3Com Switch 7750 Configuration Guide

14
SUPER VLAN
n
Only the 96Gbps switch fabrics support the super VLAN.
Super VLAN Overview To save IP address resources, the super VLAN concept (also known as VLAN
aggregation) was developed. Its principle is like this: a super VLAN may include
multiple sub VLANs, with each as a broadcast domain. Layer 2 isolation is
implemented between sub VLANs. The super VLAN can be configured with a Layer
3 interface, but not the sub VLAN.
When users in different sub VLANs want Layer 3 communication, they use the IP
address of the Layer 3 interface of the super VLAN as their gateway address. IP
address resources are saved since multiple sub VLANs share one IP address.
At the same time, in order to realize the Layer 3 connectivity between the sub
VLANs and between the sub VLAN and other networks, ARP proxy function is
used. ARP proxy enables Layer 3 connectivity between Layer 2 isolated ports by
performing ARP request and forwarding and handling response packets.
Super VLAN
Configuration
Super VLAN
Configuration Tasks
Configuring a Super
VLAN
You can configure multiple super VLANs for a switch. You can use the following
commands to specify a VLAN as a super VLAN. After a VLAN is configured as a
super VLAN, the configuration of corresponding VLAN interfaces and IP addresses
is the same as the configuration for an ordinary VLAN.
Table 68 Super VLAN configuration tasks
Operation Description Related section
Configure a super VLAN Optional “Configuring a Super VLAN”
on page 121
Configure a sub VLAN Optional “Configuring a Sub VLAN” on
page 122
Configure the mapping
between super VLAN and sub
VLAN
Optional “Configuring the Mapping
between a Super VLAN and a
Sub VLAN” on page 122
Configure super VLAN to
support DHCP relay
Optional “Configuring Super VLAN to
Support DHCP Relay” on page
123