HP 6400cl, Management Manual, Page: 47 / 664

Static Virtual LANs (VLANs)
Multiple VLAN Considerations
4. If you are managing VLANs with SNMP in an IP network, the VLAN
through which you are managing the switch must have an IP address.
Refer to chapter 7, “Configuring IP Addressing”, in the
Management and
Configuration Guide for your switch.
Multiple VLAN Considerations
Switches use a forwarding database to maintain awareness of which external
devices are located on which VLANs. Some switches, such as those covered
by this guide, have a
multiple forwarding database , which means the switch
allows multiple database entries of the same MAC address, with each entry
showing the (different) source VLAN and source port. Other switch models
have a
single forwarding database , which means they allow only one data-
base entry of a unique MAC address, along with the source VLAN and source
port on which it is found. All VLANs on a switch covered by this guide use the
same MAC address. Thus, connecting a Series 5300XL, 3400cl, or 6400cl
(multiple forwarding database) switch to a single forwarding database switch
where multiple VLANs exist imposes some cabling and port VLAN assignment
restrictions. Table 2-5 illustrates the functional difference between the two
database types.
Table 2-5. Example of Forwarding Database Content
Multiple Forwarding Database
MAC Address Destination
VLAN ID
Destination
Port
0004ea-84d9f4 1 A5
0004ea-84d9f4 22 A12
0004ea-84d9f4 44 A20
0060b0-880a81 33 A20
This database allows multiple destinations
for the same MAC address. If the switch
detects a new destination for an existing
MAC entry, it just
adds a new instance of that
MAC to the table.
Single Forwarding Database
MAC Address Destination
VLAN ID
Destination
Port
0004ea-84d9f4 100 A9
0060b0-880af9 105 A10
0060b0-880a81 107 A17
This database allows only one destination
for a MAC address. If the switch detects a
new destination for an existing MAC entry,
it
replaces the existing MAC instance with
a new instance showing the new
destination.
Table 2-6 lists the database structure of current HP ProCurve switch models.
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