ASSIGNMENT:

To discover the network 130.49.65.0 via the seed router.

METHOD:

To aid in the search, a script file was built to retrieve information from SNMP objects.

SOURCES:

* RFC 1213 (MIB-II)

* RFC 1493 (Bridge MIB)

The RFC 1213 MIB was used to determine information such as the names of the devices that make up the network, their MAC addresses, interface numbers, system name, number of ports. The RFC 1493 MIB was used to determine the topography of the network.

From the RFC 1213 MIB, the following fields were used for information in the 130.49.65.0 system:

* system.sysDescr.0

* system.sysObjectID

* system.sysName.0

* at.atTable.atEntry.atPhysAddress

The instance number was determined by searching 130.49.54.1 in the at.atTable.atEntry.atPhysAddress fields of the output file of an SNMPWALK command of network 130.49.65.0. The result was that 24 - 130.49.65 devices were found with instance 9. A separate file listing was created for each at.atTable.atEntry.atPhysAddress of the 24 devices for later use in determining the topography of the network.

After realizing that there are 24 devices that are attached to the seed router (130.49.65.232 - 130.49.65.254), each device was investigate individually.

The script file was then revised to output the information of each device to a separate output file.

For each script output device file, the dot1dBridge.dot1dTp.dot1dTpFdbTable.dot1dTpFdbEntry.dot1dTpFdbAddress was editted and reduced to fields, keeping only the Octet String- (hex) field of as many of the 24 devices that supported snmp. It was determined that these fields are the MAC addresses of the neighboring devices that are in the presently investigated devices ARP table.

It was also noted that the physical address from the dot1dBridge.dot1dTp.dot1dTpFdbTable.dot1dTpFdbEntry.dot1dTpFdbAddress field of each neighboring device and searched for these addresses. This led to the dot1dBridge.dot1dTp.dot1dTpFdbTable.dot1dTpFdbEntry.dot1dTpFdbPort numbers, which indicated the port number where the device communicates with the neighboring device.

For example, in searching for the neighboring devices of device 130.49.65.233, searching its output file for each of the other 24 devices. Searching first for 08 00 4E 11 50 D9, which is the MAC address for device 130.49.65.232, and found a match:

Name: dot1dBridge.dot1dTp.dot1dTpFdbTable.dot1dTpFdbEntry.

dot1dTpFdbAddress.8.0.78.17.80.217

Octet String- (hex): 08 00 4E 11 50 D9

Then .8.0.78.17.80.217 explored and found a match with:

Name:dot1dBridge.dot1dTp.dot1dTpFdbTable.dot1dTpFdbEntry.dot1dTpFdbPort.8.0.78.17.80.217

Integer: 27

This indicates that device 130.49.65.233 can talk to device 130.49.65.232 through device 130.49.65.233s Port 27.

To piece the network puzzle together, the process of elimination was used to determine the layout of the network, i.e., starting with the seed router, determined the device that branched from the seed, and continued the process to the end devices.

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ASSIGNMENT:

To discover the network 136.142.100.0 via the seed router.

METHOD:

Since the procedure used in discovering the topography of network 130.49.65.0 worked well, repeat the procedure for discovering the topography of network 136.142.100.0.

The main device of network 136.142.100.0 is 136.142.100.244 (Cisco Systems WS-C5000), and that it communicates to its neighboring devices via its ports.