The operation of network management system lies on
a good command of the topological structure in the
whole management network. The auto-discovery of
network topology plays a decisive role in network
management and function analysis. In this paper,
several main network topology discovery technologies
are briefly introduced, and then an improved network
topology discovery algorithm is presented.
Until now, the existing studies about network
topology discovery technology are as follows:
Topology discovery based on arp
Topology discovery based on icmp protocol
Topology discovery based on snmp protocol
The topology discovery based on arp protocol
operates by searching for adjacent devices which can be
further used to identify another devices by taking
advantage of their arp tables, thus building a whole
topology structure. Typical algorithms are topology
discovery algorithm based on a complete arp table put
forward by Breibart[1] and the other based on part of
the arp table by Zhenghai[2]. Having the arp tables with
IP and MAC network address that are lately used and
also valid makes the method quite efficient. While it is
more applicable in local area network as the arp
protocol has scope only within the broadcast network.
Topology discovery based on icmp protocol mainly
adopts ping and traceroute, combining with dns zone
transmission[3]. The application of ping and traceroute
is used in skitter tool of CAIDA for the study of
network topology and can also be employed in any
networks to serve the network topology discovery[4].
But its weaknesses are that the network load would be
increased as it is required to send detected data report to
each node in the network regularly, and that efficiency
would be reduced due to the adverse impacts from the
network security measures and the limited scope to
detect the information.
Topology discovery based on snmp protocol obtains
routing equipment list or host list from mib of routers or
vlan-mib of switches over the snmp protocol[5]. First of
all, the method utilizes the snmp protocol to get the
basic information of the specified network devices and
has them checked. Next, it acquires the detailed
database of the corresponding devices by accessing
different mib objects of various devices. According to
the type of device, more information of the
corresponding device is obtained and these data are
processed. Then from these findings, the method begins
to traverse step by step, and the entire network topology
structure is obtained finally. The search process of the
algorithm is simple, and it is with high efficiency, low
overhead. Now SNMP are usually supported by general
machines. This method is suitable for a wide range of
topology discovery.
The proposed algorithm in this paper is aimed at a
controllable network, at the same time requirement of
topology discovery is complete, accurate and high
efficiency, so the authors choose the topology discovery
based on SNMP protocol.