FTOS Configuration Guide for the C-Series - Force10 Networks

Restricting Layer 2 Flooding
Restricting Layer 2 Flooding is supported only on platform e
When Layer 2 multicast traffic must be forwarded on a VLAN that has multiple ports with different speeds
on the same port-pipe, forwarding is limited to the speed of the slowest port. Restricted Layer 2 Flooding
prevents slower ports from lowering the throughput of multicast traffic on faster ports by restricting
flooding to ports with a speed equal to or above a link speed you specify.
For example, if a VLAN that has an (auto-negotiated) 100M port and a 1G port on the same port-pipe, and
you enable Restricted Layer 2 Flooding with a minimum speed of 1G, multicast traffic is only flooded on
the 1G port.
Enable Restricted Layer 2 Flooding using the command restrict-flooding from INTERFACE VLAN
mode.
In combination with restrict-flooding, you can use the command mac-flood-list from CONFIGURATION
mode, without the min-speed option, to allow some specific multicast traffic (identified using a MAC
address range you specify) to be flooded on all ports regardless of the restrict-flooding configuration.
Conversly, if you want all multicast traffic to be flooded on all ports, but some specific traffic to be
restricted, use mac-flood-list with the min-speed option, but without restrict-flooding configured. This
configuration restricts flooding only for traffic with destination multicast MAC addresses within the
multicast MAC address range you specify.
In Figure 117, flooding of unknown multicast traffic is restricted to 1G ports on VLAN100 using the
command restrict-flooding. However, the command mac-flood-list allows traffic with MAC addresses
01:01:e8:00:00:00 to 01:01:e8:ff:ff:ff to be flooded on all ports regardless of link speed.
Figure 117 Restricting Layer 2 Multicast Flooding over Low Speed Ports
Force10(conf)#$1:01:e8:00:00:00 ff:ff:ff:00:00:00 vlan 100-200,300
Force10#show run | find mac-flood-list
mac-flood-list 01:01:e8:00:00:00 ff:ff:ff:00:00:00 vlan 100-200,300
[output omitted]
Force10(conf)#interface vlan 100
Force10(conf-if-vl-100)#restrict-flooding multicast min-speed 1000
Force10(conf-if-vl-100)#show config
!
interface Vlan 100
restrict-flooding multicast min-speed 1000
no shutdown
Force10(conf-if-vl-100)#
208 Layer 2