3.4.2 Load Balancing - D-Link DSR-150 User Manual

Unified Services Router

Secondary WAN: Selected WAN is the secondary link.
Failover Detection Settings: To check connectivity of the primary internet link, one of the following
failure detection methods can be selected:

DNS lookup using WAN DNS Servers: DNS Lookup of the DNS Servers of the primary link
is used to detect primary WAN connectivity.

DNS lookup using DNS Servers: DNS Lookup of the custom DNS Servers can be specified
to check the connectivity of the primary link.

Ping these IP addresses: These IP's will be pinged at regular intervals to check the
connectivity of the primary link.

Retry Interval is: The number tells the router how often it should run the above configured
failure detection method.

Failover after: This sets the number of retries after which failover is initiated.

DSR-1000, DSR-1000N, DSR-500, DSR-500N, DSR-250, DSR-250N, DSR-150, and DSR-150N
support 3G USB Modem as a failover link when the internet access is lost.

3.4.2 Load Balancing

This feature allows you to use multiple WAN links (and presumably multiple ISP's) simultaneously.
After configuring more than one WAN port, the load balancing option is available to carry traffic
over more than one link. Protocol bindings are used to segregate and assign services over one WAN
port in order to manage internet flow. The configured failure detection method is used at regular
intervals on all configured WAN ports when in Load Balancing mode.
DSR currently support three algorithms for Load Balancing:
Round Robin: This algorithm is particularly useful when the connection speed of one WAN port
greatly differs from another. In this case you can define protocol bindings to route low-latency
services (such as VOIP) over the higher-speed link and let low-volume background traffic (such as
SMTP) go over the lower speed link. Protocol binding is explained in next section.
Spill Over: If Spill Over method is selected, WAN1 acts as a dedicated link till a threshold is
reached. After this, WAN2 will be used for new connections. You can configure spill-over mode by
using following options:

Load Tolerance: It is the percentage of bandwidth after which the router switches to secondary
WAN.

Max Bandwidth: This sets the maximum bandwidth tolerable by the primary WAN.
If the link bandwidth goes above the load tolerance value of max bandwidth, the router will spill-
over the next connections to secondary WAN.
For example, if the maximum bandwidth of primary WAN is 1 Kbps and the load tolerance is set to
70. Now every time a new connection is established the bandwidth increases. After a certain number
of connections say bandwidth reached 70% of 1Kbps, the new connections will be spilled-over to
secondary WAN. The maximum value of load tolerance is 80 and the least is 20.

DSR-1000, DSR-1000N, DSR-500 and DSR-500N support the traffic load balancing between physical
WAN port and the 3G USB Modem.
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User Manual