Administrator Guide

Port Channel Interfaces
Port channel interfaces support link aggregation, as described in IEEE Standard 802.3ad.
This section covers the following topics:
● Port Channel Definition and Standards
● Port Channel Benefits
● Port Channel Implementation
● Configuration Tasks for Port Channel Interfaces
Port Channel Definition and Standards
Link aggregation is defined by IEEE 802.3ad as a method of grouping multiple physical interfaces into a single logical interface—
a link aggregation group (LAG) or port channel.
A LAG is “a group of links that appear to a MAC client as if they were a single link” according to IEEE 802.3ad. In Dell
Networking OS, a LAG is referred to as a port channel interface.
A port channel provides redundancy by aggregating physical interfaces into one logical interface. If one physical interface goes
down in the port channel, another physical interface carries the traffic.
Port Channel Benefits
A port channel interface provides many benefits, including easy management, link redundancy, and sharing.
Port channels are transparent to network configurations and can be modified and managed as one interface. For example, you
configure one IP address for the group and that IP address is used for all routed traffic on the port channel.
With this feature, you can create larger-capacity interfaces by utilizing a group of lower-speed links. For example, you can build
a 5-Gigabit interface by aggregating five 1-Gigabit Ethernet interfaces together. If one of the five interfaces fails, traffic is
redistributed across the four remaining interfaces.
Port Channel Implementation
Dell Networking OS supports static and dynamic port channels.
● Static — Port channels that are statically configured.
● Dynamic — Port channels that are dynamically configured using the link aggregation control protocol (LACP). For details,
refer to Link Aggregation Control Protocol (LACP).
There are 128 port-channels with 16 members per channel.
NOTE: If you are using either 10G ports or 40G ports, the platform supports up to 16 members per LAG.
As soon as you configure a port channel, Dell Networking OS treats it like a physical interface. For example, IEEE 802.1Q tagging
is maintained while the physical interface is in the port channel.
Member ports of a LAG are added and programmed into the hardware in a predictable order based on the port ID, instead of in
the order in which the ports come up. With this implementation, load balancing yields predictable results across line card resets
and chassis reloads.
A physical interface can belong to only one port channel at a time.
Each port channel must contain interfaces of the same interface type/speed.
Port channels can contain a mix of 10, 100, or 1000 Mbps Ethernet interfaces and Gigabit Ethernet interfaces. The interface
speed (10, 100, or 1000 Mbps) the port channel uses is determined by the first port channel member that is physically up.
Dell Networking OS disables the interfaces that do match the interface speed that the first channel member sets. That first
interface may be the first interface that is physically brought up or was physically operating when interfaces were added to the
port channel. For example, if the first operational interface in the port channel is a Gigabit Ethernet interface, all interfaces at
1000 Mbps are kept up, and all 10/100/1000 interfaces that are not set to 1000 speed or auto negotiate are disabled.
Dell Networking OS brings up 10/100/1000 interfaces that are set to auto negotiate so that their speed is identical to the speed
of the first channel member in the port channel.
Interfaces
271