VIP Port Adapter Functions
Serial Distance Limitations
Serial signals can travel a limited distance at any given bit rate; generally, the slower the baud rate, the greater the distance. All serial signals are subject to distance limits beyond which a signal degrades significantly or is completely lost. Table 8 lists the IEEE-recommended maximum speeds and distances for each 4T port adapter serial interface type. The recommended maximum rate for V.35 is 2.048 Mbps.
Table 8 | IEEE Standard EIA/TIA-449 Transmission Speed Versus Distance |
| | | |
| | EIA/TIA-232 | EIA/TIA-449, X.21, V.35, EIA-530 |
| | Distances | | Distances | |
| | | | | |
Rate (bps) | | Feet | Meters | Feet | Meters |
| | | | | |
2400 | | 200 | 60 | 4,100 | 1,250 |
| | | | | |
4800 | | 100 | 30 | 2,050 | 625 |
| | | | | |
9600 | | 50 | 15 | 1,025 | 312 |
| | | | | |
19200 | | 25 | 7.6 | 513 | 156 |
| | | | | |
38400 | | 12 | 3.7 | 256 | 78 |
| | | | | |
56000 | | 8.6 | 2.6 | 102 | 31 |
| | | | |
1544000 (T1) | – | – | 50 | 15 |
| | | | | |
Balanced drivers allow EIA/TIA-449 signals to travel greater distances than EIA/TIA-232. The recommended distance limits for EIA/TIA-449 shown in Table 8 are also valid for V.35, X.21, and EIA-530. EIA/TIA-449 and EIA-530 support 2.048-Mbps rates, and V.35 supports 2.048-Mbps rates without any problems; we do not recommend exceeding published specifications for transmission speed versus distance. Do so at your own risk.
4T Serial Connection Equipment
The 4T port adapter supports synchronous serial connections at speeds of up to 2 Mbps per interface; the speed depends on the type of electrical interface used. Use EIA/TIA-232 for speeds of 64 kilobits per second (kbps) and below, and use X.21, EIA/TIA-449, V.35, or EIA-530 for higher speeds.
EIA/TIA-232 Connections
The router (VIP) end of all EIA/TIA-232 adapter cables is a high-density 60-pin plug. The opposite (network) end of the adapter cable is a standard 25-pin D-shell connector (known as a DB-25) that is commonly used for EIA/TIA-232 connections. Figure 23 shows the connectors at the network end of the adapter cable. The system console and auxiliary ports on the RP in the Cisco 7000 series (or the RSP in the Cisco 7500 series) also use EIA/TIA-232 connections; however, the 4T port adapter interfaces support synchronous serial connections, and the console and auxiliary ports only support asynchronous connections. Use caution when connecting EIA/TIA-232 cables to the 4T receptacles.
48VIP-4R/4T Installation and Configuration
