user@netcalc ~/calc $
ipv4_calculator
Calculate network, broadcast, mask, hosts, class and binary for any IPv4 address
ip:
mask:
✓ stdout — ipv4_calculator
Enter runs the calculation · Shift+Enter inserts a new line
user@netcalc ~/calc $
ipv6_calculator
Calculate network info for IPv6 addresses in CIDR notation
ipv6:
pfx:
✓ stdout — ipv6_calculator
user@netcalc ~/calc $
vlsm_calculator
Variable Length Subnet Mask — assigns optimal blocks for each network segment
net:
pfx:
// Subnets required
name:
hosts:
name:
hosts:
name:
hosts:
✓ stdout — vlsm_calculator
| # | Name | Hosts Req | Hosts Avail | Prefix | Network | First Host | Last Host | Broadcast | Mask |
|---|
user@netcalc ~/calc $
usable_ip_range
Shows the exact usable host range for a given network
ip:
mask:
✓ stdout — usable_ip_range
user@netcalc ~/calc $
binary_ip_calc
Convert IP addresses to binary and vice versa, with per-octet visualization
dec:
bin:
✓ stdout — binary_ip_calc
user@netcalc ~/network $
cidr_converter
Convert between CIDR, decimal mask and wildcard. Includes full /1–/32 reference table.
in:
✓ stdout — cidr_converter
📋 CIDR Reference Table
| CIDR | Subnet Mask | Wildcard | Hosts | /24 subnets | Block |
|---|
user@netcalc ~/network $
wildcard_mask_calc
Calculate the wildcard (inverse) mask for Cisco ACLs, OSPF and firewall rules
mask:
✓ stdout — wildcard_mask_calc
user@netcalc ~/network $
supernet_calculator
Find the minimum supernet containing all specified networks (route summarization)
nets:
✓ stdout — supernet_calculator
user@netcalc ~/network $
subnet_splitter
Split a network into equal subnets by specifying a new prefix
net:
mask:
new:
✓ stdout — subnet_splitter
| # | Network | First Host | Last Host | Broadcast | Hosts | Mask |
|---|
user@netcalc ~/network $
range_to_cidr
Convert an IP range (start–end) to the minimum set of CIDR blocks
start:
end:
✓ stdout — range_to_cidr
| # | CIDR Block | Network | Broadcast | Hosts |
|---|
user@netcalc ~/network $
ip_to_integer
Convert IPv4/IPv6 addresses to integer and vice versa
ip:
int:
✓ stdout — ip_to_integer
user@netcalc ~/network $
ipv6_normalize
Expand and compress IPv6 addresses — normalize any valid format
ipv6:
✓ stdout — ipv6_normalize
user@netcalc ~/network $
hex_ip_converter
Convert between hexadecimal and IP address — useful for Windows route tables and Cisco logs
ip:
0x:
✓ stdout — hex_ip_converter
user@netcalc ~/network $
vlan_calculator
802.1Q VLAN info: tag encoding, PCP, DEI, VID, range and compatibility
vlan:
pcp:
dei:
✓ stdout — vlan_calculator
user@netcalc ~/dns $
reverse_dns_generator
Generate the PTR in-addr.arpa zone for an IPv4 network
net:
pfx:
dom:
✓ stdout — reverse_dns_generator
user@netcalc ~/dns $
ipv6_ptr_generator
Generate the PTR ip6.arpa record for an IPv6 address
ipv6:
host:
✓ stdout — ipv6_ptr_generator
user@netcalc ~/dns $
ip_geolocation
Locate a public IP or resolve a domain and geolocate its public address
Domains are resolved through DNS first; geolocation is based on the resulting public IP.
geo:
✓ stdout — ip_geolocation
user@netcalc ~/dns $
ip_address_planner
Interactive IP address space planner — click cells to edit, export to CSV
📋 IP Address Plan
| # | Name | Network | Mask/CIDR | Gateway | VLAN | Location | Notes |
|---|
user@netcalc ~/legal $
Privacy
Data stored in your browser
Theme, language, promotion dismissal and calculation history are stored in localStorage on this device.
Calculations
Calculations are sent through this site's same-origin Worker proxy to the private calculation service.
Performance metrics
LCP, CLS and INP may be stored as aggregate performance measurements by tool and language. Calculation inputs and persistent user identifiers are not included.
GeoIP
Only GeoIP lookups are processed by an external provider. The requested IP address is sent for that lookup.
Issue reports via Telegram
A report link opens the public Telegram bot and includes only the current page slug in the bot start parameter. Calculator inputs and report text are not sent by this website. Text you choose to send inside Telegram is handled by Telegram and the bot.
Cookies and advertising
Advertising is controlled by the production configuration. When Google AdSense is enabled, consent is handled through a certified CMP before personalized advertising is used where required.
Delete local data
Use the button below to clear calculation history. To remove every local preference, clear this site's data in your browser settings.
This page provides operational information; it is not a legal-compliance certification.
VLAN trunk troubleshooting: tagged, untagged and native VLAN mistakes
Trace VLAN membership end to end and identify PVID, native VLAN and allowed-list mismatches that create partial or intermittent connectivity.
01
Trace one VLAN from endpoint to endpoint
Start with the access port, then every trunk, bridge and virtual interface the frame crosses. Record whether each hop expects the VLAN tagged or untagged. A single disagreement is enough to strand only one service while others keep working.
02
PVID and native VLAN solve ingress classification, not magic translation
An untagged frame arriving on a port is assigned to a VLAN according to that port’s ingress rules. The same VLAN may leave another port tagged or untagged. Treat ingress classification and egress tagging as separate decisions.
03
Allowed VLAN lists create partial failures
A trunk can carry management and voice correctly while silently dropping a new customer VLAN because the VLAN is missing from an allowed list on one side. Compare both ends and intermediate switches rather than assuming the trunk is healthy because some traffic works.
04
Avoid relying on mismatched native VLAN behavior
Different vendors expose native, PVID, untagged and hybrid concepts with different syntax. Build an explicit tagging matrix for each link and verify it with MAC learning or packet capture instead of translating commands by name alone.
05
Use MAC learning as a layer-2 tracer
A source MAC should appear in the expected VLAN on each switch along the path. If it disappears or moves to a different VLAN at one hop, you have localized the tagging or PVID mismatch.
06
Remember that management traffic can use a different VLAN than customer traffic
Being able to manage both switches proves IP reachability for the management VLAN only. It does not prove that the customer VLAN is present in the trunk allow-list.
07
Document trunks as a matrix
For each link, record allowed VLANs and whether each one exits tagged or untagged. This neutral description translates much better between MikroTik, Cisco, Huawei and smart-switch terminology than vendor-specific labels alone.
EX
Worked example
- Host A is untagged in VLAN 40 on Switch 1.
- The uplink must carry VLAN 40 with the same tagging expectation on both switches.
- Switch 2 maps VLAN 40 to the destination access port as untagged.
- If MAC 40 disappears on the trunk, compare allowed VLANs and PVID/native settings on both ends.
✓
Operational checklist
- Write the VLAN/tagging matrix for every trunk.
- Compare allowed VLAN lists on both ends.
- Verify PVID/native VLAN for untagged ingress.
- Use MAC learning or capture to prove the failing hop.
Tools to apply it
Standards and references
🕐 History