What is Network Latency in Ethernet Switches?

Network latency, a critical aspect of modern networking, has a profound effect on the efficiency of data transmission. Ethernet latency is a term that frequently comes up， but do you have an in-depth understanding of it? This article discusses what network latency is, what causes network delay, how to measure it, and how to reduce it with Ethernet switches. Read on to learn more.

What is Network Latency?

The Latency Meaning in Networking

The term "network latency" refers to the delay in the transmission of data over a network. Ethernet switch latency refers to the specific amount of time it takes for an Ethernet packet to travel through a network switch. A network with a long delay is called a high-latency network, while a network with a short delay is called a low-latency network.

Ethernet switch latency can be conceptualized from two perspectives - one-way latency and round-trip latency. The latter is typically used as the primary metric and includes the total time it takes for an Ethernet packet to travel from source to destination. Today, round-trip delay is an important metric because the device uses the TCP/IP network protocol to send the specific data to its destination and waits for an acknowledgment to come back before sending another. Therefore, this method has a significant impact on the performance of the network. 

The Significance of Network Delay

As an increasing number of companies undergo digital transformation, they are employing cloud-based applications and services to execute essential business functions. Operational activities also rely on data collected from smart devices connected to the Internet, collectively referred to as the Internet of Things (IoT). Delays in latency can lead to inefficiencies, particularly in real-time operations reliant on sensor data. Moreover, high latency diminishes the returns on investments made to augment network capacity, impacting the user experience and customer satisfaction, even if enterprises have implemented costly network infrastructures.

What Causes  Latency in Network?

The previous sections covered the concept of network latency. This section explores the causes of latency. Many factors contribute to the length of network latency. Here are a few potential factors that can contribute to it.

Impact of Transmission Medium

Since data is transmitted through transmission media or links, the impact of transmission media or links on latency is significant. For instance, the latency in optical fiber networks is lower compared to wireless networks. Similarly, every time a network switches from one type of medium to another, the total transmission time increases by a few milliseconds.

Header Analysis 

Latency can arise in Ethernet switches as they occasionally require additional time to analyze packet header details and incorporate essential data. This can result in extended traversal time for packets passing through the switch. 

Storage-Related Packet Delays

Storage delays can occur when packets experience delays in storage or disk access at intermediary devices like switches and bridges.

Security Process Latency

Network delay can be influenced by anti-virus and security processes, which require time to complete message recombination and disassembly before transmission.

Software Bugs

Delays can originate from software bugs on the user's side, contributing to latency in the network.

Measuring Latency Network in Ethernet Switches

As evident from the previous chapter, switch latency constitutes a vital element impacting network latency. Hence, the question arises: How to measure it?

IEEE specification RFC2544

The IEEE RFC2544 specification provides a widely accepted approach for evaluating the latency of store-and-forward devices. RFC2544 requires that the delay test be repeated at least 20 times and that the result be the average of all the test results.

Netperf 

Netperf is a network performance measurement tool for TCP or UDP-based transport. The Netperf test results reflect how fast one system can send data to another system and how fast the other system can receive data.

Ping Pong

Ping Pong represents an approach used to gauge latency within a high-performance computing cluster. This method assesses the round-trip duration of remote procedure calls (RPCs) transmitted via the message-passing interface (MPI).

How to Reduce Network Latency with Ethernet Switches?

Various methodologies are employed to minimize network delay using Ethernet switches. These approaches include:

Increasing Network Capacity

One of the most straightforward and effective approaches to mitigate latency and collisions involves equipping your Ethernet switch with the required capacity.   It's important to verify whether the switch offers the capability to expand network capacity.   Ethernet switches that ensure zero packet loss play a pivotal role in enhancing network performance. The Link Aggregation Control Protocol, or LACP for short, is a standard feature that enhances network performance through port trunking.

Using VLANs for Network Segmentation

Given that conventional flat networks often lead to link overload, Ethernet switches equipped with VLAN capabilities can efficiently route traffic to its intended destinations.  A range of Layer 2 and Layer 3 VLAN Ethernet switches are available for traffic segmentation based on factors like port, dynamic VLAN assignment, protocol, MAC address, and more.

Implementing Cut-Through Technology

This method pertains to packet-switching systems and seeks to minimize network latencies.  Cut-through switching decreases network latency by allowing the switch to initiate packet forwarding even before the complete packet is received, as soon as the destination address is processed.  However, it's important to note that this technology functions optimally when applied to ports operating at the same speed.

Reduce Latency with RDMA

RDMA, or Remote Direct Memory Access, is a cutting-edge networking technology that revolutionizes data transfer efficiency. Unlike traditional methods that involve the CPU, RDMA enables direct data exchange between computer memories within a network. This circumvents the CPU and reduces latency, resulting in accelerated data communication for tasks like real-time simulations, data analytics, and high-performance computing. QSFPTEK's S5600 and S7600 series switches support RDMA to provide high throughput and ultra-low latency.

Conclusion

In conclusion, network latency is vital for efficient data transmission in Ethernet switches. The purpose of this article is to clarify the concept of Ethernet latency in Ethernet switches and provide insight into strategies for reducing it. While it may not be possible to completely eliminate network latency, the goal is to minimize it as much as possible. Understanding network latency's implications and applying mitigation strategies are essential in today's network-dependent landscape.