SonicOS 7.1 System

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Technical Documentation > SonicOS 7.1 System > Interfaces > Interface Settings IPv4 > Configuring Link Aggregation and Port Redundancy > Link Aggregation

Link Aggregation

Link Aggregation is based on interface link speed, for example: a 10 Gbps port cannot be link aggregated with another interface that does not support 10 Gbps. Any ports that are link aggregated together should support the same link speeds.

Link Aggregation allows you to interconnect devices with two or more links between them in such a way that the multiple links are combined into one larger virtual pipe that can carry a higher combined bandwidth. Because multiple links are present between the two devices, when one link fails, the traffic is transferred through the other links without disruption. With multiple links being present, traffic can also be load balanced in such a way to achieve even distribution.

Link Aggregation is also 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 appliance 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.

There are two types of LAG: Static and Dynamic. With Static Link Aggregation all configuration settings are set up on both participating LAG components. Static LAG is already supported on NSA and SuperMassive platforms in SonicOS 6.2.7 and previous firmware releases.

Dynamic Link Aggregation is supported using LACP defined by the IEEE 802.3ad standard. LACP allows the exchange of information related to link aggregation between the members of the link aggregation group in protocol packets called Link Aggregation Control Protocol Data Units. With LACP, errors in configuration, wiring, and link failures can be detected quickly.

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

The two major benefits of LAG are increased throughput and link redundancy that can be achieved efficiently using LACP. LACP is the signaling protocol used between members in a LAG. It ensures links are only aggregated into a bundle when they are correctly configured and cabled. LACP can be configured in one of two modes:

  • Active mode ‐ the device immediately sends LACP PDUs when the port comes up.

  • Passive mode ‐ the port is placed in a passive negotiating state, in which the port only responds to LACP PDUs it receives but does not initiate LACP negotiation.

If both sides are configured as Active, LAG can be formed assuming successful negotiation of the other parameters. If one side is configured as Active and the other one as Passive, LAG can be formed as the Passive port responds to the LACP PDUs received from the Active side. If both sides are Passive, LACP fails to negotiate the bundle. Passive mode is rarely used in deployments.

During the configuration, all member ports of the same LAG must be set up on the same VLAN as the Aggregator port. Data packets received on the LAG members are associated with the parent Aggregator port using the VLAN. After the state of the Aggregator/member ports of a LAG reaches a stable Collection/Distribution state, the ports are ready to transmit and receive data traffic.

All information related to LAG such as the Aggregator ports configured, member ports that are part of the LAG, status of each of the ports that form the LAG, and the Partner MAC address received by way of LACP are displayed on the NETWORK | Switching > Link Aggregation page.

There, you will see six load balancing options are available for configuration. The load balancing option needs to be chosen during creation of a LAG when the Aggregator port is chosen. You cannot modify the load balancing option after the LAG is created.

  • SRC_MAC, ETH_TYPE, VLAN, INTF

  • DST_MAC, ETH_TYPE, VLAN, INTF

  • SRC_MAC, DST_MAC, ETH_TYPE,VLAN, INTF

  • SRC_IP, SRC_PORT

  • DST_IP, DST_PORT

  • SRC_IP, SRC_PORT, DST_IP, DST_PORT

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