HP sa9200 User Manual

hp multi-site traffic director server appliance

sa9200

user guide

Hewlett-Packard Company 3000 Hanover Street Palo Alto, CA 94304-1185

Publication Number

5971-0897 March 2001

Disclaimer

The information containe d in thi s do cum e nt is subjec t to chan ge without no tic e .

HEWLETT-PACKARD COMPANY MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Hewlett-Packard shall not be liable for errors contained herein or f or incidental or conse quential damages in connection with the furnishing, performance, or use of this material.

Hewlett-Packard assumes no responsibility for the use or reliability of its software on equipment that is not furnished by Hewlett-Packard.

Warranty

A copy of the specific warranty terms applicable to your Hewlett-Packard products and replacement parts can be obtained from http://www.hp.com/serverappliances/support.

*Other brands and names are the prop erty of their respective owners.

Chapter 1: Introduction 1

What is an HP Multi-Site Traffic Director Server Appliance SA9200? . . . . . . . . . . . 1

Who Should Use This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

User Guide Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Chapter 2: Theory of Operations 5

Site Balancing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

“Intelligent” DNS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Traditional DNS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Authoritative DNS Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Multi-Site Traffic Management Using HP Traffic Directors . . . . . . . . . . . . . . . . . . . 8

Multi-Site Traffic Management Without HP Traffic Directors . . . . . . . . . . . . . . . 9

Typical Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Site Balancing Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Weighted Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Metric Algorithms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Flash DNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Partial Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Multiple VIP Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

C O N T E N T S HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Chapter 3: CLI Configuratio n 17

Custom/Manual Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Command Line Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Adding a Secondary SA9200. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Creating Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Associating Services with Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Creating Zones. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Creating Authority Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Creating Hosts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Committing the Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

NSLookup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Configure DNS Servers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Multiple-VIP Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Chapter 4: Multi-Site Scenarios 25

Scenario 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Part 1 – Initial Configuration of a Simple Site. . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Part 2 – Changing to Flash Response Mode Balancing. . . . . . . . . . . . . . . . . . . . . 32

Part 3 – Adding Load Balancers to an Existing Site . . . . . . . . . . . . . . . . . . . . . . . 33

Scenario 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Configuring in a Mixed Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Chapter 5: Boot Monitor 55

System Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Accessing the Boot Monitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Boot Monitor Command Reference. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Chapter 6: CLI Reference 67

Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Editing the Command Line . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Command History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Pipes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Online Help . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Command Line Syntax. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71

CLI Command Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Contents

Objects and Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72

Global & CLI System Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

File Management Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Configuration Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

System Commands. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95

DNS Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Show Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132

Chapter 7: SNMP Support 149

Standards Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

HP MIB Tree . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150

Supported MIBs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Where to find MIB Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

Agent Metrics Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152

Service Metrics Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153

ISV Metrics Group. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154

Site Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

SNMP Traps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155

Configuring Trap Parameters. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157

Configuring Community Authentication & Security Parameters . . . . . . . . . . . . . . 157

Configuring Other SNMP Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158

Chapter 8: Software Updates 161

Multiple Software Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

Software Image Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161

Saving Your Current Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Downloading and Installing the Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162

Rebooting with the New Image and Verifying Installation . . . . . . . . . . . . . . . . . . 163

Restoring Your Previous Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

Appendix A: Diagnostics 165

Appendix B: Cleaning the Dust Filter 173

Appendix C: Regulatory Information 175

iii

C O N T E N T S HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Appendix D: Terms, Conditions and Software License 187

Support Services 189

Glossary 193

Index 197

Introduction

What is an HP Multi-Site Traffic Director Server Appliance SA9200?

The HP Multi-Site Traffic Director Server Appliance SA9200 is a global site balancer. It gathers your geographically dispersed data sites into multiple “virtual servers,” which gives you multifaceted, centralized control over widely distributed resources.

• Performance

The SA9200 looks at individual client requests and mat ches them up with the best of many geographically dispersed fulfillment sites using the selection method most appropriate to your speci fic needs.

