Administrator Guide

Port Channel Implementation
The 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.
As soon as you congure 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 rst port channel member that is physically up. The
system 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
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 congured speed dierent from the port channel speed, the software disables those
interfaces.
The common speed is determined when the port channel is rst enabled. At that time, the software checks the rst interface listed
in the port channel conguration. If you enabled that interface, its speed conguration becomes the common speed of the port
channel. If the other interfaces congured in that port channel are congured with a dierent 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 rst interface specied
(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
congured 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 conguration so the rst enabled interface
referenced in the conguration 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.
Conguration Tasks for Port Channel Interfaces
To congure a port channel (LAG), use the commands similar to those found in physical interfaces. By default, no port channels are
congured in the startup conguration.
These are the mandatory and optional conguration tasks:
• Creating a Port Channel (mandatory)
• Adding a Physical Interface to a Port Channel (mandatory)
• Reassigning an Interface to a New Port Channel (optional)
Interfaces
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