Layer 2 network mapping gives IT and network professionals valuable information about how devices are physically connected.What is Layer 2, and what can you do with it?
What is Layer 2?
Layer 2 refers to the data link layer of the network. Thisis how data moves across the physical links in your network. It's how switches within your network talk to one another. Installing Layer 2 on your infrastructure gives you high-speed connectivity between devices. It can alsoprovide you with improved network performance.
To create a Layer 2 map of your network, network mapping softwarewill look at your devices and the data they provide. Specifically, it will look at theSNMP-Bridge MIBto tell you how your network is constructed based on what it sees.
Nowadays, software that can create Layer 2 outputs or maps is a necessity for many IT professionals because of the details it can giveyou.
Related Content: Finding Your Way: Mapping Your Network to Improve Manageability
What is the Difference Between Layer 2 and Layer 3?
While Layer 2 is the data link layer of your network, Layer 3 usesIP addresses to communicate between network infrastructure. Layer 3 mapping scans for IPs of devices and determines the networks and subnets they're associated with to build out the Layer 3 map.
Layer 2 Network Mapping
When you enable Layer 2, you're able to see much more information on the state of your network. Here's what you can do with Layer 2:
- See what's connected to your switches
- Discover a device's MAC address and what VLAN it's connected to
- Eliminate the need for cable tracing by easily seeing what a port is connected to
- Identify spare ports on your network
- Discover problem machines on your network and shut down the port
- Search your network by MAC address to find a missing machine
- Avoid network shutdowns by identifying switch loopbacks
- Identify switch-to-switch connections and build a backbone Layer 2 map
- Build Layer 2 network maps one switch at a time or of the whole network using auto-discovery
Layer 2 Protocols
There are several Layer 2 protocols used during the engine scan. These include:
- SNMP: Simple Network Management Protocol is used for collecting information from devices and configuring them.
- CDP: Cisco Discovery Protocol is used to share information about directly-connected Cisco equipment
- LLDP: Link Layer Discovery Protocol is used to advertise the identity, capabilities, and neighbors on a wired LAN Ethernet. It gathers the sys name, description, port name, VLAN, etc.
- STP: Spanning Tree Protocol works on the switch of a bridged Ethernet LAN, ensuring you do not create loops when you have a redundant path in your network.
- ARP: Address Resolution Protocol is used to map an IP address to a physical address (MAC) that is recognized on the local device.
- FDB: Forwarding Database is used by Layer 2 devices to store which ports the mac was learned on. When an Ethernet frame arrives at a Layer 2 device, the Layer 2 device will inspect the destination MAC address of the frame and look to its FDB table for information on where to send that specific Ethernet frame.
Optimizing Your Network for Layer 2
Your Layer 2 data will only be as good as your network configuration. If your devices aren’t configured properly, the Layer 2 information you receive won’t be very accurate.
They are still many networks out there that are running older SNMP implementations or don’t even have SNMP turned on. This will directly impact their ability to discover and map Layer 2 connections. So if you want Layer 2 data, it’s important to first and foremost optimize your network by making sure your infrastructure has been configured properly.
When you use Layer 2 with anetwork mapping software,any map containing Layer 2 switches can be updated automatically to show how those devices are interconnected and the ports through which they are connected. These tools typically provideyou with multiple Layer 2 scanning options. You can either do a full scan of your entire infrastructure to include endpoint connects, or throttle the scan to just display your switching backbone.
Layer 2 gives you a detailed account of network activity and device statuses. You'll be able to easily find out how devices were configured and if they're performing up to par in real time.Finding a reliable network monitoring solution that allows you to create Layer 2 maps willhelp you keep your network running smoothly.
FAQs
Layer2 is the network layer used to transfer data between adjacent network nodes in a wide area network or between nodes on the same local area network. A frame is a protocol data unit, the smallest unit of bits on a Layer 2 network.
What is a layer 2 network diagram? ›
Layer 2 network diagrams give them a more accurate depiction of how the devices are wired in the network. Edge-to-edge connectivity doesn't just include routers: it also encompasses switches and all network devices that have a MAC address and a discovery protocol enabled (such as SNMP).
