To force the virtual server packets to take a hardware switch path, configure a MAC address static entry in the Filter Database (FDB). If the destination MAC is multicast (the Group bit is set), use the set mac multicast command, optionally specifying a port-list that further scopes the flooding, to force the forwarding traffic to use the hardware path.
Network Load Balancing – Multicast Mode
- Create a Static MAC Address Entry for multicast mac tied to ports and vlan
set mac multicast 03-bf-xx-xx-xx-xx <vlan> ge.1.1-2
So a packet with a destination MAC address of 03:xx:xx:xx:xx:xx is forwarded and replicated to the ports defined in the ‘set MAC multicast’ command. All cluster servers receive exact duplicates of this packet. Since static entries are performed in hardware and directed to specific ports, performance is increased by removing unnecessary flooding to all group ports.
N.B. If there are switches in the layer 2 path between the users and the server cluster then the mac must be configured on all uplinks that egress towards the server.
- The router must have a static ARP entry binding the Virtual-IP to the desired Multicast MAC address.
arp 10.1.1.1 03.bf.xxxx.xxxx arpa
Alternately, you can just turn on multicast arp learning under the VLAN interface:
Network Load Balancing – Unicast Mode
The unicast as multicast feature causes unicast searches in the filter data base to match on statically configured multicast entries using hardware forwarding. When unicast as multicast is enabled on the device, a lookup is performed to determine if the unicast address has also been configured for multicast on the device. If a multicast address is found, packets are hardware forwarded out the configured VLAN and port(s) as defined in the static multicast configuration by extending the search phase of the Layer 2 lookup to match an unlearned destination MAC address against static multicast MAC entries. The unicast as multicast feature is configured by:
Support for unicast NLB in hardware extends the “search” phase of the Layer 2 lookup in an attempt to match an unlearned destination MAC address against static multicast MAC entries. In order to accomplish this, the address will be temporarily modified for the lookup by OR’ing in the MAC multicast bit. This means that a cluster address of “02-03-04-05-06-07” (unicast address) will be configured in the switch as “03-03-04-05-06-07” (multicast address).
- Use the set mac multicast command to specify the MAC address to be treated as a multicast address, specifying the VLAN and egress port(s) to use.
- Using the set mac unicast-as-multicast command, in any command mode, to enable static unicast MAC addresses to be treated as multicast addresses on this device
set mac unicast-as-multicast enable
N.B. The unicast mac is not learned in the switch.
set mac multicast 02:bf:01:01:01:01 1 ge.2.2
Warning: Unicast address converted to multicast 03-BF-01-01-01-01