Network Time Protocol is designed to be incredibly efficient. The protocol periodically interchanges very small packets of timing information between client and server. Additionally, the protocol is UDP based, which is a low overhead protocol. Therefore, a single server can synchronize very large numbers of clients.
Clients do not poll at fixed intervals, they use adaptive polling. Polling starts at once every 64 seconds and increases up to 1024 seconds when time becomes stable. So, as systems synchronize, traffic naturally decreases.
NTP can also implement a hierarchical time distribution, preventing top level servers from getting overloaded.
In short, NTP scales well because it is stateless, UDP-based, low-bandwidth, hierarchical, and utilizes adaptive polling frequency.
To summarize, NTP has:
- Very low CPU and memory usage.
- A NTP message is only 48 bytes (without extensions).
- Clients use adaptive polling.
- NTP can use a stratum hierarchy instead of everyone querying the same server.
The primary factors affecting how many clients a server can support:
- Server hardware – Processing power and speed.
- Network Capacity – Gigabit Ethernet.
- NTP Configuration – For instance, authentication will slow server throughput.
TimeTools TA-Series NTP Servers
TimeTools TA610 has been tested to process 50,000 NTP requests per second. At a client polling rate of one poll every 64 seconds, the TA610 could synchronize 50,000 x 64 = 3,200,000 clients. At a client polling rate of one poll every 1024 seconds, the TA610 could synchronize 50,000 x 1024 = 51,200,000 clients.
TA610 and TA310 Models:
Processor: Quad core, 64 bit RISC processor at 800 MHz.
Maximum NTP Polling Frequency: 50,000 NTP Requests Per Second (3 million polls per minute).
Maximum Number Of Clients Synchronizing At One NTP Request Every 64 Seconds: 3.2 million
Maximum Number Of Clients Synchronizing At One NTP Request Every 1024 Seconds: : 51.2 million
TA210 Models:
Processor: 64 bit RISC processor at 800 MHz
Maximum NTP Polling Frequency: 20,000 NTP Requests Per Second (1.2 million polls per minute).
Maximum Number Of Clients Synchronizing At One NTP Request Every 64 Seconds: 1.3 million
Maximum Number Of Clients Synchronizing At One NTP Request Every 1024 Seconds: : 20.5 million
TA110 Models:
Processor: 64 bit RISC processor
10,000 NTP Requests Per Second (600K/minute)
Maximum NTP Polling Frequency: 10,000 NTP Requests Per Second (600,000 polls per minute).
Maximum Number Of Clients Synchronizing At One NTP Request Every 64 Seconds: 640,000
Maximum Number Of Clients Synchronizing At One NTP Request Every 1024 Seconds: : 10.2 million