3Com Switch 7750 Configuration Guide Guide

21
PORT BASIC CONFIGURATION
Ethernet Port
Overview
Link Types of Ethernet
Ports
An Ethernet port on a Switch 7750 Family can operate in one of the three link
types:
■ Access: An access port can belong to only one VLAN, and is generally used to
connect user PCs.
■ Trunk: A trunk port can belong to more than one VLAN. It can receive/send
packets from/to multiple VLANs, and is generally used to connect another
switch.
■ Hybrid: A hybrid port can belong to more than one VLAN. It can receive/send
packets from/to multiple VLANs, and can be used to connect either a switch or
user PCs.
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A hybrid port allows the packets of multiple VLANs to be sent without tags, but a
trunk port only allows the packets of the default VLAN to be sent without tags.
You can configure all the three types of ports on the same device. However, note
that you cannot directly switch a port between trunk and hybrid and you must set
the port as access before the switching. For example, to change a trunk port to
hybrid, you must first set it as access and then hybrid.
Configuring the Default
VLAN ID for a Port
An access port can belong to only one VLAN. Therefore, the VLAN an access port
belongs to is also the default VLAN of the access port. A hybrid/trunk port can
belong to several VLANs, and so a default VLAN ID for the port is required.
After you configure default VLAN IDs for Ethernet ports, the packets passing
through the ports are processed in different ways depending on different
situations. See
Table 95 for details.