• Reliability

The SA9200 supports active-active redundant mode, meaning that multiple, active S A9200 s can be used simultaneously. When one fails, any remaining SA9200s continue operation.

C H A P T E R 1 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

• Scalability

The SA9200 can work cooperatively with up to fifteen other SA9200s in deployment across sites. A site may be managed by any HP Traffic Director Server Appliance or HP e-Commerce Traffic Director Serv er Appliance, which can in turn intelligen tly manage server farms, and return server performance data to the SA9200. The SA9200 also supports sites that have third-party load balancers.

• Flexibility

The SA9200 offers six distinct methods of balancing your distributed resources, ensuring a solution for your multi-site problems.

• Weighted Round Robin

• Weighted Random

• Response Time

• Least Connections

• CPU Utilization of Local Load Balancer

• Flash DNS

Who Should Use This Book

This user guide is intended for network administrators with a basic knowledge of:

• Networking concepts and terminology

• Network topologies

• IP routing

• DNS and BIND

C H A P T E R 1 User Guide Summary

User Guide Summary

In addition to this int roduction , the user guide co ntains the followi ng chapters:

• Theory of Operations

An overview of the multi-site network, the SA9200’s place in it, and some concepts you need to know to use the unit effectively.

• CLI Configuration

Instructions on how to use the Command Line Interface (CLI) to manually configure additional sites, agents, zones, and services.

• Multi-Site Scenar ios

Descriptions of several typical multi-site challenges accompanied by their corresponding SA9200 solutions.

• Boot Monitor

An explanation and reference of the SA9200’s configuration commands.

• CLI Reference

Detailed descriptions of the SA9200’s operational commands, including tree illustrations of the command system structure.

• SNMP Suppor t

Details of SA9200’s SNMP capabilities.

• Software Updates

Software update procedures.

• Diagnostics (Appendix A)

How to interpret the SA 9200’s LED display.

• Cleaning the Dust Filter (Appendix B)

• Regulatory Information (Append ix C)

• Terms, Conditions and Software License (Appendix D)

End user terms, conditions, and licensing information.

• Support Services

• Glossary

• Index

C H A P T E R 1 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Notes

Theory of Operations

NOTE: HP Traffic Director refers to either an HP Traffic Director Server Appliance, Model SA7200 and SA7220; or HP e-Commerce Director Server Appliance, Model s SA8200 and SA8220.

Typical load balancers work by balancing traffic over a Local Area Network (LAN) to a Web farm. The HP Multi-Site Traffic Directo r Server Appliance SA9200 extends this balancing to multiple sites over a Wide Area Network (WAN). By balancing referrals to each site, the SA9200 enables enterprises and Web hosting services to integrate geographically distributed content and services.

The advantages of such integration are many, including:

• There is increased fault tolerance and availability owing to

redundant sites . Multiple ac tive sites per mit uninterr upted servic e in the event of a localized outage in the data network.

• Customer response times are improved by directing users to

uncongested sites or data centers.

• Easy scaling of server farms can be accomplished.

Multi-site load balancin g works best in concert with HP Traffic Directors. The SA9200 also supports multi-site load balancing with sites that do not have HP Traffic Directors. In this case, the sites are balanced on the basis of availability, and not based on proprietary metric information.

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Site Balancing

“Intelligent” DNS

Traditional DNS

The SA9200 leverages the DNS architectu re and protocol as the basis for its site balancing op erations. Based on the information gathered from all sites, the SA9200 returns the address of the site that best meets the criteria for fulfilling the request.

