Sticky Database Configuration Quick Start
Table 2-4 provides a quick overview of the steps required to configure the GSDB on a PDB. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the DNS Sticky commands later in this chapter.
DNS Server Configuration Quickstart
Table 2-5 provides a quick overview of the steps required to configure the DNS Sticky feature on a PDNS. Each step includes the CLI command required to complete the task. For a complete description of each feature and all the options associated with the CLI commands, see the DNS Sticky commands later in this chapter.
Table 2-5 DNS Server Configuration Quick Start
1.
# config (config)#2.
(config)# gsdb-interface primary 192.168.68.1(config)# gsdb-interface secondary 192.168.68.23.
(config)# dns-record a www.home.com 192.168.1.1 15 single kal-ap 172.68.25.1 50 sticky-enabled(config)# dns-record ns www.work.com 192.168.12.1 15 single kal-ap 172.92.33.1 100 default sticky-enabled
Converting Content Rule-Based DNS to Zone-Based DNS
DNS Sticky requires a zone-based DNS configuration. If you currently have a content rule-based DNS configuration, use the following procedure to convert your DNS configuration to a zone-based DNS configuration.
1.
(config)# no dns-peer interval(config)# no dns-peer receive-slots(config)# no dns-peer send-slots(config-owner)# no dns(config-owner-content)# remove dns(config-owner-content)# no dns-balance2.
Note the following:
•
•
•
3.
For example, suppose you have the following owner configuration.
!*************************** OWNER ***************************owner GLBcontent rule1add service s1vip address 5.5.5.5add dns www.work.comactiveYou would need to add a record similar to the following.
(config)# dns-record a www.work.com 5.5.5.5 0 single kal-ap 1.1.1.1For details on configuring zone-based DNS, see the "Configuring a DNS Server" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
For details on configuring content rule-based DNS, see the "Configuring Content Rule-Based DNS on a CSS" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
Configuring DNS Sticky Parameters
The following sections describe the commands and their options and variables that you use to configure DNS Sticky.
Enabling the Global Sticky Database
The global sticky database comprises:
•
•
•
The sticky zone index contains a listing of configured sticky zones and IP addresses. If the GSDB has an entry for the requesting client's local DNS server, the GSDB sends the sticky zone index to the CSS DNS server that made the GSDB lookup request. The CSS uses the sticky zone index and keepalive information to select the appropriate sticky zone and sends the IP address of the zone to the client's local DNS server.
Note
To enable a GSDB on a dedicated CSS 11150 with 256 MB of RAM when you are configuring GSLB with a GSDB (see "DNS Sticky with a GSDB" earlier in this chapter) or when you are using DNS Sticky in a Network Proximity configuration (see "DNS Sticky in a Network Proximity Environment" earlier in this chapter), use the gsdb command.
Note
Note
The syntax for this global configuration mode command is:
gsdb
To disable a GSDB, enter:
(config)# no gsdbResetting the Global Sticky Database Statistics
Use the gsdb zero command to reset the Sticky Lookups and Sticky Sets statistics that are displayed by the show gsdb command. The syntax for this global configuration mode command is:
gsdb zero
Configuring the Global Sticky Database Interface
Use the gsdb-interface command on the CSS DNS server to create an interface for the CSS to communicate with a GSDB. A GSDB responds with a zone index to sticky queries from CSS DNS servers. All GSDBs participating in a peer mesh share sticky TTL and sticky zone information over APP.
Note
The syntax for this global configuration mode command is:
gsdb-interface [primary|secondary] ip_address
The variables and options are:
•
•
Note
For example:
(config)# gsdb-interface primary 192.168.11.1To delete a primary GSDB interface, enter:
(config)# no gsdb-interface primaryResetting the Global Sticky Database Interface Statistics
Use the gsdb-interface zero command to reset the GSDB interface statistics that are displayed by the show gsdb-interface command. The syntax for this global configuration mode command is:
gsdb-interface zero
Configuring the Time to Live for Global Sticky Database Entries
Issue the gsdb ttl command on the GSDB to specify a time to live (TTL) for the GSDB sticky domain entries. The value you enter determines the length of time in seconds that GSDB entries are valid. Any new request from a D-proxy for a sticky domain that arrives before the timer expires, resets the timer.
