Layer 2 Network

13th January 2022 | Cybrary

Layer 2 Networks refers to the second layer of the Open Systems Interconnection (OSI) Model, which is the data link layer. Layer 2 Network is the link layer (second-lowest layer) in the TCP/IP network model, just above the physical layer. Layer 2 provides two important functions in the OSI model. First, it allows upper layers of the OSI model to access media (data) via framing. Framed packets contain Media Access Control (MAC) addresses for direct communications to local device’s Network Interface Card (NIC). The second critical function of Layer 2 is to control how data is placed and received from the media, (1) Media Access Control (MAC), and Error Detection. In Wireless networks, Layer 2 can also help with Flow Control (something handled at layer 4 in ethernet networks). Error detection is important in TCP communication because this protocol is lossless meaning it must have every packet reassembled for successful communications.

Layer 2 is where data packets are encoded and decoded into bits. Layer 2 is used to transfer data between adjacent network nodes on the same local area network.

Layer 2 provides the procedural and functional means for data transfer between network nodes and provides the means to detect and correct errors that may occur at the physical layer (Layer 1). Layer 2 provides many services, including the following:

Encapsulation of data packets into frames
Frame synchronization
Error and flow control via the LLC sublayer
Physical or MAC addressing
Packet or LAN switching
Data packet scheduling
Virtual LANs

Pneumonics help cybersecurity professionals remember the OSI Model.

Please = Physical = Layer 1

Do = Data = Layer 2

Not = Network = Layer 3

Tell = Transport = Layer 4

Secret = Session = Layer 5

Password = Presentation = Layer 6

Anyone = Application = Layer 7

What does this mean for an SMB?

Layer-2 is all about data deliver and service reliability (error correction of hardware issues). Inter-network routing and global addressing are higher-layer functions, allowing data-link protocols to focus on local delivery, addressing, and media arbitration. Layer 2 Networks can be used for SMBs to segment networks into VLANs (virtual local area networks) and even PVLANs (Private VLANs). Segmenting your network can be very beneficial to your business’ security. Network segmentation helps limit the spread of malware, viruses, or even hackers because the internal trusted network is no longer flat and open. This helps you accomplish a zero-trust network framework. For example, if a hacker gained access to your network through someone on your Finance team, the hacker would not be able to move laterally to another part of the network without compromising a host on that network and even then, only if the hacker can see or communicate with a host in the other isolated network because the network is segmented.

Firewalls are commonly deployed in SMB’s with Wireless Network capabilities that allow you to physically and logically segregate guest Wi-Fi networks from trusted Wi-Fi networks. Make sure you tie your Trusted Wi-Fi network into your Active Directory user accounts (using Radius) instead of a static password. This eliminates a common risk of terminated employees sitting on your trusted Wi-Fi network in the Parking lot to siphon off sensitive data or cause additional harm to your company.

Additional Cybersecurity Recommendations

Additionally, these recommendations below will help you and your business stay secure with the various threats you may face on a day-to-day basis. All of the suggestions listed below can be gained by hiring CyberHoot’s vCISO Program development services.

Govern employees with policies and procedures. You need a password policy, an acceptable use policy, an information handling policy, and a written information security program (WISP) at a minimum.
Train employees on how to spot and avoid phishing attacks. Adopt a Learning Management system like CyberHoot to teach employees the skills they need to be more confident, productive, and secure.
Test employees with Phishing attacks to practice. CyberHoot’s Phish testing allows businesses to test employees with believable phishing attacks and put those that fail into remedial phish training.
Deploy critical cybersecurity technology including two-factor authentication on all critical accounts. Enable email SPAM filtering, validate backups, deploy DNS protection, antivirus, and anti-malware on all your endpoints.
In the modern Work-from-Home era, make sure you’re managing personal devices connecting to your network by validating their security (patching, antivirus, DNS protections, etc) or prohibiting their use entirely.
If you haven’t had a risk assessment by a 3rd party in the last 2 years, you should have one now. Establishing a risk management framework in your organization is critical to addressing your most egregious risks with your finite time and money.
Buy Cyber-Insurance to protect you in a catastrophic failure situation. Cyber-Insurance is no different than Car, Fire, Flood, or Life insurance. It’s there when you need it most.

All of these recommendations are built into CyberHoot the product or CyberHoot’s vCISO Services. With CyberHoot you can govern, train, assess, and test your employees. Visit CyberHoot.com and sign up for our services today. At the very least continue to learn by enrolling in our monthly Cybersecurity newsletters to stay on top of current cybersecurity updates.

Watch this video for detailed OSI model information

Sources:

Techopedia

Juniper

Additional Reading:

What is the Most Scalable Protocol in Layer 2?

Network Segmentation

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