Specifications

Chapter 3: Configuring Equalizer Hardware
30 Equalizer Installation and Administration Guide
Envoy across firewalled networks, you also need to configure the firewalls to allow traffic between
Envoy sites and between the Equalizer and clients.
Configuring the Authoritative Name Server to Query Envoy
To delegate authority to the Envoy sites, you must configure the authoritative name server(s) for the
domains that are to be geographically load-balanced. You also must delegate each of the fully-
qualified subdomains to be balanced.
For example, assume that you want to balance
www.coyotepoint.com across a geographical
cluster with two Envoy sites,
east.coyotepoint.com and west.coyotepoint.com. In this
case, you configure the name servers that handle the
coyotepoint.com domain to delegate
authority for
www.coyotepoint.com to both east.coyotepoint.com and
west.coyotepoint.com. When a client asks to resolve www.coyotepoint.com, the name
servers should return name server (NS) and alias (A) records for both sites.
Using Geographic Load Balancing with Firewalled Networks
Equalizer sites communicate with each other using Coyote Point’s UDP-based Geographic Query
Protocol. Similarly, Equalizer sites communicate with clients using the DNS protocol. If a network
firewall protects one or more of your sites, you must configure the firewall to permit Equalizer
packets to pass through.
To use geographic load balancing with firewalled networks, you need to configure the firewalls so
that the following occurs:
• Equalizer sites communicate with each other on UDP ports 5300 and 5301. The firewall must
allow traffic on these ports to pass between Envoy sites.
• Equalizer sites and clients can exchange packets on UDP port 53. The firewall must allow
traffic on this port to flow freely between an Equalizer server and any Internet clients so that
clients trying to resolve hostnames via the Equalizer DNS server can exchange packets with
Equalizer sites.
Equalizer sites can send ICMP echo request packets (i.e., a ‘ping’) through the firewall and receive
ICMP echo response packets from clients outside the firewall. (When a client attempts a DNS
resolution, Equalizer sites send an ICMP echo request packet to the client; the client might respond
with an ICMP echo response packet.)
Testing Your Basic Configuration
Once you have installed and configured Equalizer and your servers, perform tests to verify that
Equalizer is working properly.
To perform these tests, you need the following:
• A test machine on the internal network (the same physical network as the servers; one of the
server machines can be used for this purpose).
• If you have a two-network configuration, a test machine on the external network.
• A client machine somewhere on the Internet, to simulate a “real-world” client. This machine
should be set up so that the only way it can communicate with your servers or Equalizer is
through your Internet router.