Diameter Capacity
Calculate Diameter signaling transaction capacity for a given link and message rate.
About Diameter Capacity
Diameter is the AAA (Authentication, Authorization, Accounting) signaling protocol underpinning 4G/5G core network interfaces (S6a, Gx, Gy, Rx, and others), and its transaction throughput is bounded by link bandwidth divided by average message size, similar in principle to SS7 MSU throughput. Diameter messages vary considerably in size depending on the application and number of AVPs (Attribute-Value Pairs) carried, so average message size should reflect the actual mix of Diameter applications running over the link rather than a single message type. As with SS7, signaling links are typically provisioned with utilization headroom to absorb failover traffic from redundant peers.
Formula
Transactions per second
tps = link_bandwidth_bps / (avg_msg_size_bytes × 8)
Worked example
With the default values below, Diameter Capacity returns Recommended Sustained Throughput of 12,500. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Link Bandwidthminimum 0.1 Mbps
- 100 Mbps
- Average Diameter Message Sizeminimum 1 bytes
- 500 bytes
- Target Link Utilizationaccepts 1–100
- 50
Results
- Recommended Sustained Throughput
- 12,500 TPS
- Theoretical Max Throughput (100% utilization)
- 25,000 TPS
Step by step
- 1Values used
- 2Transactions per second
- 3Recommended Sustained Throughput= 12,500 TPS
- 4Theoretical Max Throughput (100% utilization)= 25,000 TPS
Assumptions and limits
- The result is derived only from the 3 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
Why does Diameter message size vary so much between applications?
Diameter's AVP-based structure means message size depends heavily on which application it belongs to and how many attributes are carried — a simple S6a authentication message may be a few hundred bytes, while a Gx policy/charging message with detailed QoS rules or a Gy credit-control message with usage data can carry many more AVPs and grow well past 1000 bytes.
How does this compare to SS7 MSU throughput calculations?
The underlying math is identical — bandwidth divided by average message size in bits — reflecting that both are message-oriented signaling protocols. The key practical difference is that Diameter runs over IP/SCTP/TCP at much higher link speeds than legacy 64 kbps SS7 links, supporting the vastly higher transaction volumes required by modern mobile data and VoLTE signaling.
What happens if a Diameter link exceeds its recommended TPS capacity?
Excess transactions queue and experience increased latency, and if buffers overflow the Diameter stack may respond with DIAMETER_TOO_BUSY errors or drop requests entirely — for latency-sensitive procedures like authentication or session setup, this directly delays or fails subscriber-facing operations like call setup or data session establishment.