Traditional, or Round Robin, Domain Name Service (DNS) is a rudimentary means of server load balancing. Under this method, a single hostname is mapp ed to a list of multiple server IP ad dresses. When the DNS server resolves a request for that hostname, it return s the entire list to the requestor, then sorts it (the first name drops to the end of the list). Upon recei vi ng the l ist , the cl i ent requ esto r t ypi cal ly uses the first address. The next requestor of the ho stname receives the resorted list, and again most likely u ses the current first name. The list is resorted again, so that each sequential request sees a different “first choice” than the previous one. The chief benefit of Round Robin DNS is that it allows requests to be distributed to multiple hosts and, in theory, provides a layer of redundancy. On the negative side, the DNS server has no knowledge of the status of the sites to which it sends requests. Receiving sites may be heavily loaded or dead, thus the potential is high for unacceptably slow replies error messages to clients, which is out of the site operator’s control.

C H A P T E R 2 Authoritative DNS Servers

SA9200

(Los Angeles)

(San Diego)

Authoritative DNS Servers

SA8200

Client

SA8200

(Chicago)

ns.mstd-ex.com (Chicago)

Authority for msd-ex.com

Local DNS server

(San Diego)

Multi-Site Load Balancing

The DNS maps, or “resolves” hostnames into IP addresses. It is, in effect, a distributed database operating through a distributed, hierarchical system of Domain Name Servers. Thus, if t he local DNS server cannot resolve a name, it looks “upstream” to consult a Root Domain Server for help. The Root Domain Server in turn asks the Authoritative Name Server (i .e., th e owner of t he name i t is tryi ng to resolve) to return the appropriate IP address for the requested name.

To illustrate

1. The client sends a query to its configured DNS (all clients are configured with the address of their DNS server) to resolve a particular domain name (e.g., www.mstd-ex.com).

2. The client DNS server sends a query to the Root Domain server for the .com domain (every DNS server is configured with the root server information) to resolve mstd-ex.com.

3. The Root Domain server responds with the address of the Authoritative DNS server fo r the mstd-ex.com domain.

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

4. The client DNS server sends a query to the mstd-ex.com Authoritative DNS server to resolve www.mstd-ex.com.

5. The Authoritative DNS server responds to the client DNS server with the IP address of www.mstd-ex.com.

6. The client DNS server responds to the client with the IP address of www.mstd-ex.com.

In the discussion above, the SA9200 acts as authorit ative DNS server for zone.mstd-ex.com, which is the zone in which the name www.mstd-ex.com resides.

Multi-Site Traffic Managemen t Using HP Traffic Directors

Multi-site load balanc ing solves most of the prob le ms inherent in Round Robin DNS. Under the server load balancing model, servers are aggregated in a “server farm” behind a lo ad balan cer kn own by a Virtual IP address or “service.” (The service is the IP address of which the external network is aware.) By keeping track of such metrics as number of connections, which services are running, response time and the like, the load balancer knows the status of the servers. The SA9200 retrieves metrics from the lo ad b alancer. Thus, when a client requests the service, the SA9200 routes it to the site who has a server best able to fulfill it.

If the data center has an HP Traffic Director, the SA9200 works in concert with the “agents” in the load balancers by continually communicating with each site’s agent through site verification protocol. This keeps th e SA9200 infor med of the following:

• Health of the load balancers.

• Individual service health and availability.

• CPU utilization of load balancers.

• Response time for each service.

• Number of connections to each load balancers.

Site verification protocol information is encrypted for secure communication between an HP Traffic Directors and the SA9200.

C H A P T E R 2 Multi-Site Traffic Management Without HP Traffic Directors

Multi-Site Traffic Management Without H P Traffic Directors

Typical Configuration

The SA9200 can support data centers, whether or not they have an HP Traffic Director. Without t hese HP products, the SA9200 can monitor site service availability by using an ISV met ho d:

• Ping (ICMP)

