HP Network Direr Software Products manual Switch Switch4400-6 Port 00-30-1e-c6-40-38

Key Considerations 573

appear on one port on one VLAN and on another port on another VLAN, on the same switch e.g.:

Figure 313 Coexistent MAC Address

This causes 3Com Network Director problems when it tries to construct its map of the network. The algorithm that 3Com Network Director uses to construct the map assumes that the network can be represented by a tree of devices with no loops in the network. However, Figure 313 contravenes this assumption. To the switch, it appears as if there is a loop in the network because MAC A has been learned on 2 different ports. The 3Com Network Director map-building algorithm does not handle loops such as this. Instead the map-building algorithm picks one port for each MAC address and ignores all other ports that it has been learned on. So in the above example, pick port 1 and ignore port 24. However, this may result in 3Com Network Director building a network map that is not completely accurate. In this situation, 3Com Network Director adds the following warning to the Discovery Report. See “The Discovery Report” on page 131.

A device has been seen (or “learned”) on multiple ports of another device. This implies there is a loop in the network. 3Com Network Director may not represent the topology of the network accurately.

Table 84 Device Learned On Multiple Ports

Device Learned On
Multiple Ports	Learned By Device	Ports Learned On
Switch 3300	Switch4400-6	Port 1
		Port 5
00-30-1e-c6-40-38	Switch4400-6	Port 13
		Port 3

This warning will only occur due to particular combinations of network topology and VLAN configuration, and so this situation will be fairly uncommon.