D-Link xStack DXS-3350SR Installation & User Manual - Link Aggregation
DXS-3350SR Gigabit Layer 3 Switch
Link Aggregation
Port trunk groups are used to combine a number of ports together to make a single high-bandwidth data pipeline.
The DXS-3350SR supports up to 6 link aggreagation groups.
The Switch treats all ports in a trunk group as a single port. Data transmitted to a specific host (destination address) will
always be transmitted over the same port in a trunk group. This allows packets in a data stream to arrive in the same order
they were sent.
NOTE: If any ports within the trunk group become disconnected, packets intended for the discon-
nected port will share the load 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 8 link aggregation groups, each group consisting of 2 to 8 links (ports). The
aggregated links may be contiguous (sequential port numbers) or may be spread accross multiple switches in a stack. (An
exception applies to the two 10 Gigabit ports on the optional module which can form a link aggregation group by
themselves only). 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 Port Link
Aggregation Group table:
Figure 6- 8. Port Link Aggregation Group Entries window
To configure port trunk groups, click the Add button to add a new trunk group and use the Link Aggregation Settings
menu (see example below) to set up trunk groups. To modify a port trunk group, click the hyperlinked Group ID number
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.
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