Networks these days are complexand include manycluttered interconnections. Trackinga network'sconnections and monitoring eachof itsnodes and links requirestechnologythat'scapable of discovering the various layers of that network.The only way to guarantee successful mapping is with a combination of theright mechanismsand a good understanding of how they work.Site24x7'sLayer 2Mapshelps network professionalsview worthwhile information about the physical interconnectionsexistingintheirnetworks.
Layer 2—defined as thedata link layer—discovers port-to-port connections and linking properties.
Table of contents
- The Layer 2 Maps view
- Discovery mechanisms
- Creating Layer 2 maps
- Understanding the discovered maps
- Editing the layout
- Adding discovered devices for monitoring
The Layer 2 Maps view
Log in toSite24x7, clickNetwork on the left panel, and selectLayer 2 Maps.
Here, you can create and view Layer 2 network maps as well as rediscover, edit, and deletemaps.
Figure 1. The Layer 2 Maps view.
Discovery mechanisms
Site24x7 discovers and maps Layer 2 networks based on the following protocols and discovery mechanisms:
- Address Resolution Protocol (ARP):ARPis used to map an IP address to a physical address or media access control address (MAC address) that is recognized on the local device. ARP is mainly for layer 3 switches and routers.
- Cisco Discovery Protocol (CDP):CDPis used to share information aboutCisco devices that are directly connected. If your device is a Cisco device, we recommendusing CDP for discovery.
- ForwardingDatabase (FDB):TheFDBtable is used byLayer 2 devices to store the MAC addresses that have beendiscovered and the ports thoseMAC addresswerediscovered on. In general, switches are discovered usingtheFDB.
- IProute: IProutes are routes taken fromarouting table.Routing tables containnecessaryinformationforforwarding a packet along the best path toward its destination. Common routers and switches are discovered usinganIProute.
- Link Layer Discovery Protocol (LLDP):LLDPis used toadvertise the identity, capabilities, and neighbors on a wired LAN ethernet.LLDP is used to discover wired LAN ethernets.
Creating Layer 2 maps
- Log in toSite24x7.
- Navigate toNetwork >Layer 2 Maps > Create New.
- In theCreate Map form that opens, enter the following:
- Map Name:Enter a name to identify your map.
- Discover From:Select Devices if you wish to discover and create a network map using a network device that is already being monitored. Select one from the drop-down. If the device is not yet being monitored by Site24x7,chooseIP Addressand, in the box that appears below, enter the IP address of the deviceyou wish to discover and map.
- IP Filters:Enter the start and end IPs of an IP rangeyou want discovered. You should add a minimum of one IP range and can add more by clicking+.
- Credentials to Use:Choose the credentials to use from the drop-down list. You can choose multiple credentials andadd new credentials as well by clicking on+ next to the drop-down list.
- Discovery Mechanisms: Select appropriatediscovery mechanisms from the drop-down list.Selecting FDB or LLDP will automaticallyselect ARP along with it. Always select an additional discovery mechanism while choosing ARP.
- Location Profile:Choose theOn-Premise Poller from which the map has to be discovered(i.e. the On-Premise Poller installed in the same network as the device).
- ClickStart Discovery.
Figure 2. Discovering a Layer 2 map.
If your map is not discovered properly, click here to troubleshoot.
Understanding the discovered Layer 2 maps
- Discovered and monitored devices are displayed as colored tilesforthe following statuses: green forUp, red forDown, yellow forTrouble, blue forConfiguration error, dark grey forDiscovery in progress, lilac forMaintenance, and light grey forSuspended. Unmonitored devices are displayedaswhite tiles.
- By default, the map structure is displayed as Radial Tree structure,butyou canchange it to theNode Linkstructure if you prefer.Once you'vechanged the structure, don't forget to save your view.
- You can pan the map, zoom out, or zoom in and, once you've chosen your preferred position, you cansave your changes to retain this position.
- Hover over a node to view basic configuration details for the device along with the number of interfaces that areUp, Down, or in Trouble.
- Click on a node to view a graph of the network device's real-time performance stats such as response time and packet loss.
- Hover overlinks to viewbasic configuration details, operational states, and admin states of the interface.
- Click on a link to view a graph of the interface's real-time performance stats like traffic, packets, errors, and discards.
- View the status of nodes and links as green, red, or yellow, which denote that they're Up, Down, or inTrouble, respectively.
- Viewlinks between network devices turn red or yellow when the connected interface is Down or in Trouble.
- ClickRediscoverto obtain the latest status and data of the devices and interfaces.
- You can alsoedita map and change IP ranges, credentials, and discovery mechanisms.
- Check theping response ofadevice and viewitstraceroute from the map.
Figure 3. Viewing the Layer 2 map.
Editing the map's layout
ClickEdit Layoutto edit the map's layout and adjust the spacing between the links. You can edit the layout for bothRadialTree andNodeLink structures. Basically, both these structures provide you with the same device interconnection mapping. They only differ in the aesthetic view. The Radial Tree looks like a tree with the seed node at the centre. Whereas, in the Node Link structure, the links are arranged level-wise.
RadialTree structure:
- RingSpacing: The spacing between the nodes.
Node link structure:
- Map Orientation: This caneitherbelandscape or portrait.
- Tree Spacing: The depth of the tree.
- Node Spacing: The spacing between the nodes.
- Sub-tree Spacing: The distance between two sibling nodes.
Adding a discovered device for monitoring
Once your map is discovered,you canadd unmonitored devices for monitoring directly from the map. Selecttheproper credentials,give a proper display name, and start monitoring.
- ClickAdd Allto add all the discovered, unmonitored devices for monitoringat once.
- Hover over an unmonitored device and clickClick to monitor to start monitoring that device.
- You can also click directly on an unmonitored deviceto start monitoring it.
Figure 4. Adding a device for monitoring.
Related articles
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