Reference Guide
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 the 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 30-Gigabit interface by aggregating three 10-Gigabit Ethernet interfaces together. If one of the five interfaces fails, traffic is
redistributed across the four remaining interfaces.
Port Channel Implementation
The system 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).
Up to 128 port- channels with sixteen 10GbE or 40GbE port members per channel are supported.
As soon as you configure a port channel, the system 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 or 40 Gigabit Ethernet interfaces. The interface speed (10, 40 Gbps) the port channel
uses is determined by the first port channel member that is physically up. The system 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 10–Gigabit Ethernet interface, all interfaces at 40Gbps are kept up, and all 10/40 GbE interfaces that are not
set to 1000 speed or auto negotiate are disabled.
The system brings up 10/40 GbE 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.
10/40 Gbps Interfaces in Port Channels
When both 10/40 interfaces GigE interfaces are added to a port channel, the interfaces must share a common speed. When
interfaces have a configured speed different from the port channel speed, the software disables those interfaces.
The common speed is determined when the port channel is first enabled. At that time, the software checks the first interface
listed in the port channel configuration. If you enabled that interface, its speed configuration becomes the common speed of the
port channel. If the other interfaces configured in that port channel are configured with a different speed, the system disables
them.
For example, if four interfaces (TenGig 0/1, 0/2, 0/3 and 0/4) in which TenGig 0/1 and TenGig 0/2 are set to speed 10 Gb/s
and the others(te 0/3 and 0/4) are set to 40 Gb/s, with all interfaces enabled, and you add them to a port channel by entering
channel-member tengigabitethernet 0/1-4 while in port channel interface mode, and the system determines if the
Interfaces
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