Chapter 12 port channel configuration, 1 introduction to port channel, Chapter 12 port channel configuration -1 – PLANET XGS3-24042 User Manual

Page 109: Ntroduction to, Hannel

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Chapter 12 Port Channel Configuration

12.1 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.

Figure 12-1 Port aggregation

As shown in the above, S1 is aggregated to a Port Channel, the bandwidth of this Port Channel is the total of

all the four ports. If traffic from S1 needs to be transferred to S2 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.

Switch offers two 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 Channel to work properly, member ports of the Port Channel must have the same properties as

follows:

 All ports are in full-duplex mode.
 All Ports are of the same speed.
 All ports are Access ports and belong to the same VLAN or are all TRUNK ports, or are all Hybrid ports.
 If the ports are all TRUNK ports or Hybrid ports , then their “Allowed VLAN” and “Native VLAN” property

S1

S2

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