Ethernet Throughput Calculator: Network Speed & Bandwidth

What is the difference between bandwidth and throughput?

Bandwidth is the theoretical maximum data transfer rate of a network connection, while throughput is the actual amount of data successfully transferred over time. Throughput is always lower than bandwidth due to various overheads and real-world conditions.

What are jumbo frames and when should I use them?

Jumbo frames are Ethernet frames larger than the standard 1500 bytes MTU, typically 9000 bytes. They improve efficiency by reducing overhead for large data transfers, but all network devices must support them. They're commonly used in storage networks and data centers.

Why is my actual network speed lower than the rated speed?

Several factors contribute to lower actual speeds:

• Protocol overhead from TCP/IP or UDP/IP headers
• Inter-frame gaps and preambles
• Network congestion and packet loss
• Processing delays at network devices
• Half-duplex operations and collisions

What is TCP/IP overhead and how does it affect throughput?

TCP/IP overhead consists of both TCP header (20 bytes) and IP header (20 bytes), totaling 40 bytes per packet. This overhead is necessary for reliable data delivery but reduces the amount of space available for actual data in each frame. Additionally, TCP's acknowledgment mechanism and flow control can further impact throughput, especially on high-latency networks.

When should I use UDP instead of TCP?

Consider using UDP when:

• Real-time performance is more important than guaranteed delivery (e.g., video streaming, gaming)
• The application can handle occasional packet loss
• You need maximum throughput with minimal protocol overhead
• Network conditions are generally good with low packet loss

What is the impact of network utilization on throughput?

Network utilization affects throughput in several ways:

• Higher utilization increases the likelihood of packet collisions in half-duplex networks
• Network congestion can lead to increased latency and packet loss
• Quality of Service (QoS) mechanisms may throttle certain traffic types
• Buffer overflows in network devices can cause packet drops

How do different Ethernet standards affect frame timing?

Each Ethernet standard has specific timing requirements:

• Inter-frame gap (IFG): 96 bit times (12 bytes)
• Preamble and Start Frame Delimiter (SFD): 8 bytes
• Minimum frame size: 64 bytes (to ensure collision detection)
• Maximum standard frame size: 1500 bytes (MTU)

What is the relationship between frame size and network efficiency?

Frame size impacts network efficiency in several ways:

• Larger frames have better efficiency due to lower overhead ratio
• Smaller frames provide lower latency for time-sensitive applications
• Maximum transmission unit (MTU) limits frame size on the network path
• Frame fragmentation can occur if packets exceed the MTU

How can I optimize network performance for different applications?

Different applications require different optimization strategies:

What role does duplex mode play in network throughput?

Duplex mode significantly affects network performance:

• Full-duplex allows simultaneous bidirectional transmission
• Half-duplex requires taking turns to transmit
• Duplex mismatches can cause severe performance issues
• Modern networks typically operate in full-duplex mode

How do errors and collisions affect throughput?

Network errors and collisions can impact throughput through:

• Packet retransmissions consuming bandwidth
• Exponential backoff periods after collisions
• Error detection and correction overhead
• Reduced window sizes in TCP connections

What is the significance of Inter-frame Gap (IFG)?

The Inter-frame Gap (IFG) or Inter-packet Gap (IPG) serves several important purposes:

• Allows network equipment to process each frame
• Prevents frame collisions in half-duplex networks
• Provides synchronization time for network interfaces
• Required by Ethernet standards (minimum 96 bit times)

How does network latency affect throughput calculations?

Latency affects throughput in several ways:

• Higher latency increases TCP round-trip time (RTT)
• Affects TCP window scaling and flow control
• Can impact application-level protocols
• May require larger TCP windows for optimal performance