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 $
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GeoIP
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Good Wi-Fi signal but slow throughput: what to check
Diagnose low throughput despite strong RSSI by checking airtime, retries, channel width, interference, client capability and backhaul.
01
RSSI is only one part of capacity
A client at -50 dBm can still be slow if airtime is saturated, retries are high, the AP is sharing a wide channel badly or the client negotiates a conservative PHY mode. Strong signal answers “can I hear the AP?”; it does not answer “how efficiently can we exchange frames?”.
02
Look at retries, airtime and channel utilization
High retry rates point to collisions, interference, hidden nodes or poor modulation stability. High channel utilization with low user throughput usually means the medium is busy rather than the backhaul being too slow. Compare these counters during the actual busy period.
03
Validate client capability and negotiated width
A modern AP cannot force an old or power-saving client to use more spatial streams, higher modulation or wider channels. Check the client radio, band, channel width, MCS/NSS and driver behavior before blaming the access point.
04
Do not forget wired backhaul and upstream shaping
A perfect RF link can still terminate on a 100 Mbps Ethernet port, a congested mesh backhaul, a rate-limited VLAN or an overloaded gateway. Test local LAN throughput as well as Internet throughput to locate the bottleneck.
05
Separate PHY rate from application throughput
A negotiated PHY rate includes coding, contention and protocol overhead; application throughput will always be lower. Compare like with like and avoid treating the advertised link rate as a speed-test target.
06
Check hidden-node and adjacent-channel behavior
Two clients that cannot hear each other may repeatedly collide at the AP. Adjacent-channel interference is different from co-channel contention and can be especially damaging when channel plans overlap partially.
07
Test one client close to one AP before tuning the whole network
A controlled single-client baseline removes roaming, distance and neighboring-cell variables. If that baseline is poor, fix the AP/backhaul first; if it is good, expand the test outward.
EX
Worked example
- Place one capable client near the AP and measure LAN throughput.
- Record RSSI, negotiated PHY/MCS, channel utilization and retries at the same time.
- Repeat under load and compare latency to the idle baseline.
- Move the same client to the problem area and identify which metric changes first.
✓
Operational checklist
- Check channel utilization and retry rate.
- Confirm client band, width, MCS and spatial streams.
- Verify Ethernet or mesh backhaul speed.
- Compare idle and loaded latency.
- Retest after each single change.
Tools to apply it
Standards and references
🕐 History