• TCP Open probe

• HTTP URL probe

The SA9200 can be used with a wid e variety of topolog ies but a basic example of a SA9200 configuration might consist of two SA9200s and four HP SA8200s (one SA9200 at each location that the site is distributed across, and two SA8200s or two SA8220s in serial failover mode for each location). For illustrative p urposes, these dev ices are configured to balance www.mstd-ex.com. Because the SA9200 does not resolve records aside from hostnames (e.g., no MX records or reverse DNS lookups), your existing DNS server should remain authoritative for the domain, mstd-ex.com. A new zone, zone.mstd- ex.com, must be created and your existing DNS server must delegate authority for this zone to all www.zone.mstd-ex.com is created for www.mstd-ex.com. This zone and alias are transparent to users connecting to your site. They still requests www.mstd-ex.com and are referred to the op timal site by the SA9200.

of the SA9200s. An alias,

Los Angeles location Chicago location

SA9200 primary

SA8200 or SA8220s

servers

Clie nt

SA9200 Overview - A Basic Configuration

Internet

SA9200 secondary

SA8200 or SA8220s

servers

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Site Balancing Methods

The SA9200 supports six si te-b alancing methods or algor i th ms. Th e operator chooses the method most appropriate to the deployment to optimize traffic volume, priority, resource ava ilability, and the overall desired outcome.

Weighted Algorithms

Metric Algorithms

• Weighted Round Robin - Two differences distinguish this

method from traditional, or Round Robin, DNS. First, the SA9200 is aware of the status of the si tes i t balances thus, unlike legacy Round Robin, it does not indiscri minately send r equests to servers that have gone down or are otherwise unable to fulfill requests. Second, Weighted Round Robin allows the operator to skew the loading among availabl e sit e servi ces on t he basi s of a n assigned “weight.” (Weight takes into account differences in capabilities of site services.) Weighting allows the operato r to adjust loading on a percentage basis. For example, Site A is assigned a weight of 1, Site B, 2, and Site C, 7. Thus, Site A receives 10% of the traffic, Site B, 20% and Site C, 70%. This method can ensure the most efficient use of those sites with greater “horsepower,” while preventing the overtaxin g of less powerful ones.

• W eighted Random - T he Weighted Random method is similar to

Weighted Round Robin with the exception that requests are not fulfilled serially. IP addresses are resolved in a random fashion. The weighting is accomplished as above. The benefit of this algorithm is that it is more effective at n ormalizing, or leveling, load.

Using DNS to balance multiple sites is more effective when the referrals are based upon knowled ge of the actual loads on the servers. In addition, balancing effect ivene ss no ti ceab ly i ncrease d whe n b ackto-back referrals to the same site were not made even if metrics indicated one site service was the best both times. T he SA9200 metric algorithms reflect both of those findings.

These balancing algori thms are not availa ble for sites that do not have HP load balancers:

• Response Time - The Response Time method directs requests to

the site that has the fastest aggregate (i.e., across all servers) response time for the requested service. Likely users of this

C H A P T E R 2 Metric Algorithms

method are enterprises that have identified the efficient fulfillment of a specific type or types of traffic as being crucial to their business goals.

• Least Connections - The Least Connections method sends

requests to the site with fewest number of connections. This method permits the most efficient management of requests that are likely to require connections of long duration, such as FTP.

• CPU Utilization of Local Load Balancer - This method directs

clients to the site whose load b a lancer has the lightest workloa d. The benefit of this method is most evident when used with sites performing processor-intensive Layer 7 load balancing.

Managing Unequal Site Servers

There is a “factor” command to determine a th re shold factor in the event of two unequal servers. (see config dns zones <zonename> hostnames <hostname> siteservices <siteservicename> factor in Chapter 6, “CLI Reference.”)

The SA9200 determines which IP address to return for a hostname, based on the performance of the IP address and port at a site. The three-step process is:

1. Determine the metric(s) with the smallest value.

2. Determine whether any remaining service(s) are close enough to this best value to also be co nsidered. The quantifi cation of “close enough” is the factor. A factor o f 0 means con sider only services with the best value.

