ATL Telecom R1-SW Ethernet Switch - Manual (Page 250)

R1-SW24L2B User’s Manual
12-2
LACP (Link Aggregation Control Protocol)
In the Corecess R1-SW24L2B, several physical links can be configured to single logical link to
connect backbone devices that request high bandwidth or to connect networks that bottle neck
of traffic might occur. This feature is called port trunking or link aggregation, and the group of
port in the same trunk is called trunk group. The one logical port supports the same amount of
bandwidth as the total amount of bandwidth that adds each physical port.
For example, the maximum bandwidth of the port that connects the system A and the system B
is 1Gbps, but the amount of data that receives and transmits between two systems can exceed
1Gbps. In this case, it is considered that several ports are connected between two systems. But,
if there are several connections (links) between systems, only one link is used automatically by
STP protocol because a loop can occur. If STP protocol is not used to prevent this situation,
communication might not operate because loops can not be detected.
Port trunking can be used in the case. Several ports act as single port, so it can be easily
managed by VLAN, STP and IGMP. Port trunking also effects stability of the system. Even if
some ports that are included in a trunking group are not operating normally, communication
can be continued by rest ports.
In the Corecess R1-SW24L2B, port trunking can be implemented by 802.ad link aggregation,
and 802.3ad link aggregation uses LACP (Link Aggregation Control Protocol). LACP allows
ports that have the same link aggregation key value to configure themselves into a trunking
group.