Allegro Network Multimeter – Simultaneous historical and real-time data traffic analysis

Allegro Packets Network Multimeter is the only device on the market capable of simultaneously analysing historical traffic and real-time data. The Allegro Network Multimeter is a powerful real-time network multimeter for detecting network problems. It measures many performance parameters from Layer 2 to Layer 7 and is used for troubleshooting and network analysis.

All information recorded by the device is available in real-time, including traffic history graphs (per MAC address, IP address, protocol, per connection). In addition, the graphics can be clicked to zoom into a specific time window and display the results only for this time window. The Allegro Network Multimeter uses two different databases to display and process the recorded information:

  • the in-memory database and
  • the packet ring buffer on the hard disk or SSD.

In-Memory Database

The Allegro Network Multimeter uses an in-memory database to store the metadata of the processed packets. This means that all recorded measurement data is available without time-consuming disk access and can be called up for instant searches.

The Allegro Multimeter can operate without an internal or external hard disk and only use in-memory for the metadata, i.e. no data is written to the hard disk.

The in-memory database capacity varies between 2 GB and 1.5 TB depending on the model. As an approximation, the history of about 150,000 connections and their aggregations can be stored per gigabyte in-memory database.

The Allegro Network Multimeter adapts its memory configuration to the quantity of traffic. It always stores all data. If the memory is full, the longest inactive connections and IP addresses are deleted. This means that in smaller networks the device stores historical data for a longer period, while in larger networks the device stores more IP addresses and associated information, but only for a shorter period of time.

The Allegro system’s memory fills up automatically over time (except for a memory reserve) to provide measurement data for as long as possible. Afterwards, old data is automatically deleted to ensure optimal system memory.

Ring Buffer Database

If a packet ring buffer is used, the packets are stored on a connected storage medium. The following systems can be used for this purpose:

  • Internal hard disks or SSDs (Allegro 500 and higher),
  • External hard disks via USB3 (all Allegro Multimeters),
  • iSCSI systems via the management port (all Allegro Multimeters).

The ring buffer makes it possible to create a fixed size packet buffer on which all recorded packets are stored – on one or more external storage devices. When the buffer is full, the oldest packets in the buffer are replaced by new packets.

The ring buffer can also be created over several hard disks. Up to 64 hard disks with a ring buffer of several petabytes are supported. Additionally, a data redundancy with 0 up to 3-fold redundancy is supported.

To prevent misuse, the storage device can be formatted with AES256 encryption (Caution: subsequent access to the disk without a password is not possible).

Whitepaper: In-Memory-DB and Packet Ring Buffer

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