Flow Based Mac Learning; Configuring Uplink Ports Within A Port-Based Vlan - Dell PowerConnect B-RX Configuration Manual

Flow based MAC learning

In this release, the cpu-flooding command that disables hardware flooding of unknown unicast,
multicast, and broadcast packets on all VLAN has been added. When using this command,
unknown unicast packets will go to the CPU and will be CPU forwarded. Source MAC learning will be
done by CPU. The first packet for unknown DA will go to the CPU and CPU will program the hardware
on demand. Any supplemental packets will be forwarded by the hardware.This will allow MAC
learning only where necessary and at a system level to allow more than 16k MACs. In addition, a
MAC will be learned only on the port or packet processor it was received.
Enabling CPU flooding
To enable CPU based flooding of unknown unicast, broadcast and multicast packets, enter the
following command at the global configuration level.
BigIron RX(config)# cpu-flooding
To enable flow based MAC learning and CPU flooding for unknown unicast packets only, enter the
following command at the global configuration level.
BigIron RX(config)# cpu-flooding unknown-unicast
To enable CPU based flooding for broadcast and multicast packets, enter the following command at
the global configuration level.
BigIron RX(config)# cpu-flooding multicast
Syntax: [no] cpu-flooding [multicast] [unknown-unicast]
Use the multicast parameter to specify CPU flooding for broadcast and multicast packets.
Use the unknown-unicast parameter to specify CPU flooding for unknown unicast packets only.
NOTE
This command does not erase any multicast or unknown-unicast flooding configuration. If this
command is enabled, then it supersedes the per-vlan configuration.

Configuring uplink ports within a port-based VLAN

You can configure a subset of the ports in a port-based VLAN as uplink ports. When you configure
uplink ports in a port-based VLAN, the device sends all broadcast and unknown-unicast traffic from
a port in the VLAN to the uplink ports, but not to other ports within the VLAN. Thus, the uplink ports
provide tighter broadcast control within the VLAN.
For example, if two ports within a port-based VLAN are Gigabit ports attached to the network and
the other ports in the VLAN are 10/100 ports attached to clients, you can configure the two ports
attached to the network as uplink ports. In this configuration, broadcast and unknown-unicast
traffic in the VLAN does not go to all ports in the VLAN. The traffic goes only to the uplink ports.
The clients on the network do not receive broadcast and unknown-unicast traffic from other ports,
including other clients.
To configure a port-based VLAN containing uplink ports, enter commands such as the following.
BigIron RX(config)# vlan 10 by port
BigIron RX(config-vlan-10)# untag ethernet 1/1 to 1/24
BigIron RX(config-vlan-10)# untag ethernet 2/1 to 2/2
BigIron RX(config-vlan-10)# uplink-switch ethernet 2/1 to 2/2
BigIron RX Series Configuration Guide
53-1001810-01
Other VLAN features
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