Dell S50V - page 571

Layer 2 | 571

Since the virtual MAC address is never learned, traffic is forwarded to only one server rather than the

entire cluster, and failover and balancing are not preserved (Figure 25-5).

Figure 25-4. Server Clustering: Multiple ARP Replies

Figure 25-5. Server Clustering: Failover and Balancing Not Preserved

Configuring the Switch for Microsoft Server Clustering

To preserve failover and balancing, the Dell Force10 switch must learn the cluster’s virtual MAC address,

and it must forward traffic destined for the server cluster out all member ports in the VLAN connected to

the cluster. To ensure that this happens, you must configure the command ip vlan-flooding on the Dell

Force10 switch at the time that the Microsoft cluster is configured (Figure 25-6).

As shown in Figure 25-6, the server MAC address is given in the Ethernet frame header of the ARP reply,

while the virtual MAC address representing the cluster is given in the payload. The ip vlan-flooding

command directs the system to discover that there are different MAC addresses in an ARP reply and

associate the virtual MAC address with the VLAN connected to the cluster. Then, all traffic destined for

the cluster is flooded out of all member ports. Since all of the servers in the cluster receive traffic, failover

and balancing are preserved.

VLAN 1 Client

Last ARP Reply

MACS1

Server1:IPS1

MACS2

IPS2

Server2:

Source MAC: MACCluster

Destination MAC: MACClient Source IP: IPS1

Source MAC: MACS1

Type: 0x0806

Pad CRC

Ethernet Frame Header ARP Reply

fnC0027mp

icrosoft Server Cluster: IPCluster

MACCluster

MACS3

IPS3

Server3:

MACS4

IPS4

Server4: