Brocade Communications Systems ServerIron ADX 12.4.00 - Manual (Page 160)

148 ServerIron ADX Global Server Load Balancing Guide
53-1002437-01
Round-trip times
1
In the example above, assume that the GSLB ServerIron ADX is configured as Mode 2. Also assume
that this GSLB ServerIron ADX is providing GSLB for www.foo.com where the IP addresses for this
domain are IP-1, IP-2, and IP-3. IP-1 is a VIP on ServerIron ADX-1. IP-2 is a VIP on ServerIron ADX-2.
IP-3 is a VIP on ServerIron ADX-3.
If a DNS resolution request comes from LDNS 201.53.10.1, then GSLB ServerIron ADX uses only
the RTT information for IP-1 which is configured on ServerIron ADX 1.1.1.102 (rtt = 7ms, source =
active). Since the GSLB ServerIron ADX in configured as Mode 2, only actively reported RTT values
are used during the selection. The RTTs for IP-2 and IP-3 are not used since the source of these
RTTs is passive.
The RTT algorithm mode can be configured globally in a global GSLB policy or locally in a host-level
GSLB policy. Placing the modes in different policies allows you to use different RTT algorithm
modes for different hosts. The default RTT algorithm mode for a global or host level GSLB policy is
Mode 1.
Using only passive RTT
To configure a global GSLB policy to use only passive RTT values for RTT algorithm (Mode 1), enter
commands such as the following:
GSLB-ServerIronADX# configure terminal

GSLB_ServerIronADX(config)# gslb policy

GSLB-ServerIronADX(config-gslb-policy)# round-trip-time active-rtt
use-passive-rtts-only
To configure a host-level GSLB policy to use only passive RTT values for RTT algorithm (Mode 1),
enter commands such as the following:
GSLB-ServerIronADX# configure terminal

GSLB-ServerIronADX(config)# gslb-host-policy test

GSLB-ServerIronADX(config-gslb-host-policy-test)# round-trip-time active-rtt
use-passive-rtts-only
Syntax: round-trip-time active-rtt use-passive-rtts-only
Using only active RTT
To configure a global GSLB policy to use only active RTT values for RTT algorithm (Mode 2), enter
commands such as the following:
GSLB-ServerIronADX# configure terminal

GSLB_ServerIronADX(config)# gslb policy

GSLB-ServerIronADX(config-gslb-policy)# round-trip-time active-rtt
use-active-rtts-only
To configure a host-level GSLB policy to use only active RTT values for RTT algorithm (Mode 2),
enter commands such as the following:
GSLB-ServerIronADX# configure terminal

GSLB-ServerIronADX(config)# gslb-host-policy test

GSLB-ServerIronADX(config-gslb-host-policy-test)# round-trip-time active-rtt
use-active-rtts-only
Syntax: round-trip-time active-rtt use-active-rtts-only
Using both active and passive RTT
To configure a global GSLB policy to use both passive and active RTT values for RTT algorithm
(Mode 3), enter commands such as the following: