For example, with VMWare vSphere, the virtual switches can support CDP and LLDP. Each hypervisor adds at least one virtual switch used to bridge the VM networks to the physical networks.ĭepending on the hypervisor, different solutions are used to show the network topology. You can use a hypervisor to help figure out the complex network topology. With dynamic routing protocols (like OSPF or BGP), you can query the IP neighbors to identify routers that are announcing or receiving the routing rules. However, most modern networks use a routing protocol to exchange information. Each router can show the route entries and the closest routers in those entries. With static routing, it’s quite easy to display the configuration. Because of how these tools interact with broadcast boundaries, they are only effective inside a single network. On a single logical network, you can use a broadcast ping, specific IP scanning tools, or ARP cache discovery (among other similar tools) to identify the different nodes in the same network. With this protocol, you can find the paths of a packet and discover the logical networks and routers. One common tool used to identify the different network hops is traceroute (tracert on windows), although some implementations might use UDP packets instead of ICMP packets. In an IP-based network, Internet Control Message Protocol (ICMP) is the standard discovery protocol. Because of the effort involved, this method is usually the last resort. Most switches support one or both protocols.Īnother more complex way is to analyze the MAC address table of each switch, and/or the spanning tree protocol packets, to find where the MAC addresses are connected. These protocols can be used to identify who, or what, is connected to a specific network port by listening to the LLDP or CDP messages, or also to announce that a device is connected to a specific port. Cisco Discovery Protocols (CDP) is a proprietary data link layer protocol developed by Cisco, and it is used and supported by other network vendors.This enables you to automatically discover and advertise the node neighbors. Link Layer Discovery Protocol (LLDP) is a vendor-neutral link layer protocol used by network devices for advertising their identity, capabilities, and neighbors on a local area network based on IEEE 802 technology.Some vendors have more esoteric proprietary protocols or network discovery mechanisms (such as network broadcasts, etc.), but the most popular protocols are: Discover a layer 2 network topologyįor layer 2 networks, you can use different protocols to discover the network topology. Also, most monitoring tools that use SNMP or other remote monitoring protocols can provide a network map. Federal System Integrator Partnersĭifferent tools can automatically build a network topology map of a layer 2 and/or layer 3 network. HPE FlexFabric and FlexNetwork Switches.
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