Protocol-Based Vlans; Important Considerations - 3Com 4007 Implementation Manual

280 C 14: V
HAPTER IRTUAL
Protocol-based
VLANs
Important
Considerations
LAN (VLAN )
S S
For Multilayer Switching Modules, protocol-based VLANs enable you to
use protocol type and bridge ports as the distinguishing characteristics for
your VLANs.
When you create this type of VLAN interface, review these guidelines:
If you plan to use the VLAN for bridging purposes, select one or more
protocols per VLAN. Select them one protocol at a time.
If you plan to use the VLAN for routing, you can select one or more
protocols per VLAN, one protocol at a time, and subsequently define a
routing interface for each routable protocol that is associated with the
VLAN. You can perform routing as follows:
You can route between VLANs defined on Multilayer Switching
Modules.
You can use a Multilayer Switching Module to route between
VLANs that are defined on Layer 2 modules.
The Multilayer Switching Modules support routing for three protocol
suites: IP, IPX, and AppleTalk.
To define a protocol-based VLAN interface, specify this information:
The VID, or accept the next-available VID.
The bridge ports that are part of the VLAN interface. (If you have
trunk ports, specify the anchor port for the trunk.)
The protocol for the specified ports in the VLAN.
Tag status (none or IEEEE 802.1Q). IEEE 802.1Q tagging must be
selected for ports that overlap on both port and protocol (for
example, if two IPX VLANs overlap on port 3).
The name of this VLAN interface.
If you use IP as the protocol and also specify a layer 3 address, the
protocol-based VLAN becomes a network-based VLAN.
You can either configure network-based IP VLANs (IP VLANs with unique
Layer 3 IP addresses) or you can define a single protocol-based VLAN with
the protocol type IP and then define multiple IP routing interfaces for that
VLAN. For more information on network-based VLANs, see
"Network-based IP VLANs" later in this chapter.