Foundry Networks Switch and Router Installation And Configuration Manual page 1012

Foundry Switch and Router Installation and Configuration Guide
Layer 3 Policies
Layer 3 policies are rules that control transmission and receipt of packets based on Layer 3 routing protocol
information in the packets. You can configure the following types of Layer 3 policies:
• Protocol-based VLANs
• IP access policies (same as IP filters)
• Router acceleration policies (IP and IPX switching policies)
Protocol-Based VLANs
Within an 802.1d port-based VLAN, you can configure protocol-based VLANs that define Layer 3 broadcast
domains for specific protocols. By configuring a port as a member of a protocol VLAN, you establish a forwarding
policy for that port.
For example, if you have a port-based VLAN that contains ports 1 – 12, you can configure some or all of the ports
in the VLAN as an AppleTalk protocol VLAN. AppleTalk broadcast traffic received on one of the ports in the
AppleTalk VLAN is broadcast to the other ports in the AppleTalk VLAN, but not to ports outside the AppleTalk
VLAN.
When a port in protocol-based VLAN receives a packet, the device examines the Layer 3 information in the packet
to determine whether the packet type is the same as the protocol type of the VLAN.
• If the packet is the same type as the protocol of the VLAN, the device forwards the packet.
• If the packet is another protocol type, the device drops the packet.
For example, when a port in an AppleTalk VLAN receives an AppleTalk packet, the port forwards the packet. The
same port drops IPX packets, unless the port also is a member of an IPX VLAN.
IP sub-net and IPX network VLANs are similar, except for these VLAN types the device examines the IP sub-net
or IPX network address.
• If the IP sub-net or IPX network address matches the address of the IP sub-net VLAN or IPX network VLAN,
the device forwards the packet.
• If the sub-net or network address does not match the VLAN, the device drops the packet.
See "Configuring Virtual LANs (VLANs)" on page 25-1 for VLAN configuration rules and examples.
Actions
A Foundry device forwards a packet if its Layer 3 protocol information matches the protocol VLAN's protocol type,
IP sub-net, or IPX network; otherwise, the policy drops the packet.
Scope
The forwarding policy of a port-based VLAN applies only to that VLAN.
Syntax
Use the following CLI commands or Web management interface panels to configure VLAN policies.
Scope
VLAN type
NOTE: The untagged command applies only if you are removing 802.1q tagging from the ports in the VLAN.
802/1q tagging allows a port to be a member of multiple port-based VLANs. Ports in a port-based VLAN are
tagged by default. The default tag is 8100 and is a global parameter.
C - 8
Table C.5: VLAN Policies
CLI syntax
BigIron(config)# vlan <vlan-id> by port
BigIron(config-vlan-1)# [untagged]
ethernet <portnum > [to | ethernet <portnum>]
Web management links
Configure->VLAN->Port
December 2000