Allied Telesis AT-S62 - Manual (Page 144)

Chapter 8: Static and LACP Port Trunks
144 Section I: Basic Operations
device. If it does not receive LACPDU packets, it functions as a regular
Ethernet port, forwarding network traffic while also continuing to
transmit LACPDU packets.
ˆ The port with the highest priority in an aggregate trunk carries
broadcast packets and packets with an unknown destination.
ˆ Prior to creating an aggregate trunk between an AT-8500 Series
switch and another vendor’s device, refer to the vendor’s
documentation to determine the maximum number of active ports the
device can support in a trunk. If the number is less than eight, the
maximum number for the AT-8500 Series switch, you should probably
assign it a higher system LACP priority than the AT-8500 Series
switch. If it is more than eight, assign the AT-8500 Series switch the
higher priority. This can help avoid a possible conflict between the
devices if some ports are placed in the standby mode when the trunk
is created by the devices. For background information, refer to “LACP
System Priority” on page 141.
ˆ LACPDU packets are transmitted as untagged packets.
Load Distribution
Methods
This section discusses the load distribution methods and applies to both
static and LACP port trunks.
One of the steps to creating a static or LACP port trunk is the selection of
a load distribution method. This step determines how the switch distributes
the traffic load across the ports in the trunk. The AT-S62 management
software offers the following load distribution methods:
ˆ Source MAC Address (Layer 2)
ˆ Destination MAC Address (Layer 2)
ˆ Source MAC Address / Destination MAC Address (Layer 2)
ˆ Source IP Address (Layer 3)
ˆ Destination IP Address (Layer 3)
ˆ Source IP Address / Destination IP Address (Layer 3)
The load distribution methods examine the last three bits of a packet’s
MAC or IP address and compare the bits against mappings assigned to
the ports in the trunk. The port mapped to the matching bits is selected as
the transmission port for the packet.
In cases where you select a load distribution that employs either a source
or destination address but not both, the last three bits of only the
designated address are used in the selection of a transmission port in a
trunk. If you select one of the two load distribution methods that employs
both source and destination addresses, port selection is achieved through
an XOR operation of the last three bits of both addresses.