3. Randomly choose from all the services identified in the first two steps.

A good example of the usefulness of this “close enough” threshold factor is when two unequal servers are deployed behind di fferent load balancers. Server A may be capable of handling 3000 connections per second. Server B may also be capable of handling that many connections per second, but is also servi ng more sites than Server A. The realistic connection limit of Server B may therefore only be about 500 connections per second. If Server A has 900 connections and Server B has 400 connections, then Server B is the site with the least number of connections, alth ough it is already 80% load ed while Server A is only 30% l oad ed. The better choic e woul d be to give the traffic to server A. However, the SA9200 has no knowledge of the actual load potential of the servers underneath the load balancers it monitors. Therefore it allows the next best thing. For example, it

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

allows the user to declare that if Server A is within 24 00 connections (80% of maximum) of Server B, consider referrals to Server A even if Server B is the lowest. The factor setting would be 2400 for the service associated with Server A and 0 for the service associated with Server B.

Flash DNS

Partial Failures

Network topology can greatly affect the overall transfer rate between a site and a client. A solution is to replicate sites on multiple networks (which are sometimes also distributed geographically). Without a SA9200, it can be cumbersome to provide users with a list of mirror sites and then let them choose which one appears to be best for them.

Flash DNS addresses this problem by letting a SA9200 at each network site send out responses to a DNS query for the site host name. If all responses are sent at the same time then the site that has the least network latency connecting to the user should get its response to the user first. The user ignores all the other responses.

Since many enterprise clients are behind firewalls that perform Network Address Translation (NAT), by default, the SA9200 performs source IP using the IP ad dress of the SA9200 that o riginally received the DNS request. This feature can be disabled.

The SA9200 maintains the current metric state of each service on a per host basis. A “service” is an IP address and port at a site. The maintained state has four levels relating to the amount of information that the SA9200 has about each service.

Each load balancin g method handles parti al failures in t he same basic way. Each balancing method always tries t o f ind at l east one servi ce with a metric status of “OK” with which to balance. If no services are available at this highest metric state, and it is not using a metric balancing method, then it looks for at least one service with a metric state of “No Services”. If none are found t hen it look s for at lea st one service with a metric state of “No Metrics”. Finally, if no services have been found at a high enough metric state level to balance normally, it perfo rms a Round Robin selection among al l the enabl ed services.

C H A P T E R 2 Partial Failures

Status: OK

This state indicates that the required services behind this service are available on the associated load balancer. The metrics information for this service are current and can be used for metric load balancing.

Status: No Services

This state indicates that services other than the one(s) configured as required for the associated host are not available on the load balancer. Other services with this same service are available. Metric load balancing is not available for this service.

Status: No Metrics

This state indicates that the HP Traffic Director is not advertising any services that use this service. Metric load balancing is not available for this service.

Status: No Connection

The SA9200 has lost or been unable to establish a connection to the fulfillment agent on the load balancer. No metrics information on any services from this load balancer is available. No load balancing methods are available for this service. It may only participa te in NonWeighted Round Robin load balancing.

Service Standby

To achieve site service redundancy, customers often want to have backup services that are completely dark to normal traffic, but are instantly available to take over for a failed site service. The transition of traffic from the failed site service to the standby site service occurs without the need of operator intervention.

The Service Standby feature allows the designation of a site’s services for standby. If there is a SA9200 located at the site, its operation is unaffected and continues in resolving queries and referring to active services. When the SA9200 has detected a failed service, the failed service is not used in referrals. Once a failed service has been deemed active again, no further referrals are made to the standby service.

The determination to use or not use a standby site service is only made upon receipt of a query that involves the service. Therefore, a standby service is not activated to replace a failed service until a query is received, and a failed service is not shown as active until after a query is received.

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Multiple VI P Response

The DNS response from a SA9200 may contain multiple answers. The number of answers and whether to include stand-by VIPs can be configured.

Active VIPs are included first in the response. A stand-by VIP is treated as an active VIP, if it is marked as “IN USE” due to a failed VIP. Stand-by VIPs are included after the active VIPs: (a) if the configuration is se t to incl ude th em and, (b ) the number of req uested additional VIPs in the response has not been met.

