White Papers

Port Channel Implementation
The 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.
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 100, 1000, or 10000 Mbps Ethernet interfaces and TenGigabit Ethernet interfaces. The
interface speed (100, 1000, or 10000 Mbps) 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 Gigabit Ethernet interface, all interfaces
at 1000 Mbps are kept up, and all 100/1000/10000 interfaces that are not set to 1000 speed or auto negotiate are disabled.
100/1000/10000 Mbps Interfaces in Port Channels
When both 100/1000/10000 interfaces and TenGigabitEthernet 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 0/0, 0/1, 0/2, and 0/3) in which TenGig 0/0 and TenGig 0/3 are set to speed 100
Mb/s and the others are set to 10000 Mb/s, with all interfaces enabled, and you add them to a port channel by entering
channel-member tengigabitethernet 0/0-3 while in port channel interface mode, and the system determines if the
first interface specified (TenGig 0/0) is up. After it is up, the common speed of the port channel is 100 Mb/s. The system
disables those interfaces configured with speed 1000 Mb/s or whose speed is 1000 Mb/s as a result of auto-negotiation.
In this example, you can change the common speed of the port channel by changing its configuration so the first enabled
interface referenced in the configuration is a 1000 Mb/s speed interface. You can also change the common speed of the port
channel here by setting the speed of the TenGig 0/0 interface to 1000 Mb/s.
Configuration Tasks for Port Channel Interfaces
To configure a port channel (LAG), use the commands similar to those found in physical interfaces. By default, no port channels
are configured in the startup configuration.
These are the mandatory and optional configuration tasks:
● Creating a Port Channel (mandatory)
● Adding a Physical Interface to a Port Channel (mandatory)
● Reassigning an Interface to a New Port Channel (optional)
● Configuring the Minimum Oper Up Links in a Port Channel (optional)
● Adding or Removing a Port Channel from a VLAN (optional)
● Assigning an IP Address to a Port Channel (optional)
● Deleting or Disabling a Port Channel (optional)
344
Interfaces