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Network mapping is the study of the physical connectivity of networks e.g. theInternet. Network mapping discovers the devices on the network and their connectivity. It is not to be confused with network discovery ornetwork enumeration which discovers devices on the network and their characteristics such asoperating system, openports, listeningnetwork services, etc. The field of automated network mapping has taken on greater importance as networks become more dynamic and complex in nature.
Images of some of the first attempts at a large scale map of the internet were produced by theInternet Mapping Project and appeared inWired magazine. The maps produced by this project were based on thelayer 3 orIP level connectivity of the Internet (seeOSI model), but there are different aspects of internet structure that have also been mapped.
More recent efforts to map the internet have been improved by more sophisticated methods, allowing them to make faster and more sensible maps. An example of such an effort is theOPTE project, which is attempting to develop a system capable of mapping the internet in a single day.
The "Map of the Internet Project" maps over 4 billion internet locations as cubes in 3Dcyberspace. Users can addURLs as cubes and re-arrange objects on the map.
In early 2011 Canadian based ISPPEER 1 Hosting created their ownMap of the Internet that depicts a graph of 19,869autonomous system nodes connected by 44,344 connections. The sizing and layout of the autonomous systems was calculated based on theireigenvector centrality, which is a measure of how central to the network each autonomous system is.
Graph theory can be used to better understand maps of the internet and to help choose between the many ways tovisualize internet maps. Some projects have attempted to incorporate geographical data into their internet maps (for example, to draw locations ofrouters andnodes on a map of the world), but others are only concerned with representing the more abstract structures of the internet, such as the allocation, structure, and purpose ofIP space.
Many organizations create network maps of their network system. These maps can be made manually using simple tools such asMicrosoft Visio, or the mapping process can be simplified by using tools thatintegrate auto network discovery with Network mapping, one such example being the Fabric platform. Many of the vendors from theNotable network mappers list enable you to customize the maps and include your own labels, add un-discoverable items and background images. Sophisticated mapping is used to help visualize the network and understand relationships between end devices and the transport layers that provide service. Mostly, network scanners detect the network with all its components and deliver a list which is used for creating charts and maps using network mapping software.[1] Items such as bottlenecks androot cause analysis can be easier to spot using these tools.
There are three main techniques used for network mapping:SNMP based approaches,active probing androute analytics.
The SNMP based approach retrieves data from Router and Switch MIBs in order to build the network map. The active probing approach relies on a series of traceroute-like probe packets in order to build the network map. The route analytics approach relies on information from therouting protocols to build the network map. Each of the three approaches have advantages and disadvantages in the methods that they use.
There are two prominent techniques used today to create Internet maps. The first works on the data plane of theInternet and is called active probing. It is used to inferInternet topology based onrouter adjacencies. The second works on the control plane and infersautonomous system connectivity based onBGP data. A BGP speaker sends 19-byte keep-alive messages every 60 seconds to maintain the connection.
This technique relies ontraceroute-like probing on the IP address space. These probes report back IP forwarding paths to the destination address. By combining these paths one can infer router level topology for a givenPOP. Active probing is advantageous in that the paths returned by probes constitute the actual forwarding path that data takes through networks. It is also more likely to findpeering links betweenISPs. However, active probing requires massive amounts of probes to map the entire Internet. It is more likely to infer false topologies due to load balancing routers and routers with multiple IP address aliases. Decreased global support for enhanced probing mechanisms such assource-route probing,ICMP Echo Broadcasting, andIP Address Resolution techniques leaves this type of probing in the realm of network diagnosis.
This technique relies on variousBGP collectors who collect routing updates and tables and provide this information publicly. Each BGP entry contains aPath Vector attribute called the AS Path. This path represents anautonomous system forwarding path from a given origin for a given set ofprefixes. These paths can be used to infer AS-level connectivity and in turn be used to build AS topology graphs. However, these paths do not necessarily reflect how data is actually forwarded and adjacencies between AS nodes only represent a policy relationship between them. A single AS link can in reality be several router links. It is also much harder to infer peerings between two AS nodes as these peering relationships are only propagated to an ISP's customer networks. Nevertheless, support for this type of mapping is increasing as more and more ISP's offer to peer with public route collectors such asRoute-Views andRIPE. New toolsets are emerging such as Cyclops andNetViews that take advantage of a new experimental BGP collectorBGPMon. NetViews can not only build topology maps in seconds but visualize topology changes moments after occurring at the actual router. Hence, routing dynamics can be visualized in real time. In comparison to what the tools using BGPMon does there is another tool netTransformer able to discover and generate BGP peering maps either through SNMP polling or by converting MRT dumps[2] to agraphml file format. netTransformer allows us also to perform network diffs between any two dumps and thus to reason how does the BGP peering has evolved through the years.[3]WhatsUp Gold, anIT monitoring tool, tracks networks, servers, applications, storage devices, virtual devices and incorporates infrastructure management, application performance management.[4]
