Link Aggregation (LACP)

Link Aggregation:

Link Aggregation provides the ability to group multiple Ethernet interfaces to form a trunk which looks and acts like a single physical interface. This feature is useful for high end deployments requiring improve throughput for traffic flowing between two interfaces.

Link Aggregation is used to increase the available bandwidth between the firewall and a switch by aggregating up to four interfaces into a single aggregate link, referred to as a Link Aggregation Group (LAG). All ports in an aggregate link must be connected to the same switch. The firewall uses a round-robin algorithm for load balancing traffic across the interfaces in a Link Aggregation Group. Link Aggregation also provides a measure of redundancy, in that if one interface in the LAG goes down, the other interfaces remain connected.

Link Aggregation is referred to using different terminology by different vendors, including Port Channel, Ether Channel, Trunk, and Port Grouping.

A link aggregation group (LAG) combines multiple network connections into a single connection.

LAG is also known as trunking, NIC teaming, NIC bonding, and EtherChannel. Link aggregation control protocol (LACP) is a part of the IEEE specification; it groups two or more physical links into a single logical link. You must turn on LACP at both ends of the link for it to function. LAG combines multiple physical links into a single logical link so that bandwidth can be increased and automatic failover is available

Link aggregation handles LAN traffic in the following ways:

• Scales bandwidth usage according to the number of links used in the group.
• Provides link redundancy with failover and failback for a continuous session.
• Facilitates load sharing across links, according to the algorithm applied in the xmit-hash-policy.
• Requires no changes to the existing network deployment or any additional hardware.

Most of Firewall supports the following LAG modes:

• Active-Backup: Provides automatic link failover or fault tolerance. In this mode, a single secondary member of the LAG remains active. If the active secondary member fails, then another member of the LAG becomes active.
• LACP (802.3ad): Provides load balancing and automatic failover. In this mode, all the links are used for forwarding traffic.