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Publication date: July, 2006
Revision A2
98
3-10. 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.