Overview of Geographic Load Balancing with Envoy
Equalizer Installation and Administration Guide
239
1. Figure 51 is an illustration of a client in California whose local DNS server has contacted Envoy Site A to
resolve the destination domain name for the client request -- in this example,
www.coyotepoint.com
.
Figure 51 Sending name resolution requests to an Equalizer in a GeoCluster
2. Site A sends a
geographic query protocol probe (GQP)
to all the other Envoy sites in the GeoCluster for the
requested domain (this GeoCluster has the same name --
www.coyotepoint.com
). The probe is received by a
special Envoy
agent
running at each site in the cluster (the agent for a site starts when you configure Envoy for
the site). Site A also queries its local Envoy agent (see Figure 52).
Figure 52 The selected Equalizer queries other Equalizers and its own servers in the GeoCluster
The GQP probes contain information about the requesting client and the local resource (i.e., local cluster) that is
being requested by the client.
If
ICMP triangulation
is enabled, the GQP probes also tell the sites to send an ICMP echo request (‘
ping
’) to
the client’s local DNS server, and to return the DNS server’s response time in their GQP response to Site A.
This provides more accurate client location information to Envoy in the case where a resource is available at
more than one site.
Envoy Site B
(West Coast USA)
Envoy Site A
(East Coast USA)
Internet
Envoy Site C
(Europe)
Client
(California, USA)
Client’s
Local DNS
DNS
Authoritative
DNS
for
coyotepoint.com
DNS
Envoy Site B
(West Coast USA)
Envoy Site A
(East Coast USA)
Internet
Envoy Site C
(Europe)
Client
(California, USA)
GQP
GQP
G
Q
P
Содержание E350GX
Страница 18: ...Chapter Preface 18 Equalizer Installation and Administration Guide ...
Страница 38: ...Chapter 1 Equalizer Overview 38 Equalizer Installation and Administration Guide ...
Страница 50: ...Chapter 2 Installing and Configuring Equalizer Hardware 50 Equalizer Installation and Administration Guide ...
Страница 62: ...Chapter 3 Using the Administration Interface 62 Equalizer Installation and Administration Guide ...
Страница 80: ...Chapter 4 Equalizer Network Configuration 80 Equalizer Installation and Administration Guide ...
Страница 110: ...Chapter 5 Configuring Equalizer Operation 110 Equalizer Installation and Administration Guide ...
Страница 208: ...Chapter 7 Monitoring Equalizer Operation 208 Equalizer Installation and Administration Guide ...
Страница 240: ...Chapter 8 Using Match Rules 238 Equalizer Installation and Administration Guide ...
Страница 258: ...Chapter 9 Administering GeoClusters 254 Equalizer Installation and Administration Guide Envoy Configuration Worksheet ...
Страница 262: ...Appendix A Server Agent Probes 258 Equalizer Installation and Administration Guide ...
Страница 274: ...Appendix B Timeout Configuration 270 Equalizer Installation and Administration Guide ...
Страница 280: ...Appendix D Regular Expression Format 276 Equalizer Installation and Administration Guide ...
Страница 296: ...Appendix E Using Certificates in HTTPS Clusters 292 Equalizer Installation and Administration Guide ...
Страница 310: ...Appendix F Equalizer VLB 306 Equalizer Installation and Administration Guide ...
Страница 318: ...Appendix G Troubleshooting 314 Equalizer Installation and Administration Guide ...