Link aggregation
You can configure a network interface that is the bundle of several physical links via either the web UI or the CLI.
Link aggregation (also called NIC teaming/bonding or link bundling) forms a network interface that queues and transmits over multiple wires (also called a port channel), instead of only a single wire (as FortiADC would normally do with a single network interface per physical port). This multiplies the bandwidth that is available to the network interface, and therefore is useful if FortiADC will be inline with your network backbone.
Link aggregation on FortiADC complies with
IEEE 802.3ad and distributes Ethernet frames using a modified round-robin behavior. If a port in the aggregate fails, traffic is redistributed automatically to the remaining ports with the only noticeable effect being a reduced bandwidth. When broadcast or multicast traffic is received on a port in the aggregate, reverse traffic will return on the same port.
When link aggregation uses a round-robin that considers only Layer 2, Ethernet frames that comprise an HTTP request can sometimes arrive out of order. Because network protocols at higher layers often do not gracefully handle this (especially TCP, which may decrease network performance by requesting retransmission when the expected segment does not arrive), FortiADC’s frame distribution algorithm is configurable.
For example, if you notice that performance with link aggregation is not as high as you expect, you could try configuring FortiADC to queue related frames consistently to the same port by considering the IP session (Layer 3) and TCP connection (Layer 4), not simply the MAC address (Layer 2).
You must also configure the router, switch, or other link aggregation control protocol (LACP)-compatible device at the other end of FortiADC’s network cables to match, with identical:
• link speed
• duplex/simplex setting
• ports that can be aggregated
This will allow the two devices to use the cables between those ports to form a trunk, not an accidental Layer 2 (link) network loop. FortiADC will use LACP to:
• detect suitable links between itself and the other device, and form a single logical link
• detect individual port failure so that the aggregate can redistribute queuing to avoid a failed port
To configure a link aggregate via the CLI
1. Enter the following commands:
config system interface
edit "aggregate"
set type agg
set aggregate-mode {802.3ad | balance-alb | balance-rr | balance-tlb | balance-xor | broadcast}
set aggregate-algorithm {layer2 | layer2_3 | layer3_4}
set status up
set redundant-member <port_name> <port_name>
set ip <address_ipv4/mask>
next
end
where:
• {802.3ad | balance-alb | balance-rr | balance-tlb | balance-xor | broadcast} is a choice of link aggregation type
• {layer2 | layer2_3 | layer3_4} is a choice between the connectivity layers that will be considered when distributing frames among the aggregated physical ports
• <port_name> is the name of a physical network interface that will belong to the aggregate, such as port3
• <address_ipv4/mask> is the IP address assigned to the network interface and its netmask in CIDR format
See also