Service Manual

Port Channel Denition and Standards
Link aggregation is dened 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 trac.
Port Channel Benets
A port channel interface provides many benets, including easy management, link redundancy, and sharing.
Port channels are transparent to network congurations and can be modied and managed as one interface. For example, you
congure one IP address for the group and that IP address is used for all routed trac 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 ve 1-Gigabit Ethernet interfaces together. If one of the ve interfaces fails, trac 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 congured.
• Dynamic — Port channels that are dynamically congured 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 congure 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 rst port channel member that is physically up. Dell Networking
OS disables the interfaces that do match the interface speed that the rst channel member sets. That rst interface may be the rst
interface that is physically brought up or was physically operating when interfaces were added to the port channel. For example, if
the rst 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 rst channel member in the port channel.
Interfaces
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