Link Aggregation
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A Link Aggregation Group (LAG) optimizes port usage by linking a group of ports together to form a single, logical, higher-bandwidth link. Aggregating ports multiplies the bandwidth and increases port flexibility for the switch. Link Aggregation is most used to link a bandwidth intensive network device (or devices), such as a server, to the backbone of a network.
The participating ports are called members of a port trunk group. Since all ports of the trunk group must be configured to operate in the same manner, the configuration of one port of the trunk group is applied to all ports of the trunk group. Thus, you will only need to configure one of any of the ports in a trunk group. A specific data communication packet will always be transmitted over the same port in a trunk group. This ensures the delivery of individual frames of a data communication packet will be received in the correct order. The traffic load of the LAG will be balanced among the ports according to aggregate arithmetic. If the connections of one or several ports are broken, the traffic of these ports will be transmitted on the normal ports to guarantee reliable connection.
When you aggregate ports, the ports and LAG must fulfill the following conditions:
All ports within a LAG must be the same media/format type.
A VLAN is not configured on the port.
The port is not assigned to another LAG.
The Auto-negotiation mode is not configured on the port.
The port is in full-duplex mode.
All ports in the LAG have the same ingress filtering and tagged modes.
All ports in the LAG have the same back pressure and flow control modes.
All ports in the LAG have the same priority.
All ports in the LAG have the same transceiver type.
Ports can be configured as LACP ports only if the ports are not part of a previously configured LAG.
LACP is a dynamic protocol which helps to automate the configuration and maintenance of LAGs. The main purpose of LACP is to automatically configure individual links to an aggregate bundle, while adding new links and helping to recover from link failures if the need arises. LACP can monitor to verify if all the links are connected to the authorized group. LACP is a standard in computer networking; hence, LACP should be enabled on the switch's trunk ports initially for both the participating switches/devices that support the standard, to use it.
Port trunking allows you to assign physical links to one logical link that functions as a single, higher-speed link, providing dramatically increased bandwidth. Use port trunking to bundle multiple connections and use the combined bandwidth as if it were a single larger “pipe.”
Important: You must enable Trunk Mode before you can add a port to a trunk group.
Item | Description |
Group | Displays the number of the given trunk group. You can utilize up to 8 link aggregation groups with each group consisting up to 8 ports on the switch. |
Active Ports | Displays the active participating members of the trunk group. |
Member Port | Select the ports you wish to add to the trunk group. Up to eight ports per group can be assigned. Static: The Link Aggregation is configured manually for specified trunk group. LACP: The Link Aggregation is configured dynamically for specified trunk group. |
Mode | LACP allows for the automatic detection of links in a port trunking group when connected to a LACP-compliant switch. You will need to ensure that both the switch and the device it’s connected to are in the same mode for them to function; otherwise, they will not work. Static configuration is used when connecting to a switch that does not support LACP. |
Assign a system priority to run with Link Aggregation Control Protocol (LACP), which will become a backup link if another link goes down. The lowest system priority can make decisions about which ports it is actively running in case a link goes down. If two or more ports have the same LACP port priority, the port with the lowest physical port number will be selected as the backup port. If a LAG already exists with the maximum number of allowed port members, and LACP is subsequently enabled on another port using a higher priority than an existing member, the newly configured port will replace the existing port member that has a lower priority. A smaller number indicates a higher priority level. The range is from 0-65535 and default is 32768.
Click Apply to save settings.
Item | Description |
System Priority | Enter the LACP priority value to the system. The default is 32768 and the range is from 1 to 65535. |
System Policy | Select the system policy from the drop-down list. |
Link Aggregation Control Protocol (LACP) allows the exchange of information regarding the link aggregation between two members of the aggregation. The LACP Time Out value is measured in a periodic interval. Check first whether the port in the trunk group is up. When the interval expires, it will be removed from the trunk. Set a Short Timeout (one second) for busy trunked links to ensure that disabled ports are removed from the trunk group as soon as possible. The default value for LACP time out is Long Timeout.
Item | Description |
Timeout | Select the administrative LACP timeout. Long Timeout: The LACP PDU will be sent for every 30 seconds. The LACP timeout value is 90 seconds. Short Timeout: The LACP PDU will be sent every second. The timeout value is 3 seconds. |
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