When using multi-VIP r esponse with Flash load balancing, the Flash response attemp ts to use VIPs wi thin the same pee r group first bef ore including VIPs from the other peer groups.

Definitions

Understanding of the SA9200 requires some specialized terms. The definitions provided here are specific to the context of multi-site load balancing and the operation of the SA9200, thus there may be su btle differences between these and those offered in other sources.

Agent is a component of an HP Traffic Director that gathers metric data and transmits it to the SA9200. For the purposes of the discussions in this user guide, “agent” is synonymous with “Traffic Director” or “e-Commerce Director.”

Agent IP refers to the real IP ad dress of an HP Traffic Director in i ts role as an agent to a SA9200.

Intelligent Site Verification (ISV) is used to directly determine the availability of (1) a service or, (2) a service that is balanced using a third-party load balancer. Methods of verification include a site ping, TCP connect, and HTTP probe.

ISV Group refers to a collection of services available at a physical site. All services in a group share th e same ISV polling parameters.

If multi-VIP standby is enabled when using the Flash load balancing method, standby VIPs from a site are not included if all of the VIPS are (1) standby and, (2) not marked “IN USE” due to a failed VIP at another site.

C H A P T E R 2 Definitions

Primary SA9200 is a SA9200 that automatically transfers (copies) configuration inf ormation to secondar y SA9200s (through the Glo bal Sync process). Configuration may only be changed on a Primary SA9200.

Service is the Virtual IP (VIP) and port number of an application service available at a site.

Authoritative Server is a DNS name server that has co mplete name space information regarding the hosts within a given zone (see below).

Authority is an attribute of a DNS name server with respect to a specific part of the DNS name space, or zone (see below). A name server is said to have authority over a zon e, by whi ch that se rver has complete name space information for that zone.

Zone is a portion of a DNS name space for which a given name server has complete name space information. When a name server receives a request for a host outside of its zone, it replies with the name of the name server that is authoritative for a different zone and is likely to have the specific inform a tion required to satisfy the re quest.

C H A P T E R 2 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Notes

CLI Configuration

Custom/Manual Configuratio n

You can manually change any specific configuration parameters if any of the Quick Start Wizard default settings are not sufficient for your site.

It is recommended that you use the custom configuration method only after you have comp leted the initial config uration with the Quick Start Wizard. See the HP Multi-Site Traffic Director Server Appliance SA9200 Getting S tarted Guide for instructions on using the Quick Start Wizard.

Command Line Syntax

This User Guide uses the following syntax when referring to CLI commands.

Angled brackets (<>)

Straight brackets ([ ])

Angled brackets designate where you enter variable parameters.

Choices of parameters appear between straight brackets, separated by vertical bars.

Command Line Syntax

C H A P T E R 3 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

SA9200 (Primary)

host name: ns1.xyz-ex.com IP ad dress : 10.54 .67.2

HP Traffic Director

IP address 10.54.67.4

service VIP 10.54.67.5 port 80 service VIP 10.54.67.6 port 80

service VIP 10.54.67.7 port 255

service VIP 10.54.67.8 port 255

generic load balancer

IP address 10.54.67.3

Braces ({})

Optional commands or parameters appear between braces.

Commands shown as they are entered after the

Bold

CLI prompt appear in bold type. (The prompt appears in normal typeface to distinguish it from the command text.)

Separates choices of input parameters within

Vertical bar

(|)

straight brackets. You may choose only one of a set of choices separated by the vertical bar. (Do not include the vertical bar in the command.)

