Brocade Communications Systems 12.4.00 Syntax no round-robin Enabling the Round-Trip-Time metric

1 Host-level policies for site selection

Syntax: [no] round-robin

Enabling the Round-Trip-Time metric

You can enable the GSLB metric for the round-trip time between the remote ServerIron ADX and the DNS client.

The Round-trip time (RTT) is the amount of time that passes between when the remote site initiates a TCP connection (sends a TCP SYN) to the client and when the remote site receives the client’s acknowledgment of the connection request (sends a TCP ACK). The GSLB ServerIron ADX learns the RTT information from the site ServerIron ADXs through the GSLB protocol and uses the information as a metric when comparing site IP addresses. The GSLB ServerIron ADX uses this metric when evaluating the sites in a DNS reply to choose the best site.

You can enable or disable the Round Trip Time (RTT) metric and configure RTT tolerance for the host-level policy. You can configure other parameters for the global GSLB policy, but not for the host-level policy. If a host-level policy is applied to a host/zone, then the GSLB ServerIron ADX will use the values defined in the global GSLB policy for RTT parameters that cannot be configured under the host-level policy. These parameters are:

•RTT cache interval

•RTT cache prefix length

•RTT explore percentage

To enable the Round Trip Time metric for the host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# round-trip-time

Syntax: [no] round-trip-time

Changing the RTT tolerance

To change the RTT tolerance for the host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc GSLB-ServerIronADX(config-gslb-host-policy-abc)# round-trip-time tolerance 20

Syntax: [no] round-trip-time tolerance <num>

Enabling the weighted IP metric

The weighted IP metric provides a way for the ServerIron ADX to distribute GSLB traffic among IP addresses in a DNS reply, based on weights assigned to the IP addresses.

To enable weighted IP for the host-level policy, enter commands such as the following:

GSLB-ServerIronADX(config)# gslb-host-policy abc

GSLB-ServerIronADX(config-gslb-host-policy-abc)# weighted-ip

Syntax: [no] weighted-ip

Use the no form of the command to disable the weighted IP metric for the host-level policy.

Enabling the weighted site metric

The weighted site metric provides a way for the ServerIron ADX to distribute SLB traffic among GSLB sites based on weights configured for the sites.

To enable the weighted site metric for a host-level policy, enter commands such as the following:

124	ServerIron ADX Global Server Load Balancing Guide
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