What is the layer 2 of the OSI model? ›
Layer 2 of The OSI Model: Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the physical layer.
What are layer 2 protocols in networking? ›
Layer 2 protocols or network L2 protocols are a list of communication protocols used by Layer 2 devices (such as network interface cards (NIC), switches, multiport bridges, etc.) to transfer data in a wide area network, or between one node to another in a local area network.
Is ARP layer 2 or 3? ›
The Address Resolution Protocol is a layer 2 protocol used to map MAC addresses to IP addresses. All hosts on a network are located by their IP address, but NICs do not have IP addresses, they have MAC addresses. ARP is the protocol used to associate the IP address to a MAC address.
What is the main function of the layer 2? ›
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).
What is OSI layer 2 for dummies? ›
The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer.
What is layer 2 security in networking? ›
In simple terms, Layer 2 security refers to the measures taken to protect the data link layer in network communications. It encompasses protocols like Ethernet, VLANs (Virtual Local Area Networks), MAC address filtering, and more.
What devices are on OSI layer 2? ›
The Seven Layers of the OSI Model
| OSI LAYER | DEVICES | PROTOCOLS |
|---|
| SESSION layer 5 | | NetBIOS |
| TRANSPORT layer 4 | | NetBEUI, TCP, SPX, NWlink |
| NETWORK layer 3 | Routers, layer 3 (or IP) switches. | IP, IPX, NWlink, NetBEUI |
| DATA LINK layer 2 | Bridges and switches, Ethernet incorporates both this layer and the Physical layer. | - |
3 more rowsA layer 2 device is a device that makes a forwarding decision on a physical address. Most commonly, you'll find a bridge or a switch and the address they use is a MAC address. When a frame arrives at the device, it first takes the source address and places it in the MAC address table for 300 seconds (or five minutes).
Layer 2 switches offer limited to no routing capabilities within network segments such as VLANs. Layer 3 switches offer routing between different network segments. Limited scalability. Higher scalability enabled by layer 3 switches' cross network segment routing capabilities.
What is a Layer 2 issue? ›
Switches are typically considered Layer 2 devices. Problems that can occur at this layer include, MAC addressing errors, duplex errors, collisions, CRC frame errors, and spanning-tree problems. Ways to detect if Layer 2 errors are occurring are by using various show commands.
What layer is DNS? ›
DNS is an Application-layer protocol. The Application layer is the top-most layer on the TCP/IP Model. Just like every application layer protocol, DNS uses the User Datagram Protocol (UDP) on the Transport layer of the TCP/IP model to transport data.
What layer is TCP? ›
Transport Layer (Layer 4)
Layer 4 is the Transport layer. The transport layer creates virtual Transfer Control Protocol (TCP) or User Datagram Protocol (UDP) connections between network hosts. This layer sends and receives data (packets) to and from the applications running on its host.
What layer is DHCP? ›
DHCP works on the Application layer of the TCP/IP Protocol. The main task of DHCP is to dynamically assigns IP Addresses to the Clients and allocate information on TCP/IP configuration to Clients.
What is layer 2 simplified? ›
Layer 2: Scaling Layer
Role: built on top of layer 1 to improve scalability and transaction speed. These are protocols or solutions like Lightning Network for Bitcoin or Plasma and Rollups for Ethereum. They handle transactions off the main chain (Layer 1) and periodically update the main chain.
What is the layer 2 approach? ›
Instead, Layer-2 solutions enable faster and more efficient transaction processing by conducting transactions off-chain and settling them on the main chain only when necessary. This approach reduces congestion on the main chain, increases transaction throughput, and improves overall network performance.
What is the point of layer 2? ›
Layer 2 technology is part of what is called the OSI (Open Systems Interconnection) model. It is the layer at which data moves from the physical layer into the cybersphere. It is the launching pad for data.
What is the concept of a layer 2 switch? ›
Layer 2 switches are similar to bridges. They interconnect networks at layer 2, most commonly at the MAC sublayer, and operate as bridges, building tables for the transfer of frames among networks. Historically, layer 2 switches emerged to alleviate the contention problem of shared media LANs.