Data Center 1

Network Topology

M ap o f

www.xyz-ex.com

Data Center 2

Command Line Syntax

generic load balancer

IP a d d ress 1 0.10 0.68 .3

service VIP 10.54.68.7 port 255

service VIP 10.54.68.8 port 255

HP Traffic Director

IP address 10.100.68.4

service VIP 10.100.68.5 port 80

service VIP 10.100.68.6 port 80

SA9200 (Secondary & Peer)

host name: ns2.xyz-ex.com IP address: 10.100.68.2

Adding a Secondary SA9200

Sample Network Topology

Now that the primary SA9200 is up and running, the additional SA9200s can be easily added by configuring them as secondary SA9200s. They receive all their configuration information from the designated primary SA9200 t hrough the Glob al Sync process, whi ch automatically transfers the primary SA9200 configuration to any secondary SA9200s.

Similar to a typical DNS server, all SA9200s are treated as equals by other DNS servers. The terms of primary and secondary only refers to where a SA9200 gets its new configuration information. The SA9200 only allows the configuration to be changed on a primary

C H A P T E R 3 Custom/Manual Configuration

SA9200. Secondaries get their configuration from their designated primary SA9200 and store a copy of the received configuration locally. Should a secondary be unable to contact a primary it functions normally us ing its sto red confi gura tion. All SA9200s have the same picture of the current Agent metrics and are equally cap able of responding. Should one fail the existing DNS protocol automatically routes requests to the non-failed SA9200s.

The theoretical secondary ns2.xyz-ex.com (IP 10.100.68.2) can resolve requests for www.somedomain.xyz-ex.com by becoming a secondary of the SA9200 at 10.54.67.2. From the CLI on the proposed second SA9200, execute the command:

NOTE: User-entered names and IP addresses in the example are for illustrative purpo ses only. The appropriate values for your installation may vary.

Creating Agents

NOTE: An HP Traffic Director refers to an HP Traffic Director Server Appliance, Models SA7200 and SA7220; or HP e-Commerce Traffic Director Server Appliance, Models SA8200 and SA8220.

#config dns secondary 10.54.67.2 Warning: Your current dns configurations will

be lost. Are you sure you want to become a Secondary

(Yes/No):yes Now running as a Secon dary.

If the DNS configuration of 10.54.67.2 is changed, the new configuration can be prop agated to 10.100.68.2 by the commit all command.

An agent refers to the HP Traffic Director at each site. They are used to keep the SA9200 informed of site status, response time, and number of current connections of the server farm they are balancing.

To add an agent, type the following:

HP SA9200# config dns agents create lb1 ip

10.54.67.4 HP SA9200# config dns agents create lb2 ip

10.100.68.4

C H A P T E R 3 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Associating Services with Agents

Creating Zones

Creating Authority Records

NOTE: The SA9200 must be authoritative for this zone—the existing DNS server should delegate the domain to the SA9200.

Next, services must be associated with agent(s):

HP SA9200# config dns agents lb1 services create 10.54.67.5:80

HP SA9200# config dns agents lbl services create 10.54.67.6:80

HP SA9200# config dns agents lb2 services create 10.100.68.5:80

HP SA9200# config dns agents lb2 services create 10.100.68.6:80

The next step is to create a zone (e.g., somedomain.xyz-ex.com) on the SA9200. The command to do this is:

HP SA9200# co nfig dns zones create somedomain.xyz-ex.com

Next, authority records for y our two SA9200s are created. These sites are used to tell DNS servers who they can query directly for other hosts in the current zone. In order for the SA9200 to perform effectively, only SA9200s should be authoritative for the zone.

For example, hostname ns1.xyz-ex.com at IP address 10.54. 67.2 and hostname ns2.xyz-ex.com at 10.100.68.2. The authoritative DNS servers for xyz-ex.com should contain records for these hostnames, as well as the corresponding NS records for somedomain.xyz-ex.com. (See the section, Existing DNS Servers.)

