Citrix SD-WAN

Link Aggregation Groups

The Link Aggregation Groups (LAG) functionality allows you to group two or more ports on your SD-WAN appliance to work together as a single port. This ensures increased availability, link redundancy, and enhanced performance.

Earlier, only the Active-Backup mode was supported in LAG. From 11.3 release onwards, the 802.3AD Link Aggregation Control Protocol (LACP) protocol based negotiations are supported. The LACP is a standard protocol and provides more functionality for LAGs.

In Active-Backup mode, at any time only one port is active and the other ports are in backup mode. The active and backup supports rely on the Data Plane Development Kit (DPDK) package for LAG functionality.

With the LACP, you can send the traffic through all the ports simultaneously. As a benefit, you get more bandwidth along with the link redundancy mechanism. The LACP implementation supports the Active-Active mode. Now with the Active-Backup mode, you also have an option to select full LACP Active-Active mode from the SD-WAN UI.

The LAG functionality is available only on the following DPDK supported platforms:

  • Citrix SD-WAN 110 SE
  • Citrix SD-WAN 210 SE
  • Citrix SD-WAN 410 SE
  • Citrix SD-WAN 1100 SE/PE
  • Citrix SD-WAN 4000, 4100, and 5100 SE
  • Citrix SD-WAN 6100 SE
  • Citrix SD-WAN 2100 SE

Note

The LAG functionality is not supported on VPX/VPXL platforms.

Limitations

  • You can create a maximum of 4 LAGs with a maximum of 4 ports grouped in each LAG on the Citrix SD-WAN appliances.

  • The port priority and system priority options are not supported with the LACP implementation.

With 11.3 release onwards, in SD-WAN with the LACP implementation, the ports are always in active mode. That means SD-WAN can always start the negotiation.

Note

For Citrix SD-WAN 210 and 410 appliances, you can create a maximum of 3 LAGs with a maximum of 4 ports grouped in each LAG.

To configure Link aggregation groups, in the Configuration Editor, navigate to Sites > Link Aggregation Groups. You can view all the available physical ports and Ethernet interfaces. Click + to create a LAG.

Add link aggregation groups

Select the member ports, and click Apply. Once the ports are added to the LAG, you can see only the LAGs in the Interface Group instead of the member ports.

Interface groups

Similarly, if you want to configure the LAGs with LACP mode:

  1. Click + to create a LAG and select the Ethernet interface ports.
  2. Select configuration mode as LACP from the drop-down list.
  3. Select the Transmission Policy from the drop-down list.

    NOTE

    If the mode is selected as Active-Backup, the Transmission Policy field gets disabled.

  4. Click Apply.

    LACP

As LAG groups have many ports, the Transmission Policy helps to select the port that can be used to send traffic. The transmission policy field can be enabled only if the Aggregation mode is Active-Active. There are two transmission policies defined – MAC+IP and IP+L4.

  • MAC+IP: The link selection for a given packet is based on the layer 2 and 3 parameters. So the source and destination MAC and IP addresses take these parameters and hash them. According to hash, it selects the port.

  • IP+L4: The IP+L4 policy is based on the source and destination IP and layer 4 ports and protocol. The IP+L4 policy notifies which packet is going through which port. Packet with the same parameters will always be sent on one of the links. That means, the same or single flow (same source and destination Mac and IP) always goes through the same ports and not distributes across the other ports. As a benefit, the out of order packets cannot reach to the destination device

You can create virtual interfaces using LAGs and these interfaces are further used to configure LAN/WAN links and HA.

Note

The Link State Propagation (LSP) feature is not supported, if LAGs are used as Ethernet interfaces in Interface Groups.

Monitoring and Troubleshooting

To view the statistics or the link state, navigate to Monitoring > Statistics. Select Ethernet from the Show drop-down list.

LAG statistics

To view the active and standby LAG ports, navigate to Configuration > Appliance Settings > Network Adapters > Ethernet.

LAG port details

Select the LACP LAG Group tab to view the various details related to the LACP LAG group.

LACP LAG group

Note

You cannot change settings for individual member ports, any configuration changes made to the LAG, is automatically pushed to the member ports.

You can download the log files for further troubleshooting. Navigate to Configuration > Logging/Monitoring and select SDWAN_common.log from the Log Options tab.

Log file

Link Aggregation Groups