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Chapter 8 Trunk
ZyWALL 110/310/1100 Series User’s Guide
178
• If that interface’s connection goes down, the ZyWALL can still send its traffic through another
interface.
• You can define multiple trunks for the same physical interfaces.
Link Sticking
You can have the ZyWALL send each local computer’s traffic that is going to the same destination
through a single WAN interface for a specified period of time. This is useful when a server requires
authentication. For example, the ZyWALL sends a user’s traffic through one WAN IP address when
he logs into a server B. If the user’s subsequent sessions came from a different WAN IP address,
the server would deny them. Here is an example.
Figure 100 Link Sticking
Load Balancing Algorithms
The following sections describe the load balancing algorithms the ZyWALL can use to decide which
interface the traffic (from the LAN) should use for a session
3
. The available bandwidth you
configure on the ZyWALL refers to the actual bandwidth provided by the ISP and the measured
bandwidth refers to the bandwidth an interface is currently using.
Least Load First
The least load first algorithm uses the current (or recent) outbound bandwidth utilization of each
trunk member interface as the load balancing index(es) when making decisions about to which
interface a new session is to be distributed. The outbound bandwidth utilization is defined as the
measured outbound throughput over the available outbound bandwidth.
Here the ZyWALL has two WAN interfaces connected to the Internet. The configured available
outbound bandwidths for WAN 1 and WAN 2 are 512K and 256K respectively.
3. In the load balancing section, a session may refer to normal connection-oriented, UDP or SNMP2 traffic.
LAN
wan2
A
B
1
2
3
wan1