Network load balancer:

It is installed on many web servers with same iis configuration and iis contents

1. Over view of architecture

2. Installation

3. configuring

4. content replication and configuration replication

For every web server the network adapter is there and it is assigned with some IP address

And every computer is having unique mac address and ip address

Here Network adapter uses the MAC address for communication

When NLB is installed it will create a virtual mac address and it is attached to network adapter

in addition to NIC mac address there will be another MAC address i.e. Virtual MaC Address (Fake)

if you install NLB on different servers, then all the servers are in same NLB cluster then then all the servers are having same virtual MAC address

When the request came to virtual IP address then the all the computers that having the virtual MAC address will pick the request and NLB will decide the which server needs to process. and other server requests will be discarded.

When any server is not responding other servers in NLB is take care of the requests

Installation: go to server manager, features, add feature and check the nlb , install it

after installation go to nlbmgr from run and create new cluster with name as localhost as it takes local configuration, click on next and create a cluster IP address, give the ip address , use the subnet mask ,click on next, it have network address it is the MAC Address

NLB will operate on all ports.

we can add/edit rule

we can allow the requests from ports from our interest like 80 to 80 or 80 to 443.

By default, NLB allows all ports.

Affinity is Single

We have many webservers serving the request. When the user sends the request and session is created and session id is send to browser along with content

after that if user requested again with the same session id , then nlb routes the request to other server where the session is not stored, then web page comes for user to re login.

Its issue, so affinity is having 3 modes

1. NONE: every time user requested the requested to redirected to new server

this is the best performance mode; it is not compatible with in memory session state

But we can access the session by keeping the session ids in database

2.Single:this is done on clients IP address, at first time clients request, NLB remembers the ip address , after that every requests from that IP address NLB sends to same server

session state is stored in Memory, moderate performance

if the clients are going through proxy address where the clients are from the large network, then client will send requests from 2 or 3 ip address. so at that time it will be a problem

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for intranet where the proxies are not used, it is fine

3. Network: worst performance

Whenever client comes from some network, it is routed to one server,

If the requests are coming from same network, then the requests ARE routed to same server

It is used for internet connections

If we have web farm, we need the iis configurations sync with all servers

We can use XCOPY or Robocopy to do the configuration.

When we do the configuration change for one iis, we can manually replicate these changes in the other servers using XCOPY, robocopy

or we can have the shared configuration in one place and it is shared by multiple servers

Another option is MSDeploy.exe tool for content replication and Sync IIS settings and it is free.

For commercial products, go to repliweb.com

Repliweb.com web deployment tool

Regards,

Chaitanya