3Com MSH 1005 User Manual - page 95
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VLANs and the Switch 1005
The Switch 1005 supports port-based VLANs, where a VLAN consists of
a set of switch ports. Each switch port can only belong to one VLAN at
a time, regardless of the device to which it is attached.
Each Switch 1005 can support up to 16 VLANs. However, you can have
more than 16 VLANs in your entire network by connecting the 16
Switch VLANs to other VLANs using a router.
The Default VLAN
In any network setup, VLAN 1 is the Default VLAN. The Default VLAN is
the only VLAN which allows an SNMP Network Manager to access the
management agent of the unit. On a new Switch, all the ports belong
to VLAN 1. If the devices attached to a port should belong to another
VLAN, you need to use the VLAN Setup screen to place the port in that
VLAN. For more information about the VLAN Setup screen, see
on page 4-12
.
Connecting VLANs to a Router
If the devices in a VLAN need to talk to devices in a different VLAN,
each VLAN requires a connection to a router. Communication between
VLANs can only take place if they are all connected to the router. A
VLAN not connected to a router is isolated.
In the Switch 1005, VLANs are typically connected to routers using
backbone ports
. Backbone ports have the following attributes:
■
Addresses received on backbone ports are not stored in the Switch
Database.
■
Frames with unknown addresses are forwarded to the backbone ports.
If you connect a Switch 1005 to a router using backbone ports, you
need to specify one backbone port for each VLAN connected to the
router.