CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

MISC Physical Layer Notes
- The maximum point-to-point transmitting distance for a full-duplex mode 100BaseTX/FX
multimode fiber converter is 2KM; under half-duplex mode, this is limited to 412m.
- The maximum point-to-point transmitting distance for a full-duplex mode 100BaseTX/FX
single-mode fiber converter is 120KM. It is not recommended for a 100BaseTX/FX single-mode
fiber converter to run under half-duplex mode with single-mode fiber.
- To fully utilize the advantage of long-distance transmission with fiber optics, the 100BaseTX/FX
converters should be deployed together with switches instead of hubs, as switches support fullduplex
mode, which allows point-to-point connection up to 2KM for multimode fiber and up to
120KM for single-mode fiber.
- 1000BaseSX Gigabit ports on 10/100 and Gigabit switches only support point-to-point
connections of up to 280m. Gigabit multimode-SX-to-single-mode-LX converters have the
potential to extend the distance to 10KM (the maximum point-to-point transmitting distance is
10KM + 280m = 10280m).
- Below describes the differences between stacking and cascading:
Stacking Connecting multiple switches or hubs together with an SCSI cable. The cable
plugs into the rear port of each switch or hub. The physical switches form a single
logical switch.
Cascading Connecting multiple switches or hubs together with UTP cables. The cables plugs
into the front port of each switch or hub.
Stacking is the better solution when the devices are near to each other; while cascading is more
suitable for linking devices that are further apart or differing makes (vendor, model, etc).
- Note: The backplane speed of a stack is limited to 32Gbps. For comparison, some larger modular
switches can support 720Gbps on their backplanes.
- 2 pairs of wires (1 pair for transmission, another pair for collision detection and reception) in
100BaseTX UTP 8-pin connector are used for full-duplex transmission:
Pin Number Signal
1 TX+
2 TX-
3 RX+
4 -
5 -
6 RX-
7 -
8 -
- DOCSIS – Data over Cable Service Interface Specification.
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