Subnet plan · 802.1Q · trunk config
VLAN Calculator
Plan VLAN subnets, validate 802.1Q VLAN IDs, compute the tag and generate ready-to-paste trunk configuration.
VLAN subnet planner
Carve a base network into per-VLAN subnets.
| VLAN | Name | Subnet | Range | Gateway | Broadcast | Hosts | Type |
|---|---|---|---|---|---|---|---|
| 10 | VLAN10 | 10.0.0.0/18 | 10.0.0.1 – 10.0.63.254 | 10.0.0.1 | 10.0.63.255 | 16,382 | Normal |
| 11 | VLAN11 | 10.0.64.0/18 | 10.0.64.1 – 10.0.127.254 | 10.0.64.1 | 10.0.127.255 | 16,382 | Normal |
| 12 | VLAN12 | 10.0.128.0/18 | 10.0.128.1 – 10.0.191.254 | 10.0.128.1 | 10.0.191.255 | 16,382 | Normal |
| 13 | VLAN13 | 10.0.192.0/18 | 10.0.192.1 – 10.0.255.254 | 10.0.192.1 | 10.0.255.255 | 16,382 | Normal |
VLAN ID lookup
Classify a VLAN ID (1-4094).
Range
2–1001
Type
Normal
VTP
All modes
Valid
Yes
Standard user VLANs, stored in vlan.dat
802.1Q TCI calculator
Build the Tag Control Information field.
000
0
000001100100
TPID 0x8100 + TCI = the 4-byte 802.1Q tag.
Trunk config builder
Generate switch trunk configuration.
interface GigabitEthernet0/1 switchport trunk encapsulation dot1q switchport mode trunk switchport trunk native vlan 1 switchport trunk allowed vlan 10-20,30 !
| Range | Type | Count | VTP |
|---|---|---|---|
| 1 | Default | 1 | All modes |
| 2–1001 | Normal | 1000 | All modes |
| 1002–1005 | Reserved | 4 | All modes |
| 1006–4094 | Extended | 3089 | Transparent / Off |
| PCP | Priority | Typical use |
|---|---|---|
| 1 | Background | Lowest priority (bulk) |
| 0 | Best Effort | Default traffic |
| 2 | Excellent Effort | Important data |
| 3 | Critical Apps | Signaling, DB |
| 4 | Video | < 100 ms latency |
| 5 | Voice | < 10 ms latency |
| 6 | Internetwork Control | Routing protocols |
| 7 | Network Control | Highest priority |
About this tool
This VLAN planner helps you design and validate segmented networks: map VLAN IDs to subnets, check ranges and spot overlaps before you commit a switch configuration. It is built for the moment you are carving a flat network into voice, data, management and guest segments.
Plan addressing per VLAN, confirm there is enough host space in each segment, and keep the layout consistent across your access and distribution switches. Calculations stay in your browser.
Frequently asked questions
What is the valid VLAN ID range?+
Standard 802.1Q VLAN IDs run from 1 to 4094. IDs 0 and 4095 are reserved, and many switches reserve a range (often 1002–1005) for legacy purposes.
Should each VLAN be its own subnet?+
Yes, as a rule each VLAN maps to one IP subnet. Traffic between VLANs is then routed (and can be filtered) at a layer-3 switch or firewall.
How do I size a VLAN subnet?+
Pick a prefix that comfortably fits current hosts plus growth. A /24 (254 hosts) is common for an access VLAN; smaller /26 or /27 blocks suit point-to-point or management segments.