|
Feature |
Product |
Release introduced |
|---|---|---|
|
Network Load Balancing (NLB) - multicast operation |
5320 Series |
Not Supported |
|
5420 Series |
Not Supported |
|
|
5520 Series |
VOSS 8.2.5 |
|
|
Network Load Balancing (NLB) - unicast operation |
5320 Series |
Not Supported |
|
5420 Series |
Not Supported |
|
|
5520 Series |
VOSS 8.2.5 |
Microsoft Network Load Balancing (NLB) is a clustering technology available with the Microsoft Windows 2000, Microsoft Windows 2003, Microsoft Windows 2008, and Microsoft Windows 2012 Server family of operating systems. You can use NLB to share the workload among multiple clustering servers. NLB uses a distributed algorithm to load balance TCP/IP network traffic across a number of hosts, enhancing the scalability and availability of the following mission critical, IP-based services:
web
VPN
Streaming media
Firewalls
Although the switch interoperates with NLB clusters that operate in Unicast mode and Multicast mode, the following restrictions apply:
The software does not support true egress mirroring because packets are mirrored prior to the completion of packet processing, so egress mirrored packets can differ from the packets egressing the port.
Note
To mirror the egress traffic, you can use the NEXT-hop device ingress mirroring to capture the egress packets of the switch.
Inter-VRF routing is not supported between an NLB client and an NLB cluster VLAN in Unicast mode or Multicast mode.
You must configure NLB to use the same mode as the NLB Server.
Static ARP entries are not supported for NLB Unicast or NLB Multicast.
For interoperability with NLB, the switch provides configuration options at the VLAN level.
ARP entries for NLB server IP addresses do not age out when there is still client traffic coming to the NLB servers, even after the NLB servers are no longer reachable.
When the cluster is running in NLB unicast mode, all servers in the cluster share a common virtual MAC address, which is 02-bf-x-x-x-x (where x-x-x-x is the cluster IP address in hexadecimal form). All traffic destined to this MAC address is sent to all the servers in the cluster. The virtual MAC address is specified in the Sender MAC Address field of the Address Resolution Protocol (ARP) reply from the cluster to the switch. ARP responses from the switch are sent to the virtual MAC address (rather than to the hardware MAC address).
You can configure the switch for NLB unicast mode support. After you enable the NLB unicast option, the switch floods traffic destined to the cluster IP address to all ports on the VLAN. Unicast mode supports connectivity to a secondary virtual IP address. For information about software scaling capabilities in unicast mode, see Fabric Engine Release Notes.
When the cluster is running in NLB multicast mode, a multicast virtual MAC address with the format 03-bf-x-x-x-x (where x-x-x-x is the cluster IP address in hexadecimal form) is bound to all cluster hosts but the real MAC address of the network adapter is retained. The multicast MAC address is used for client-to-cluster traffic, and the real MAC address of the adapter is used for network traffic specific to the host server.
You can configure the switch for NLB multicast mode support. When you enable NLB multicast mode on a VLAN, the routed traffic destined to the NLB cluster is flooded by default on all ports of the VLAN. All VLANs support multiple cluster IPs by default. You can connect up to 200 NLB clusters to a single VLAN. For information about software scaling capabilities, see Fabric Engine Release Notes.
Note
Shortest Path Bridging MAC (SPBM) supports NLB Unicast and Multicast modes. For more information on SPBM, see Fabric Basics and Layer 2 Services.