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January 2012
ServerIron ADX
Global Server Load Balancing Guide
Supporting Brocade ServerIron ADX version 12.4.00
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© 2012 Brocade Communications Systems, Inc. All Rights Reserved. Brocade, the B-wing symbol, BigIron, DCFM, DCX, Fabric OS, FastIron, IronView, NetIron, SAN Health, ServerIron, TurboIron, and Wingspan are registered trademarks, and Brocade Assurance, Brocade NET Health, Brocade One, Extraordinary Networks, MyBrocade, VCS, and VDX are trademarks of Brocade Communications Systems, Inc., in the United States and/or in other countries. Other brands, products, or service names mentioned are or ma
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Contents About This Document Audience . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Supported hardware and software . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Document conventions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Text formatting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ix Notes, cautions, and danger notices . . . . . . . . . . . . . . . . . . . . . .
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Site persistence in GSLB using stickiness. . . . . . . . . . . . . . . . . . . . .64 Algorithm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65 Enabling sticky GSLB . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66 Allowing sticky sessions for a specific prefix length . . . . . . . . .67 Configuring the sticky GSLB session life time . . . . . . . . . . . . . .67 Displaying current sticky GSLB sessions . . . . . . . . . . . . . . . . . .6
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DNSSEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .112 Verification with DIG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .114 DNSSEC GSLB in DNS proxy mode . . . . . . . . . . . . . . . . . . . . . .114 Configuring DNSSEC for GSLB . . . . . . . . . . . . . . . . . . . . . . . . .115 Displaying DNSSEC configuration. . . . . . . . . . . . . . . . . . . . . . .116 Displaying DNSSEC statistics . . . . . . . . . . . . . . . . . . .
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Displaying GSLB information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165 Displaying site information . . . . . . . . . . . . . . . . . . . . . . . . . . . .165 Displaying real server information . . . . . . . . . . . . . . . . . . . . . .168 Displaying DNS zone and hosts . . . . . . . . . . . . . . . . . . . . . . . .170 Displaying metric information . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Displaying the default GSLB policy . . . . . . . . . . . . . . . . . . .
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Displaying GSLB for IPv6 configurations . . . . . . . . . . . . . . . . . . . . .231 Show commands for basic GSLB configurations. . . . . . . . . . .231 Show commands for advanced features . . . . . . . . . . . . . . . . .245 Troubleshooting GSLB for IPv6 configurations . . . . . . . . . . . . . . . .246 Appendix A Reference Materials RFC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251 IPv4 . . . . . . . . . . . . . . . . . . . . . . . . .
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viii ServerIron ADX Global Server Load Balancing Guide 53-1002437-01
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About This Document Audience This document is designed for system administrators with a working knowledge of Layer 2 and Layer 3 switching and routing. If you are using a Brocade Layer 3 Switch, you should be familiar with the following protocols if applicable to your network – IP, RIP, OSPF, BGP, ISIS, IGMP, PIM, DVMRP, and VRRP. Supported hardware and software Although many different software and hardware configurations are tested and supported by Brocade Communications Systems, Inc. for 1
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bold text Identifies command names Identifies the names of user-manipulated GUI elements Identifies keywords Identifies text to enter at the GUI or CLI italic text Provides emphasis Identifies variables Identifies document titles code text Identifies CLI output For readability, command names in the narrative portions of this guide are presented in bold: for example, show version. Notes, cautions, and danger notices The following notices and statements are used in this manual. They are listed be
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Corporation Referenced Trademarks and Products Microsoft Corporation Windows NT, Windows 2000 The Open Group Linux Related publications The following Brocade documents supplement the information in this guide: • Release Notes for ServerIron Switch and Router Software TrafficWorks 12.2.00 • ServerIron ADX Graphical User Interface • ServerIron ADX Server Load Balancing Guide • ServerIron ADX Advanced Server Load Balancing Guide • ServerIron ADX Global Server Load Balancing Guide • ServerIron ADX
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Chapter Global Server Load Balancing 1 Global Server Load Balancing overview Global Server Load Balancing (GSLB) enables a ServerIron ADX to add intelligence to authoritative Domain Name System (DNS) servers by serving as a proxy to these servers and providing optimal IP addresses to the querying clients. As a DNS proxy, the GSLB ServerIron ADX evaluates the IP addresses in the DNS replies from the authoritative DNS server for which the ServerIron ADX is a proxy and places the “best” host ad
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1 Global Server Load Balancing overview If the local DNS server does not have an address record for the requested server, the local DNS server makes a recursive query. When a request reaches an authoritative DNS server, that DNS server responds to this DNS query. The client’s local DNS server then sends the reply to the client. The client now can access the requested host. With the introduction of redundant servers, a domain name can reside at multiple sites, with different IP addresses. Wh
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Global Server Load Balancing overview 1 • Session table statistics and CPU load information — The site ServerIron ADXs report this information to the GSLB ServerIron ADX at regular intervals. By default, each remote ServerIron ADX sends the status information to the GSLB ServerIron ADX every 30 seconds. You can change the update period for all the remote ServerIron ADXs by specifying a new period on the GSLB ServerIron ADX if needed. • RTT — Round Trip Time (RTT) is the amount of time that
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1 Global Server Load Balancing overview • IMAP4: the well-known name for port 143 • LDAP: the well-known name for port 389 • NNTP: the well-known name for port 119 • POP3: the well-known name for port 110 • SMTP: the well-known name for port 25 • TELNET: the well-known name for port 23 NOTE To display the list when configuring zone information, enter the host-info ? command, where is a string specifying a host name. For other applications (applications not listed above),
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Global Server Load Balancing overview 1 3. The authoritative DNS server for brocade.com answers the client’s query (forwarded by the GSLB ServerIron) by sending a list of IP addresses for the sites that correspond to the requested host. GSLB Site 1 Authoritative DNS server Sunnyvale 4. The GSLB ServerIron assesses each for domain brocade.com IP address in the DNS reply to determine the optimal site for the client, slb1: 209.157.22.209 209.157.23.46 and moves the address for that site to DNS the
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1 Global Server Load Balancing overview servers that receive the records retain them in their databases for only 10 seconds. After the ten seconds expire, subsequent requests from the client initiate another query to the authoritative DNS server. As a result, the client always receives fresh information and the address of the site that is truly the best site for the client. NOTE You also can change the TTL if needed. However, Brocade recommends that you do not change the TTL to 0, because
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Global Server Load Balancing overview 1 If the GSLB policy rejects all of the sites, the GSLB ServerIron ADX sends the DNS reply unchanged to the client. All of these metrics have default values but you can change the values if needed. In addition, you can disable individual metrics or reorder them. Refer to “Changing the GSLB policy metrics” on page 34. You also can configure the GSLB ServerIron ADX to directly respond to DNS queries instead of forwarding the queries to the authoritative DN
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1 Global Server Load Balancing overview NOTE You cannot use the weighted IP metric if the weighted site metric is enabled. The GSLB ServerIron ADX uses relative percentages in order to achieve 100% total weight distribution. To configure weighted IP metrics, refer to “Implementing the weighted IP metric” on page 40. Weighted site metric You can configure the ServerIron ADX to distribute SLB traffic among GSLB sites based on weights configured for the sites. The weights determine the percentage
