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DCS-3950 series Ethernet switch manual
Chapter 17 Port Channel Configuration
17.1 Introduction to Port Channel
To understand Port Channel, Port Group should be introduced first. Port Group is a
group of physical ports in the configuration level; only physical ports in the Port Group can
take part in link aggregation and become a member port of a Port Channel. Logically, Port
Group is not a port but a port sequence. Under certain conditions, physical ports in a Port
Group perform port aggregation to form a Port Channel that has all the properties of a
logical port, therefore it becomes an independent logical port. Port aggregation is a
process of logical abstraction to abstract a set of ports (port sequence) with the same
properties to a logical port. Port Channel is a collection of physical ports and used logically
as one physical port. Port Channel can be used as a normal port by the user, and can not
only add network’s bandwidth, but also provide link backup. Port aggregation is usually
used when the switch is connected to routers, PCs or other switches.
Fig 17-1 Port aggregation
As shown in the above figure, Switch1 is aggregated to a Port Channel, the
bandwidth of this Port Channel is the total of all the four ports. If traffic from SwitchA needs
to be transferred to SwitchB through the Port Channel, traffic allocation calculation will be
performed based on the source MAC address and the lowest bit of target MAC address.
The calculation result will decide which port to convey the traffic. If a port in Port Channel
fails, the other ports will undertake traffic of that port through a traffic allocation algorithm.
This algorithm is carried out by the hardware.
DCS-3950 series switch offers 2 methods for configuring port aggregation: manual
Port Channel creation and LACP (Link Aggregation Control Protocol) dynamic Port
Channel creation. Port aggregation can only be performed on ports in full-duplex mode.
For Port Chansnel to work properly, member ports of the Port Channel must have the
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