DES-3550 Layer 2
Fast Ethernet Switch User’s Guide
87
Note
: If any ports within the trunk group become disconnected, packets
intended for the disconnected port will be load shared among the other
uplinked ports of the link aggregation group.
Link aggregation allows several ports to be grouped together and to act as a single link. This
gives a bandwidth that is a multiple of a single link’s bandwidth.
Link aggregation is most commonly used to link a bandwidth intensive network device or
devices, such as a server, to the backbone of a network.
The Switch allows the creation of up to 6 link aggregation groups, each group consisting of 2
to 8 links (ports). The aggregated links must be contiguous (they must have sequential port
numbers) except the two (optional) Gigabit ports, which can only belong to a single link
aggregation group. All of the ports in the group must be members of the same VLAN, and
their STP status, static multicast, traffic control, traffic segmentation, and 802.1p default
priority configurations must be identical. Port locking, port mirroring, and 802.1X must not be
enabled on the trunk group. Further, the aggregated links must all be of the same speed and
should be configured as full-duplex.
The Master Port of the group is to be configured by the user, and all configuration options,
including the VLAN configuration, that can be applied to the Master Port are applied to the
entire link aggregation group.
Load balancing is automatically applied to the ports in the aggregated group, and a link failure
within the group causes the network traffic to be directed to the remaining links in the group.
The Spanning Tree Protocol will treat a link aggregation group as a single link, on the switch
level. On the port level, the STP will use the port parameters of the Master Port in the
calculation of port cost and in determining the state of the link aggregation group. If two
redundant link aggregation groups are configured on the Switch, STP will block one entire
group, in the same way STP will block a single port that has a redundant link.
To configure port trunking, click on the
Link Aggregation
hyperlink in the
Configuration
folder to bring up the
Current Link Aggregation Group Entries
table:
Figure 6- 36. Port Link Aggregation Group Entries window
To configure port trunk groups, click the
Add
button to add a new trunk group and use the
menu
Link Aggregation Group Configuration
menu (see example below) to set up trunk
groups. To modify a port trunk group, click the Modify button corresponding to the entry you
wish to alter. To delete a port trunk group, click the corresponding
under the
Delete
heading in the
Current Link Aggregation Group Entries
table.
