Proware 3164S1/D1-G1S3, User Manual

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iSCSI GbE to SAS/SATA II RAID Subsystem
User Manual 119
6.9 Trunking and LACP
Link aggregation is the technique of taking several distinct Ethernet links to let them
appear as a single link. It has a larger bandwidth and provides the fault tolerance ability.
Beside the advantage of wide bandwidth, the I/O traffic remains operating until all
physical links fail. If any link is restored, it will be added to the link group automatically.
The iSCSI subsystem implements link aggregation as LACP and Trunking.
1.
LACP (IEEE 802.3ad): The Link Aggregation Control Protocol (LACP) is a part of
IEEE specification 802.3ad. It allows bundling several physical ports together to
form a single logical channel. A network switch negotiates an automatic bundle by
sending LACP packets to the peer. Theoretically, LACP port can be defined as active
or passive. iSCSI controller implements it as active mode which means that LACP
port sends LACP protocol packets automatically. Please notice that using the same
configurations between iSCSI controller and gigabit switch.
The usage occasion of LACP:
A. It’s necessary to use LACP in a network environment of multiple switches. When
adding new devices, LACP will separate the traffic to each path dynamically.
2.
Trunking (Non-protocol): Defines the usage of multiple iSCSI data ports in
parallel to increase the link speed beyond the limits of any single port.
The usage occasion of Trunking:
A. This is a simple SAN environment. There is only one switch to connect the
server and storage. And there is no extra server to be added in the future.
B. There is no idea of using LACP or Trunking, uses Trunking first.
C. There is a request of monitoring the traffic on a trunk in switch.