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Lesson 3Sites
ObjectiveDefine Sites and their role in reducing network traffic.

Sites Role in reducing Network Traffic

Using sites and subnets to reduce traffic

site is a combination of one or more Internet Protocol (IP) subnets connected by a high-speed link. By defining a site, you reduce replication traffic across slower links.
Staying within the same site decreases traffic between domain controllers, which means that the network replication is more efficient.
Note that traffic between domain controllers is a problem with replication.
With logon authentication, the traffic is between client computers and a domain controller. Either situation can cause network congestion when taking place across a slow wide area network (WAN) link.
Workstation logon and replication causes increased Active Directory traffic. To address this, you must ensure that Windows 2000 uses the most efficient links and schedules for replication and logon.
Site: A site is one or more IP subnets connected by a high-speed link.
Note that sites are used only when a network spans multiple geographic locations that are connected by slow links. Defining sites is of no use on a local area network that is contained at one physical location.

How a logon request is validated

The location of the domain controller impacts how efficiently a logon request is validated. Let us look at an example:



Validate Logon Request

Benefits of placing servers into sites

Defining sites allows you to configure Active Directory access and replication so that Windows 2000 uses the most efficient links and schedules for replication and logon traffic.
As an administrator, you create sites for two reasons:
  1. To optimize replication traffic
  2. To allow users to connect to a domain controller using a reliable, high-speed connection
In summary, by defining a site, you have better traffic control for both logon and replication, and the network operates more efficiently, especially if it has geographically separate locations connected by slow links.

Sites (physical structure) and domains (logical structure)

As you know, sites are different from domains, and domains and sites are independent of one another. The MouseOver below reviews the difference between the physical and logical structure of your network:
site map domain map
Sites Domain Main Sites Domain Blank

Sites Domains

The independence of physical and logical structures

The physical structures (sites) and logical structure (domains) of Active Directory are independent of each other, which has the following consequences:
The physical structures (sites) and logical structure (domains) of Active Directory are independent of each other, which has the following consequences:
  1. There is no necessary relationship between the physical structure of the network and the domain structure of the network
  2. Active Directory allows multiple domains in a single site in addition to multiple sites in a single domain
  3. There is no necessary connection between site and domain namespaces

The physical structure (sites) and logical structure (domains) of Active Directory are independent of each other, which has the following consequences:
  1. There is no necessary relationship between the physical structure of the network and the domain structure of the network.
  2. Active Directory allows multiple domains in a single site in addition to multiple sites in a single domain.
  3. There is no necessary connection between site and domain namespaces.

In summary

In summary, by defining a site, you have better traffic control for both logon and replication, and the network operates more efficiently, if it has geographically separate locations connected by slow links.
In the next lesson, we will discuss domain controllers and how to place a domain controller in a site.

Sites Domains SiteLink