What You Need To Know - ZyXEL Communications USG FLEX H Series User Manual

• Use the Add System Default screen
algorithm for the system default trunk.

7.6.1 What You Need to Know

• Add WAN interfaces to trunks to have multiple connections share the traffic load.
• If one WAN interface's connection goes down, the Zyxel Device sends traffic through another
member of the trunk.
• For example, you connect one WAN interface to one ISP and connect a second WAN interface to a
second ISP. The Zyxel Device balances the WAN traffic load between the connections. If one
interface's connection goes down, the Zyxel Device can automatically send its traffic through
another interface.
You can also use trunks with policy routing to send specific traffic types through the best WAN interface
for that type of traffic.
• If that interface's connection goes down, the Zyxel Device can still send its traffic through another
interface.
• You can define multiple trunks for the same physical interfaces.
LAN user A logs into server B on the Internet. The Zyxel Device uses wan1 to send the request to server B.
1
The Zyxel Device is using active/active load balancing. So when LAN user A tries to access something on
2
the server, the request goes out through wan2.
The server finds that the request comes from wan2's IP address instead of wan1's IP address and rejects
3
the request.
If link sticking had been configured, the Zyxel Device would have still used wan1 to send LAN user A's
request to the server and server would have given the user A access.
Load Balancing Algorithms
The following sections describe the load balancing algorithms the Zyxel Device can use to decide which
interface the traffic (from the LAN) should use for a session. In the load balancing section, a session may
refer to normal connection-oriented, UDP or SNMP2 traffic
the Zyxel Device refers to the actual bandwidth provided by the ISP and the measured bandwidth refers
to the bandwidth an interface is currently using.
Weighted Round Robin
Round Robin scheduling services queues on a rotating basis and is activated only when an interface has
more traffic than it can handle. A queue is given an amount of bandwidth irrespective of the incoming
traffic on that interface. This queue then moves to the back of the list. The next queue is given an equal
amount of bandwidth, and then moves to the end of the list; and so on, depending on the number of
queues being used. This works in a looping fashion until a queue is empty.
The Weighted Round Robin (WRR) algorithm is best suited for situations when the bandwidths set for the
two WAN interfaces are different. Similar to the Round Robin (RR) algorithm, the Weighted Round Robin
(WRR) algorithm sets the Zyxel Device to send traffic through each WAN interface in turn. In addition, the
WAN interfaces are assigned weights. An interface with a larger weight gets more chances to transmit
traffic than an interface with a smaller weight.
Chapter 7 Interfaces
(Section 7.7.2 on page
USG FLEX H Series User's Guide
130
134) to configure the load balancing
The available bandwidth you configure on
.