HP 6120XG HP ProCurve Series 6120 Blade Switches Advanced Traffic Management G - Page 43

Static Virtual LANs (VLANs) Multiple VLAN Considerations reason, the 6600 discards some packets directed through it for the 6120 switch, resulting in poor performance and the appearance of an intermittent or broken link. The Solution. To avoid the preceding problem, use only one cable or port trunk between the single-forwarding and multiple-forwarding database devices, and configure the link with multiple, tagged VLANs. PC "A" VLAN 1 VLAN 1 Switch VLAN 1& 2 A1 VLAN 2 C1 VLAN 1 & 2 6120 Switch VLAN 2 PC "B" This switch has a single forwarding database. This switch has multiple forwarding databases. Figure 2-10. Example of a Solution for Single-Forwarding to Multiple-Forwarding Database Devices in a Multiple VLAN Environment Now, the 6600 forwarding database always lists the 6120 MAC address on port A1, and the 6600 will send traffic to either VLAN on the 6120. To increase the network bandwidth of the connection between the devices, you can use a trunk of multiple physical links rather than a single physical link. Multiple Forwarding Database Operation If you want to connect one of the switches covered by this guide to another switch that has a multiple forwarding database, you can use either or both of the following connection options: ■ A separate port or port trunk interface for each VLAN. This results in a forwarding database having multiple instances of the same MAC address with different VLAN IDs and port numbers. (See table 2-4.) The fact that the switches covered by this guide use the same MAC address on all VLAN interfaces causes no problems. ■ The same port or port trunk interface for multiple (tagged) VLANs. This results in a forwarding database having multiple instances of the same MAC address with different VLAN IDs, but the same port number. Allowing multiple entries of the same MAC address on different VLANs enables topologies such as the following: 2-20