RFATM vs STM: Asynchronous vs Synchronous Transfer Modes Explained
transfer mode
atm
stm
multiplexing
data communication
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This article compares Asynchronous Transfer Mode (ATM) and Synchronous Transfer Mode (STM), highlighting their differences.
ATM (Asynchronous Transfer Mode)
ATM utilizes statistical multiplexing to efficiently transmit data.
- Operation:
- Upper-layer data is divided into packets of 48 bytes each.
- A header is added to each packet, creating an ATM cell.
- Packets are transmitted only when there’s data to send, making it efficient.
- Statistical Multiplexing: ATM uses statistical multiplexing.
- Advantages: It’s better than STM because no bandwidth is wasted when a source is idle.
- Disadvantages: The added header introduces overhead, causing delays as packets traverse the network.
STM (Synchronous Transfer Mode)
STM operates similarly to Time Division Multiplexing (TDM).
- Operation:
- STM assigns dedicated bandwidth to each source.
- Each source gets a periodic turn for transmission.
- No header is added to packets.
- Advantages: The absence of headers means no overhead and fixed delays.
- Disadvantages: It’s unsuitable for bursty traffic sources. Alloted bandwidth is wasted when a source is idle.
Key Differences: ATM vs. STM
| Feature | ATM (Asynchronous Transfer Mode) | STM (Synchronous Transfer Mode) |
|---|---|---|
| Multiplexing | Statistical | Synchronous (TDM-like) |
| Header | Present | Absent |
| Bandwidth Allocation | On-demand | Dedicated |
| Overhead | High | Low |
| Delay | Variable | Fixed |
| Bursty Traffic | Suitable | Unsuitable |
| Idle Source | No Bandwidth Used | Bandwidth Wasted |
