FTOS Configuration Guide for the C-Series - Force10 Networks

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 FTOS, a LAG is
referred to as a port channel interface.
This logical interface provides redundancy by allowing the aggregation 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
In the E-Series, a port channel interface provides many benefits, including easy management, link
redundancy, and sharing.
Port channels are transparent to the network and can be configured 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 get larger-capacity interfaces with 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
FTOS supports two types of port channels:
• Static—Port channels that are statically configured
• Dynamic—Port channels that are dynamically configured using Link Aggregation Control Protocol
(LACP). For details on LACP, see Chapter 10, Link Aggregation Control Protocol (LACP), on page
209. .
Table 16 Number of Port-channels per Platform
Platform Port-channels Members/Channel
E-Series 255 16
C-Series 128 8
S-Series 52 8
As soon as a port channel is configured, the FTOS treats it like a physical interface. For example, the IEEE
802.1Q tagging is maintained while the physical interface is in the port channel.
As of FTOS Version 7.4.1.0, member ports of a LAG are added and programmed into 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.
256 Interfaces