Link Policy is necessary for bandwidth channels to be effective. Different link policies can be matched based on different protocols, LAN and WAN ranges, and outbound interfaces.

Go to Policies > Bandwidth Management > Link Settings > Link Policy, and click Add. Then, the Add Link Policy dialog box appears, as shown in the following figure.

Services: Specify the protocol for packets. The protocol types include TCP, UDP, and ICMP. If there are other types, select others, and enter the protocol number range in the Protocol Number field.

LAN Settings: Set the rules for the source IP address. The IP address includes IPv4 and IPv6. Enter the specific IP address or IP range.

WAN Settings: Set the rules for the destination IP address. The IP address includes IPv4 and IPv6. Enter the specific IP address or IP range.

Link: Set the virtual line to which the packets matching this virtual line rule will match, i.e., the interface from which the packets will be forwarded.

The bandwidth channel for a virtual line will be valid only when the virtual line becomes the destination line of a virtual line rule.