3Com corebuilder 3500 Implementation Manual page 190

190 C 9: V
HAPTER IRTUAL
LAN
S
Important Considerations
To create an IP interface that can route through a static VLAN, you must:
1 Create a protocol-based IP VLAN for a group of bridge ports. If the VLAN
overlaps with another VLAN at all, define it in accordance with the
requirements of your VLAN mode.
This IP VLAN does not need to contain Layer 3 information. An IP VLAN
with Layer 3 information is a network-based VLAN. See "Network-based
IP VLANs" later in this chapter.
2 Configure an IP routing interface with a network address and subnet
mask, and specify the interface type vlan.
3 Select the IP VLAN index that you want to "bind" to that IP interface.
If Layer 3 information is provided in the IP VLAN for which you are
configuring an IP routing interface, the subnet portion of both addresses
must be compatible. For example:
IP VLAN subnet 157.103.54.0 with subnet mask of 255.255.255.0
IP host interface address 157.103.54.254 with subnet mask of
255.255.255.0
Layer 2 (bridging) communication is still possible within an IP VLAN (or
router interface) for the group of ports within that IP VLAN:
For allClosed VLANs, IP data destined for a different IP subnetwork
uses the IP routing interface to reach that different subnetwork even if
the destination subnetwork is on a shared port.
For allOpen VLANs, using the destination MAC address in the frame
causes the frame to be bridged; otherwise, it is routed in the same
manner as allClosed VLANs.
4 Enable IP routing.
You perform similar steps to create IPX and AppleTalk routing interfaces.
For more information, see the routing chapters in this guide (for routing
protocols such as IP, OSPF, IPX, and AppleTalk).