Calculate Diameter signaling transaction capacity for a given link and message rate.
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.
Transactions per second
tps = link_bandwidth_bps / (avg_msg_size_bytes × 8)
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.
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.
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.