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Microsoft Network Load Balancing
Network load balancing (NLB) is a clustering functionality that is implemented by Microsoft on Windows 2000 Server and Windows
Server 2003 operating systems (OSs). NLB uses a distributed methodology or pattern to equally split and balance the network traffic
load across a set of servers that are part of the cluster or group. NLB combines the servers into a single multicast group and
attempts to use the standard multicast IP or unicast IP addresses, and MAC addresses to transmit of network traffic. At the same
time, NLB also uses a single virtual IP address for all clients as the destination IP address, which enables servers to join the same
multicast group that is transparent to the clients (the clients do not notice the addition of new servers to the group). The clients use
a cluster IP address to connect to the server. For optimal processing of data packets, NLB enables flooding of traffic over the virtual
local area network (VLAN) ports (for Unicast mode) or a subset of ports in a VLAN (for Multicast mode) to avoid overloading and
effective performance of the servers.
NLB functions in two modes, Unicast mode and Multicast mode. Configure the cluster IP address and the associated cluster MAC
address in the NLB application running on the Windows Server.
•
In Unicast mode, when the server IP address attempts to be resolved to the MAC address using the address resolution protocol
(ARP), the switch determines whether the ARP reply, obtained from the server, is of an NLB type. The switch then maps the IP
address (cluster IP) with the MAC address (cluster MAC address).
•
In Multicast mode, the cluster IP address is mapped to a cluster multicast MAC address you configured using a
static ARP
command. After the NLB entry is learned, the traffic forwards to all the servers in the VLAN corresponding to the cluster virtual
IP address.
NLB Unicast Mode Scenario
Consider a sample topology in which you configure four servers, S1 through S4, as a cluster or a farm. This set of servers connects
to a Layer 3 switch, which connects to the end-clients. The servers contain a single IP address (IP-cluster address of 172.16.2.20)
and a single unicast MAC address (MAC-Cluster address of 00-bf-ac-10-00-01) for load-balancing. Because multiple ports on a
switch cannot learn a single MAC address, the servers are assigned MAC addresseses of MAC-s1 to MAC-s4), respectively, on S1
through S4 in addition to the MAC cluster address. All the servers of the cluster belong to VLAN1.
In Unicast NLB mode, the following sequence of events occurs:
•
The switch sends an ARP request to resolve the IP address to the cluster MAC address.
•
The ARP servers send an ARP response with the MAC cluster address in the ARP header and a MAC address of MAC-
s1/s2/s3/s4 (for servers S1 through S4) in the Ethernet header.
•
The switch associates the IP address with the MAC cluster address with the last ARP response it obtains. Assume that the last
ARP reply is obtained from MAC-s4 (assuming that the ARP response with MAC-s4 is received as the last one). The interface
associated with server, S4, is added to the ARP table.
•
With NLB enabled, after learning the NLB ARP entry, all the subsequent traffic is flooded on all ports in VLAN1.
With NLB, the data frame forwards to all the servers for them to perform load-balancing.
NLB Multicast Mode Scenario
Consider a sample topology in which you configure four servers, S1 through S4, as a cluster or a farm. This set of servers connects
to a Layer 3 switch, which connects to the end-clients. They contain a single multicast MAC address (MAC-Cluster:
03-00-5E-11-11-11).
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Microsoft Network Load Balancing
Содержание S4048-ON
Страница 1: ...Dell Configuration Guide for the S4048 ON System 9 9 0 0 ...
Страница 146: ...Figure 14 BFD Three Way Handshake State Changes 146 Bidirectional Forwarding Detection BFD ...
Страница 477: ...Figure 68 Inspecting Configuration of LAG 10 on ALPHA Link Aggregation Control Protocol LACP 477 ...
Страница 480: ...Figure 70 Inspecting a LAG Port on BRAVO Using the show interface Command 480 Link Aggregation Control Protocol LACP ...
Страница 481: ...Figure 71 Inspecting LAG 10 Using the show interfaces port channel Command Link Aggregation Control Protocol LACP 481 ...
Страница 522: ...Figure 87 Configuring Interfaces for MSDP 522 Multicast Source Discovery Protocol MSDP ...
Страница 523: ...Figure 88 Configuring OSPF and BGP for MSDP Multicast Source Discovery Protocol MSDP 523 ...
Страница 524: ...Figure 89 Configuring PIM in Multiple Routing Domains 524 Multicast Source Discovery Protocol MSDP ...
Страница 528: ...Figure 91 MSDP Default Peer Scenario 1 528 Multicast Source Discovery Protocol MSDP ...
Страница 529: ...Figure 92 MSDP Default Peer Scenario 2 Multicast Source Discovery Protocol MSDP 529 ...
Страница 530: ...Figure 93 MSDP Default Peer Scenario 3 530 Multicast Source Discovery Protocol MSDP ...
Страница 633: ...Policy based Routing PBR 633 ...
Страница 777: ...Figure 119 Single and Double Tag TPID Match Service Provider Bridging 777 ...
Страница 778: ...Figure 120 Single and Double Tag First byte TPID Match 778 Service Provider Bridging ...