Subnet Based Vlans - ZyXEL Communications MGS-3712/MES-3728 User Manual

9.6 Subnet Based VLANs

Subnet based VLANs allow you to group traffic into logical VLANs based on the
source IP subnet you specify. When a frame is received on a port, the Switch
checks if a tag is added already and the IP subnet it came from. The untagged
packets from the same IP subnet are then placed in the same subnet based VLAN.
One advantage of using subnet based VLANs is that priority can be assigned to
traffic from the same IP subnet.
For example, an ISP (Internet Services Provider) may divide different types of
services it provides to customers into different IP subnets. Traffic for voice
services is designated for IP subnet 172.16.1.0/24, video for 192.168.1.0/24 and
data for 10.1.1.0/24. The Switch can then be configured to group incoming traffic
based on the source IP subnet of incoming frames.
You configure a subnet based VLAN with priority 6 and VID of 100 for traffic
received from IP subnet 172.16.1.0/24 (voice services). You also have a subnet
based VLAN with priority 5 and VID of 200 for traffic received from IP subnet
192.168.1.0/24 (video services). Lastly, you configure VLAN with priority 3 and
VID of 300 for traffic received from IP subnet 10.1.1.0/24 (data services). All
untagged incoming frames will be classified based on their source IP subnet and
prioritized accordingly. That is video services receive the highest priority and data
the lowest.
Figure 51 Subnet Based VLAN Application Example
172.16.1.0/24
VID = 100
MES-3728 User's Guide
Tagged Frames
Untagged
Frames
10.1.1.0/24
192.168.1.0/24
VID = 300
VID = 200
Chapter 9 VLAN
Internet
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