 Parameters ITU-T Rec. Q.706 (Ref. 10) breaks down SS No. 7 performance into three parame- ter groups: 1. Message delay 2. Signaling traffic load 3. Error rate 3 OPC and DPC are discussed in Section 14.7. CCITT SIGNALING SYSTEM NO. 7 Consider the following parameters and values: Availability The unavailability of a signaling route set should not exceed 10 min per year. Undetected Errors Not more than 1 in 1010 of all signal unit errors will go undetected in the message transfer part. Lost Messages Not more than 1 in 107 messages will be lost due to failure of the message transfer part. Messages Out of Sequence Not more than 1 in 10 10 messages will be delivered sequence to the user part due to failure in the message transfer part. This includes message duplication. 14.9.2 Traffic Characteristics Labeling Potential There are 16,384 identifiable signaling points. Loading Potential Loading potential is restricted by the following four factors: 1. Queuing delay 2. Security requirements (redundancy with changeover) 3. Capacity of sequence numbering (127 unacknowledged signal units) 4. Signaling channels using bit rates under 64 kbps 14.9.3 Transmission Parameters The message transfer part operates satisfactorily with the following error performance: Long-term error rate on the signaling data links of less than 1 X 10- Medium-term error rate of less than 1 X 10-4 14.9.4 Signaling Link Delays over Terrestrial and Satellite Links Data channel propagation time depends on data rate (i.e., this reduces transmission time, thus transmitting a data message at 64 kbps requires half the time compared to 32 kbps), the distance between nodes, repeater spacing and the delays in the repeaters, and in switches. Data rate (in bps) and repeater delays depend on the type of medium4 used Table 14.2 Calculated Terrestrial Transmission Delays for Various Call Distances Delay Terrestrial (ms) Arc Length (km) Fiber Radio 1,000 2,000 5,000 10,000 15,000 17,737 20,000 100.0 25,000 120.0 125.0 4Remember that the velocity of propagation is a fun