Configuring and managing ports and VLANs 127
Nortel WLAN—Security Switch 2300 Series Configuration Guide

Restricting layer 2 forwarding among clients

By default, clients within a VLAN are able to communicate with one another directly at Layer 2. You can enhance
network security by restricting Layer 2 forwarding among clients in the same VLAN. When you restrict Layer 2
forwarding in a VLAN, WSS Software allows Layer 2 forwarding only between a client and a set of MAC addresses,
generally the VLAN’s default routers. Clients within the VLAN are not permitted to communicate among themselves
directly. To communicate with another client, the client must use one of the specified default routers.
To restrict Layer 2 forwarding in a VLAN, use the following command:
set security l2-restrict vlan vlan-id
[mode {enable | disable}] [permit-mac mac-addr [mac-addr]]
You can specify multiple addresses by listing them on the same command line or by entering multiple commands.
Restriction of client traffic does not begin until you enable the permitted MAC list. Use the mode enable option with
this command.
To change a MAC address, use the clear security l2-restrict command to remove it, then use the set security l2-restrict
command to add the correct address.
clear security l2-restrict vlan vlan-id
[permit-mac mac-addr [mac-addr] | all]
To display configuration information and statistics for Layer 2 forwarding restriction, use the following command:
show security l2-restrict [vlan vlan-id | all]
The following commands restrict Layer 2 forwarding of client data in VLAN abc_air to the default routers with MAC
address aa:bb:cc:dd:ee:ff and 11:22:33:44:55:66, and display restriction information and statistics:
WSS# set security l2-re strict vlan abc_air mode enable permit-mac aa:bb:cc:dd:ee:ff
11:22:33:44:55:66
Note. For networks with IP-only clients, you can restrict client-to-client forwarding using
ACLs. (See “Restricting client-to-client forwarding among IP-only clients” on page 515.)
Note. There can be a slight delay before functions such as pinging between clients
become available again after Layer 2 restrictions are lifted. Even though packets are
passed immediately once Layer 2 restrictions are gone, it can take 10 seconds or more for
upper-layer protocols to update their ARP caches and regain their functionality.