I. Product Setup Guides

Link Aggregation between two G1241 switches

Products:
VigorSwitch G1241
Keywords:
LACP
LAG
Link Aggregation
Trunk

DrayTek VigorSwitches that support 802.3ad Link Aggregation can have several of their ports linked together from one switch to the next, to allow for higher combined throughput and redundancy.

Link Aggregation combines several physical ports into one logical port which offer a higher combined bandwidth, although any single session can only utilise one port so there is a limit on the per-session transfer rate imposed by the data rate of a single port.

For example if PC-A on the first switch is communicating with PC-B on the second switch, and PC-C on the first switch is communicating with PC-D on the second switch, in a standard scenario with just one link between the two switches, both sessions would share the same single 1Gbps link. If alternatively Link Aggregtation is employed and the two switches are linked together with additional ports, the two sessions would likely be able to use a different link so that each individually is able to use a 1Gb/s link. Having multiple ports connected between the two switches reduces the bottleneck of a single link. Each link would allow us to transfer packets with up to 1Gb/s throughput.

We will need the following equipment to set up a Link Aggregation Group (LAG) with VigorSwitch G1241 switches:

  • Two G1241 switches
  • Two (up to 8) available Ethernet ports to link the switches

NOTE: Do NOT link the switches with more than one physical cable at this stage to avoid a network loop.


Navigate to [Switching] >> [Link Aggregation] >> [LAG Setting] to select the load balance algorithm.

  • MAC Address algorithm is based on source and destination MAC address for all packets
  • IP-MAC Address algorithm is based on on source and destination IP addresses for IP packet, and source and destination MAC address for non-IP packets.



Then navigate to [LAG Management], select a group, for example LAG 1. Click Edit, a new page should be displayed where the physical ports are to be selected.

There are the following limitations when selecting the member ports:

  • All ports in a LAG (Link Aggregation Group) must be of the same media type (either RJ-45 or SFP).
  • To add a port to the LAG, it cannot belong to any VLAN except the default VLAN.
  • Ports in a LAG must not be assigned to another LAG.
  • Ports in a LAG must not be a mirroring port.
  • No more than eight ports are assigned to a LAG.
  • When a port is added to a LAG, the configuration of the LAG is applied to the port. When the port is removed from the LAG, its original configuration is reapplied.

In the below example, the link aggregation ports are 23 and 24.


In the [Switching] >> [Link Aggregation] >> [LAG Port Setting] section the speed negotiation can be configured if needed.


Default settings such as State: Enabled, Speed: Auto, Flow Control: Disable are recommended.

The [Switching] >> [Link Aggregation] >> [LACP Setting] section allows to define Port Priority - the default value is recommended.


In the last section of the Link Aggregation the timeout to keep alive mechanism for link member can be selected;

  • Long(30s)
  • Short(1s)

Once the configuration is completed on the switches, connect additional Ethernet cables to the correct port. If you have noticed that all lights on the switch are blinking rapidly at the same time (broadcast storm), or the network is down, unplug the Ethernet cable and check that the correct ports are configured and linked together.

Saving Configuration

Changes made to the switch configuration are not automatically saved and must be manually saved so that the settings continue to apply if the switch is power cycled or restarted.

Always remember to save the configuration before Logout.

Go to the [Maintenance >> Configuration Manager], and select 'Running Configuration'


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