Transition Networks
S4224 Web User Guide
33558 Rev. C
Page 141 of 669
Aggregation Configuration
Link aggregation (AKA trunking, link bundling, or Ethernet NIC bonding) are various methods of
combining (aggregating) multiple network connections in parallel to increase throughput over that which a
single connection could sustain, while providing redundancy in case one of the links fails.
Link aggregation addresses two Ethernet connection problems: bandwidth limitations and lack of
resilience.
The S4224 supports both Static aggregation and LACP. Note that Aggregation mismatch can occur if the
aggregation type on each end of the link does not match. Some switches do not implement the 802.1AX
standard but support static link aggregation. Link aggregation between similarly ‘statically’ configured
switches will work, but will fail between a statically configured switch and a device that is configured for
LACP.
Link aggregation bundles multiple ports (member ports) together into a single logical link. It is used mainly
to increase available bandwidth without introducing loops into the network, and to improve resilience
against faults. A link aggregation group (LAG) can be established with individual links being dynamically
added or removed. This enables bandwidth to be incrementally scaled based on changing requirements.
A LAG can be quickly reconfigured if faults are identified.
Frames destined for a LAG are sent on only one of the LAGs member ports. The member port on which a
frame is forwarded is determined by a 4-bit aggregation code (AC) that is calculated for the frame.
The aggregation code ensures that frames belonging to the same frame flow (e.g., a TCP connection) are
always forwarded on the same LAG member port. For that reason, reordering of frames within a flow is
not possible. The AC is based on the following information:
1. SMAC (Source MAC address)
2. DMAC (Destination MAC address)
3. Source and Destination IPv4 address
4. Source and Destination TCP/UDP ports for IPv4 packets
5. Source and Destination TCP/UDP ports for IPv6 packets
6. IPv6 Flow Label
For best traffic distribution among LAG member ports, enable all six contributions to the AC.
Each LAG can consist of up to 16 member ports. Any quantity of LAGs may be configured for the S4224
(only limited by the number of device ports). To configure a proper traffic distribution, the ports within a
LAG must use the same link speed.
A port cannot be a member of multiple LAGs.
The Aggregation Configuration parameters are explained below.