The syntax for this global configuration mode command is:
gsdb ttl ttl_value
The variable is ttl_value, which specifies the length of time in seconds that GSDB entries are valid. Enter an integer between 300 and 1000000. The default is 7200 seconds (2 hours).
For example:
(config)# gsdb ttl 7200Configuring Sticky Domain Records
Use the dns-record command to configure sticky domain records on the CSS configured as a DNS server. Domain records labeled as sticky-enabled indicate to the CSS that it should attempt to provide a sticky response before it answers the DNS query from the client.
Note
For details on configuring domain records, see the "Configuring Domain Records" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
Configuring Server Zones for DNS Sticky
Use the dns-server zone command to configure DNS server zones in the CSS. This feature allows the CSS to respond to DNS requests based upon different balance criteria and domain availability within zones or locations. For details on configuring zones, see the "Configuring DNS Server Zones" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
Displaying DNS Sticky Statistics
To display DNS Sticky statistics for the GSDB, GSDB interface, domain records, and DNS server zones, use the show commands in this section.
Displaying Global Sticky Database Statistics
Use the show gsdb command to display GSDB statistics. This command is part of the PDB feature set and is available in all modes. The syntax is:
show gsdb
Table 2-6 describes the fields in the show gsdb output.
Displaying GSDB Interface Statistics
Use the show gsdb-interface command to display statistics for the GSDB interface on the DNS server CSS. This command is part of the Enhanced feature set and is available in all modes.
Note
The syntax is:
show gsdb-interface
Table 2-7 describes the fields in the show gsdb-interface output.
Displaying DNS Sticky Domain Record Statistics
Use the show dns-record sticky command to view statistics associated with sticky domain records. This command is part of the Enhanced feature set and is available in all modes. The syntax is:
show dns-record sticky {dns_name}
The variable is dns_name, which is the DNS name mapped to a domain record for which you want to display sticky domain statistics. Enter the name as a lower case unquoted text string with no spaces and a maximum of 63 characters.
Table 2-8 describes the fields in the show dns-record sticky output.
Displaying Domain Load Statistics
Use the show dns-record load command to display load information associated with domains. The syntax for this all configuration mode command is:
show dns-record load {dns_name}
The variable is dns_name, which is the DNS name mapped to a domain record for which you want to display load statistics. Enter the name as a lower case unquoted text string with no spaces and a maximum of 63 characters.
Table 2-9 describes the fields in the show dns-record load output.
Displaying DNS Record Statistics
Use the show dns-record statistics command to display statistics associated with the domain records configured locally and learned by the CSS from its peers. For details on displaying DNS record statistics, see the "Displaying DNS Record Information" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
Displaying DNS Record Keepalives
Use the show dns-record keepalive command to display information about keepalives associated with DNS records. For details on displaying DNS record keepalives, see the "Displaying DNS Record Keepalive Information" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
Displaying Proximity and GSDB Metrics
Use the show proximity metric command to display GSDB and/or PDB metrics (in milliseconds) associated with a client's local DNS server IP address. This command is available on a GSDB, a PDB, and a PDNS.
The syntax for this global configuration mode command is:
show proximity metric ip_address {ip_prefix {aggregate}}
The variables and options are:
•
•
–
–
•
Note
In the GSDB, the metrics are sorted by sticky zone index. In the PDB, the round-trip time (RTT) metrics are sorted by proximity zone. In the PDNS, the metrics are sorted by RTT. An asterisk next to a zone indicates the local zone where the command was issued.
Note
For example, to view the PDB and /or GSDB metrics associated with the client IP address of 172.23.5.7 and an IP prefix of 24, enter:
(config)# show proximity metric 172.23.5.7/24Table 2-10 describes the fields in the show proximity metric output.
Displaying Server Zones for DNS Sticky
Use the show zone command to display information about DNS server zones communicating in a zone mesh. For details on displaying DNS server zones, see the "Displaying DNS Server Zones" section in Chapter 1, Configuring the CSS as a Domain Name System Server.