HP SA9200# co nfig dns zones somedomain.xyzex.com

HP SA9200/config/dns/zones/somedomain.xyzex.com# create-authority ns1.xyz-ex.com ip

10.54.67.2

Create Authority Successful HP SA9200/config/dns/zones/somedomain.xyz-

ex.com# create-authority ns2.xyz-ex.com ip

10.100.68.2

Create Authority Successful

C H A P T E R 3 Custom/Manual Configuration

HP SA9200/config/dns/zones/somedomain.xyzex.com# info

Zone: somedomai n.xyz-ex.com Authority Records TTL: 7200 Authority Name: ns1.xyz-ex.com

Authority IP: 10.54.67.2 Authority Name: ns2.xyz-ex.com

Authority IP: 10.100.68.2

Creating Hosts

Next, the hostname www.somedomain.xyz-ex.com is created:

HP SA9200/config/dns/zones/somedomain.xyzex.com# hostnames create www

Create Hostname Successful

The next step is to map the services www.somedomain.xyz-ex.com to the load balancer. The following assumes the IP addresses of the load balancer to be 10.54.67.4 (service 10.54.67.5:80) and 10.100.68.4 (service 10.100.68.5:80), and that th e agents are enabled and run ning on the default port 1999. (Agents are enabled or disabled using the CLI of an HP Traffic Director, with the command, config sys multisite <e nabl e|di sable> .) It is assumed t hat t he a gent names are the same as their IP addresses.

HP SA9200/config/dns/zones/somedomain.xyzex.com# hostnames www siteservices

HP SA9200/config/dns/zones/somedomain.xyzex.com/hostnames/www/siteservices# map

lb1:10.54.67.5:80

Site Service Mapped HP SA9200/config/dns/zones/somedomain.xyz-

ex.com/hostnames/www/vips# map

lb2:10.100.68.5:80

Site Service Mapped

C H A P T E R 3 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Committing the Configuration

NOTE: If the SA9200 was not configured with a primary name server during setup from the Boot Monitor, the nslookup command fails.

The commit command is used to put the configuration into effect.

HP SA9200/config/dns/zones/somedomain.xyzex.com/hostnames/www/vips# commit all

Warning: Your active configuration will be overwritten.

Are you sure you want to commit the configuration (yes|no)? yes

Configuration has been committed

NSLookup

The nslookup utili ty can verify that the SA9200 is correc tly resolvin g www.somedomain.xyz-ex.com:

HP SA9200# nslookup www.somedomain.xyz-ex.com

Server: server1.xyz-ex.com Address: 10.168.16.4

Name: www.somedomain.xyz-ex.com Address: 10.168 .16.23

Configure DNS Servers

The existing DNS server or servers must be correctly configured to work with the SA9200s. Entries need to be made that delegate the responsibility of resolving DNS quer ies fo r www.xyz-ex.com to the SA9200s. This can be done in one of two ways. The first way is to delegate the entire zone to the SA9200. This works fine as long as only type A records need to be returned for this zone. The SA9200 is a high performance specialized DNS server and supports only the more common type A records.

The recommended way of configuring your existing DNS server is delegate partial authority by aliasing. All of the SA9200s (both primary and all secondaries) must b e included in the authority record (NS) portion of the delegation.

C H A P T E R 3 Configure DNS Servers

Multiple-VIP Response

A DNS response may contain multiple answers. A standby VIP is automatically considered as a resp onse if it is marked “IN USE” due to a failed VIP. When multi-VIP standb y is enabled, standby VIPs are included in a response if the number of additional VIPs in the response has not been met

dns zones <zonename> hostnames <hostname> multi-vipstandby enable.

HP SA9200#config dns zones somedomain.xyz- ex.com hostnames www multi-vip-standby enable

. To include standby VIPs, type config

The number of additional answers in a response can be configured. The range is from 0 to 15.

HP SA9200#config dns zones somedomain.xyzex.com hostnames www add -r ec-responses 4

To verify whether multi-VIP standby is enabled or check the numb er of additional responses, type config dns zones

<zonename> hostnames <hostname> info.

HP SA9200#config dns zones somedomain.xyz- ex.com hostnames www info

C H A P T E R 3 HP Multi-Site Traffic Director Server Appliance SA9200 User Guide

Notes

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