198.18.0.0/15 — the lab-only benchmarking range
198.18.0.0/15 — 131,072 addresses spanning 198.18.0.0 to 198.19.255.255 — exists for one job: benchmarking network devices in the lab. RFC 2544, the standard methodology for measuring throughput, latency and loss, reserved it in 1999 so test traffic gets addresses that cannot possibly collide with any production network.
RFC 6815 later reaffirmed the reservation and added the obvious rule: since benchmark rigs blast devices at line rate with realistic route tables, the range must stay off the public Internet forever.
| Range start | 198.18.0.0 |
| Range end | 198.19.255.255 |
| Subnet mask | 255.254.0.0 |
| Wildcard mask | 0.1.255.255 |
| Total addresses | 131,072 |
Reserved for benchmarking (RFC 2544/6815): nobody subnets it for hosts, so treat these as the block's boundaries, not a network plan.
Why benchmarks needed their own space
An RFC 2544 test bench simulates real Internet conditions: full route tables, mixed frame sizes, line-rate streams. If the tester used 10.x or 192.168.x, its traffic could clash with the lab's own management network; if it used made-up public addresses, it might collide with real routes on the device under test. A globally reserved, never-routed /15 removes both problems at once.
Where you'll actually see it
Spirent, Keysight/Ixia and TRex all default to 198.18.x for their test topologies, and vendor datasheets quote RFC 2544 numbers measured on it. Outside the lab you will meet the range mostly in firewall rulebases — it sits on bogon lists next to the documentation and reserved blocks, because a 198.18.x packet on a production link is always a mistake.
CIDR Calculator
Run the math on 198.18.0.0/15 — or any other block
Frequently asked questions
What is 198.18.0.0/15 used for?
Benchmarking network interconnect devices, per RFC 2544 and RFC 6815. Test equipment uses it to generate realistic traffic with zero chance of colliding with production addressing.
Is 198.18.0.0/15 private like 192.168.x?
Similar in that it must never be routed publicly, but it is not for general private use — it is reserved specifically for device benchmarking, and bogon filters treat it accordingly.
How many addresses are in 198.18.0.0/15?
131,072 (2^17): two contiguous /16 blocks, 198.18.0.0 through 198.19.255.255.
Why does my traffic generator use 198.18 addresses?
Because RFC 2544 reserved that block for exactly this purpose — the tester is following the standard so its streams cannot be confused with, or filtered as, real traffic.