Using Link Aggregation (Etherchannel) To External Networks; Etherchannel And Link Aggregation - IBM p5 590 System Handbook

3.4.2 Using Link Aggregation (EtherChannel) to external networks

Link aggregation is network port aggregation technology that allows several
Ethernet adapters to be aggregated together to form a single pseudo Ethernet
device. This technology can be used to overcome the bandwidth limitation of a
single network adapter and avoid bottlenecks when sharing one network adapter
amongst many client partitions.
For example, ent0 and ent1 can be aggregated to ent3. Interface en3 would then
be configured with an IP address. The system considers these aggregated
adapters as one adapter. Therefore, IP is configured as on any other Ethernet
adapter. In addition, all adapters in the link aggregation are given the same
hardware (MAC) address, so they are treated by remote systems as though they
were one adapter. The main benefit of link aggregation is that they have the
network bandwidth of all of their adapters in a single network presence. If an
adapter fails, the packets are automatically sent on the next available adapter
without disruption to existing user connections. The adapter is automatically
returned to service on the link aggregation when it recovers.
You can use EtherChannel or IEEE 802.3ad Link Aggregation to aggregate
network adapters. While EtherChannel is an AIX 5L Version 5.3 specific
implementation of adapter aggregation, Link Aggregation follows the IEEE
802.3ad standard. Table 3-4 shows the main differences between EtherChannel
and Link Aggregation.
Table 3-4 EtherChannel and Link Aggregation
EtherChannel
Requires switch configuration
Supports different packet distribution
modes
The main benefit of using Link Aggregation is, that if the switch supports the
Aggregation Control Protocol
is required. The benefit of EtherChannel is the support of different packet
distribution modes. This means it is possible to influence the load balancing of
the aggregated adapters. In the remainder of this document, we will use Link
Aggregation where possible since that is considered a more universally
understood term.
Note: Only outgoing packets are subject to the following discussion, incoming
packets are distributed by the Ethernet switch.
IEEE 802.3ad Link Aggregation
Little, if any, configuration of switch
required to form aggregation. Some initial
setup of the switch may be required.
Supports only standard distribution mode
(LACP) no special configuration of the switch ports
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