Port Trunking; Vlans & Mac-Based Broadcast Domains - D-Link DES-3624 Series User Manual

Stackable NWay Ethernet Switch User's Guide

Port Trunking

Port trunking is used to combine a number of ports together to make a single high-bandwidth data pipeline.
The participating parts are called members of a trunk group, with one port designated as the anchor of the
group. Since all members of the trunk group must be configured to operate in the same manner, all settings
changes made to the anchor port are applied to all members of the trunk group. Thus, when configuring the
ports in a trunk group, you only need to configure the anchor port.
The Switch supports 3 trunk groups, which may include from 2 to 8 switch ports each, except for the third
trunk group which consists of the 2 ports of the Slot 1, 100BASE-TX or 100BASE-FX front-panel module. The
anchor port for the first group is preset as port 5, the anchor port for the second group is port 13 and the
anchor port for the third group is the first port (1x) on the 2-port module.
Figure 5-3. Port trunking example
The switch treats all ports in a trunk group as a single port. As such, trunk ports will not be blocked by
Spanning Tree (unless a redundant link with higher STP priority is present).
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. A trunk
connection can be made with any other switch that maintains host-to-host data streams over a single trunk
port. A trunk connection cannot be made with switches that perform load-balancing on a per-packet basis.
VLANs & MAC-Based Broadcast Domains
VLANs are a collection of users or switch ports grouped together in a secure, autonomous broadcast and
multicast domain. The main purpose of setting up VLANs or a broadcast domain on a network is to limit the
range and effects of broadcast packets.
Two types of VLANs are implemented on the Switch: 802.1Q VLANs and port-based VLANs. MAC-based
broadcast domains are a third option. Only one type of VLAN or broadcast domain can be active on the Switch
at any given time, however. Thus, you will need to choose the type of VLAN or broadcast domain you wish to
36 Switch Management Concepts