Routing Between Vlans - 3Com CoreBuilder 2500 User Manual

2-8 C 2: VLAN
HAPTER
Routing Between
VLANs
C B 2500 S
S ON THE ORE UILDER
When the subnetwork address of an IP packet does not match any
subnetwork address of any defined IP VLAN in the system, the system
floods the data to all of the IP VLANs that share the source switch port. In
this example, the shared source port is port 6.
Stations in two different VLANs communicate only by routing between
them. The CoreBuilder 2500 system supports internal routing among IP,
IPX, and AppleTalk VLANs. If VLANs are configured for other routable
network layer protocols, they communicate only through an external
router.
You configure routing protocol interfaces based on a VLAN defined for
that protocol. To assign a routing interface, you first create a VLAN for
that protocol and then associate it with that interface.
For example, to create an IP interface that routes through a VLAN:
1 Create an IP VLAN for a group of switch ports.
This IP VLAN does not need to contain Layer 3 information unless you
want to further restrict flooding according to the Layer 3 subnetwork
address.
2 Configure an IP interface with a network address, subnet mask,
broadcast address, cost, and type (
IP interface.
If Layer 3 information is provided in the IP VLAN for which you are
configuring an IP interface, the subnetwork portion of both addresses
must be the same.
For example:
IP VLAN subnetwork 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
The group of ports within an IP VLAN or router interface can
communicate at the Layer 2 (bridging) level. IP data uses the IP routing
interface to reach a different IP subnetwork, even if the destination
subnetwork is on a shared port.
YSTEM
). Select an IP VLAN to bind to that
vlan