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4.16 Trunking Configuration
The Port Trunking Configuration is used to configure the settings of Link Aggregation. You can bundle more
than one port with the same speed, full duplex and the same MAC to be a single logical port, thus the logical
port aggregates the bandwidth of these ports. This means you can apply your current Ethernet equipments to
build the bandwidth aggregation. For example, if there are three Fast Ethernet ports aggregated in a logical
port, then this logical port has bandwidth three times as high as a single Fast Ethernet port has.
The switch supports two kinds of port trunking methods:
LACP
Ports using Link Aggregation Control Protocol (according to IEEE 802.3ad specification) as their trunking
method can choose their unique LACP GroupID (1~3) to form a logic "trunked port". The benefit of using
LACP is that a port makes an agreement with its peer port before it becomes a ready member of a "trunk
group" (also called aggregator). LACP is safer than the other trunking method - static trunk.
The switch LACP does not support the followings:
- Link Aggregation across switches
- Aggregation with non-IEEE 802.3 MAC link
- Operating in half-duplex mode
- Aggregate the ports with different data rates
Static Trunk
Ports using Static Trunk as their trunk method can choose their unique Static GroupID (also 1~3, this Static
groupID can be the same with another LACP groupID) to form a logic trunked port. The benefit of using
Static Trunk method is that a port can immediately become a member of a trunk group without any
handshaking with its peer port. This is also a disadvantage because the peer ports of your static trunk group
may not know that they should be aggregate together to form a logic trunked port. Using Static Trunk on both
end of a link is strongly recommended. Please also note that low speed links will stay in "not ready" state when
using static trunk to aggregate with high speed links.
As to system restrictions about the port aggregation function on the switch, in the management point of view,
the switch supports maximum 3 trunk groups for LACP and additional 3 trunk groups for Static Trunk. But in
the system capability view, only 3 real trunked groups are supported. An LACP trunk group with more than one
ready member-ports is a real trunked group. An LACP trunk group with only one or less than one ready
member-ports is not a real trunked group. Any Static trunk group is a real trunked group.
Per Trunking Group supports a maximum of 12 ready member-ports. Please note that some decisions will
automatically be made by the system while you are configuring your trunking ports. Some configuration
examples are listed below.
Rule 1: 12 ports have already used Static Trunk Group ID 1, the 13th port willing to use the same Static
Trunk Group ID will be automatically set to use the "None" trunking method and its Group ID will
turn to 0. This means the port won't aggregate with other ports.
Rule 2: 14 ports all use LACP Trunk Group ID 1 at most 12 ports can aggregate together and transit into
the ready state.
Rule 3: A port using the "None" trunking method or Group ID 0 will be automatically set to use the "None"
trunking method with Group ID 0.
CHAPTER 4: Web-Based Management
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