Brooke Jameson
Product Marketing Manager
What is a Network Packet?
A network packet is a multi-byte unit of data transmitted at one time by a host, such as a server, on a network. The actual packet consists of the user data, called the payload, and control information that the network uses to deliver the payload. The term packet is often used interchangeably with frame, although some people distinguish packets as messages at the network layer and above, while frames are defined as messages that include the data link and sometimes even the physical layers.
Packets are small segments of a full message. All data sent over computer networks, meaning 2 or more computers connected to one another, is broken up into packets and then reconstructed by the destination device. Breaking up larger messages into smaller packets helps keep the wires clear for other devices to send information, ensuring the network runs more efficiently. If computers sent messages in their full, undivided state, each device would have to wait its turn to send its messages to other devices.
Network packets can be monitored for a variety of use cases, including network performance management and network security. The versatility and detail of packet data allows for unmatched visibility into your network, meaning that nothing can hide from you, whether it is a performance issue, or a bad actor trying to gain or expand access.
A network packet is comprised of three main parts:
- Packet Header: The header is the initial information of the packet. This is the first part of the packet the receiving device sees. There are 8 components to an IPv6 packet header:
- Version: 4-bit identifier of the Internet Protocol version.
- Traffic Class: Indicates the priority of the packet.
- Flow Label: Indicates that the packet belongs to a specific series of packets.
- Payload Length: Specifies the length of everything in the packet following the header.
- Next Header: Specifies what type of payload the packet contains.
- Hop Limit: Ensures the packet doesn’t fall into an infinite loop. Each time it passes a router, the Hop Limit decreases by one.
- Source Address: Indicates the address of the device sending the packet.
- Destination Address: Indicates the address of the destination device of the packet.
- Payload: The payload is the actual data that is being transmitted to the destination. To ensure the packet is the proper size, the payload may be padded with blank data.
- Trailer: At times, some network protocols will attach a trailer or end part to a packet. For example, Ethernet frames contain trailers, but IP packets do not. This is often done to denote the end of a network packet or perform error correction.
What is packet loss?
Packet loss happens as a result of a single or multiple packets of data traversing a computer network, but failing to arrive at their intended destination. Such a failure can be caused by errors in the transmission of the data over a wireless or wired network. It can also be the result of network congestion. Packet loss is defined as the percentage of packets lost compared to the number of packets sent.
Transmission Control Protocol (TCP) is an important tool for detecting and remedying packet loss. When network packet loss is detected by the TCP, retransmission of the packets is attempted to ensure messages are completed. In some cases, packet loss is intentionally introduced through the TCP connection in order to reduce throughput and alleviate network congestion.
Packet loss can adversely impact a user's quality-of-experience (QoE), particularly in real-time applications, such as online gaming and streaming media.
What is packet switching?
Packet switching involves taking data and grouping it into packets, which are then transmitted over a telecommunications network. Packet switching is the principal way data communications are conducted across computer networks around the world. The packets themselves are composed of a header and a payload. The data contained in the header is utilized by hardware at the network level, directing the packet to its designated destination. Once the packet arrives at its destination, the payload is extracted, where it is processed by an operating system, higher layer protocols, or application software.
The Internet utilizes packet switching. In this type of network, network equipment is allowed to process packets independently from one another, allowing network packets to take different routes to their destination devices to ensure they all reach that destination efficiently. However, some protocols require the packets to arrive in the correct order in order to be processed properly, regardless of the path they took to get there.
What is a Packet Broker?
A packet broker is a hardware or software appliance that directs network traffic from multiple SPAN ports and manipulates the traffic to allow more efficient use of network tools and monitoring devices on the network.Packet brokers are tasked with gathering traffic from numerous network links, then filtering and redirecting the individual packets to the optimal network monitoring tool. By improving the delivery of data across the network, the effectiveness of network monitoring and security tools is attained.
What is a packet analyzer, protocol analyzer or network analyzer?
A packet analyzer is a software program or computer hardware (packet capture appliance) that is used to catch and then log traffic traversing a computer network or part of that network. A packet analyzer may also be referred to as a network analyzer, packet sniffer, or protocol analyzer. (The terms network analyzer and protocol analyzer can also have other meanings.)
Packet capture occurs when the analyzer intercepts each packet as the data streams flow throughout the network. In some cases, the analyzer is tasked with decoding raw data found in the packet in order to reveal the values of certain fields found in the packet. The contents of the packet are analyzed per the applicable specifications.
When a packet analyzer is employed to capture traffic on a wireless network, it is referred to as a wireless analyzer.
How NETSCOUT Utilizes Network Packets
The packet is the foundation of NETSCOUT’s products and solutions. In leveraging the power of the packet, NETSCOUT provides unmatched visibility for security applications with Omnis Network Security and for network and application performance applications with nGenius Enterprise Performance Management. Learn more about how packet-based cybersecurity and performance management solutions are the ideal approach for the most complex networks.