Determining Exchange Server 2003 Placement

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Previous versions of Exchange essentially forced many organizations into deploying servers in sites with greater than a dozen or so users. With the concept of site consolidation in Exchange Server 2003, however, smaller numbers of Exchange servers can service clients in multiple locations, even if they are separated by slow WAN links. For small and medium- sized organizations, this essentially means that one or two servers should suffice for the needs of the organization, with few exceptions. Larger organizations require a larger number of Exchange servers, depending on the number of sites and users. Designing Exchange Server 2003 placement must take into account both administrative group and routing group structure.

Designing Administrative Groups

An Exchange Server 2003 administrative group is a logical assortment of Exchange Servers that are administered by the same IT team. A single administrative group can encompass multiple physical locations, depending on the administrative requirements of the organization. For example, in Figure 4.4, CompanyABC has two administrative groups, one for the IT team in North America, and one for the team in Europe.

Figure 4.4. Multiple administrative groups in Exchange 2003.

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Administrative groups enable the simple delegation of granular administrative rights to specific groups. In CompanyABC's case, this means that specific rights can be granted to the IT team in Europe to administer only European servers, and not North American servers ”and vice versa.

Planning Routing Group Topology

The concept of the routing group in Exchange enables a distinction to be made between administration of servers and the actual physical sites in which servers are located.

NOTE

Administrative groups and routing groups in Exchange 5.5 were not separate concepts, but both existed in the form of the Exchange 5.5 site. Consequently, administrative groups and routing groups in Exchange Server 2003 cannot be separated from each other unless the Exchange organization is running in Exchange 2003 native mode.


Figure 4.4 shows that CompanyABC used multiple routing groups within the two administrative groups that have been created. Subsequently, designing administrative group and routing group structure for an organization simply requires outlining the administrative needs and the physical routing restrictions in place in the organization. In many cases, a single administrative group is all that is required, because single IT teams often manage organizations of this size . On the same thread of reasoning, it is often the case that a single routing group can encompass all the servers in a small organization, especially when taking into account the site consolidation strategies mentioned in the previous sections of this chapter.

Examining Public Folder Design Concepts

The public folder structure in Exchange Server 2003 is, for better or worse , the main storehouse of publicly accessed information in the messaging infrastructure. For example, departmental calendars or contact lists can be stored in Exchange public folders.

The Exchange Server 2003 public folder store is a separate database, which is used to store public folder information. In a small or medium-sized organization, a single public folder store can be created and used. In larger organizations, multiple servers can contain multiple public folder stores, each configured to contain a read/write replica of public folder information for redundancy purposes.

Environment Sizing Considerations

In some cases with small organizations, the number of users is small enough to warrant the installation of all Active Directory and Exchange Server 2003 components on a single server. This scenario is possible, as long as all necessary components ”DNS, a Global Catalog domain controller, and Exchange Server 2003 ”are installed on the same hardware.

Identifying Client Access Points

At its core , Exchange Server 2003 essentially acts as a storehouse for mailbox data. Access to the mail within the mailboxes can take place through multiple means, some of which may be required by specific services or applications in the environment. A good understanding of what these services are and if and how your design should support them is warranted.

MAPI Client Access with Outlook 2003

The "heavy" client of Outlook, Outlook 2003, has gone through a significant number of changes, both to the look and feel of the application, and to the back-end mail functionality. The look and feel has been streamlined based on Microsoft research and customer feedback. Although it might take some getting used to, the layout and configuration is much more efficient, making checking email, scheduling, and other messaging features easier to accomplish.

On the back end, Outlook 2003 improves the MAPI compression that takes place between an Exchange Server 2003 system and the Outlook 2003 client. The increased compression helps reduce network traffic and improve the overall speed of communications between client and server.

In addition to MAPI compression, Outlook 2003 introduces the ability to run in a slow-link mode, which automatically detects slow connections between client and server and adjusts Outlook functionality to match the speed of the link. When a slow link is detected , Outlook downloads only email header information. When emails are opened, the entire email is downloaded, including attachments if necessary. This drastically reduces the amount of bits across the wire that are sent, because only those emails that are required are sent across the connection.

The Outlook 2003 client is the most effective and full-functioning client for users who are physically located close to an Exchange Server. With the enhancements in slow-link functionality, however, Outlook 2003 can also be effectively used in remote locations. The decision about which client to deploy as part of a design should keep these concepts in mind.

Outlook Web Access (OWA)

The Outlook Web Access (OWA) client in Exchange Server 2003 has been revamped and optimized for performance and useability. There is now very little difference between the full function client and OWA. With this in mind, OWA is now an even more efficient client for remote access to the Exchange Server. The one major piece of functionality that OWA does not have, but the full Outlook 2003 client does, is offline mail access support. If this is required, the full client should be deployed. Aside from this, however, the improvements in OWA make this a difficult choice.

Outlook Mobile Access (OMA)

Microsoft anticipates that the wireless messaging market will expand by leaps and bounds in the coming years . The company subsequently has invested heavily in gearing its technologies toward wireless access methods . Exchange Server 2003 is one of those technologies, and the introduction of Outlook Mobile Access (OMA) gives an indication of Microsoft's push into this arena.

OMA enables wireless devices, such as handheld organizers, wireless phones, and other small-screen appliances to have an access method to Exchange mailbox data that is customized to the uniquely small reading areas of these devices. The OMA client enables an optimized mail experience, and is ideal for those types of clients that use wireless devices.

The POP3 Protocol

Exchange Server 2003 enables access to email via the older, but industry-standard POP3 Protocol. POP3 is often used with clients such as Outlook Express and Eudora, and is limited in its functionality beyond basic mail retrieval. If a specific need exists to maintain POP3 functionality, this protocol can be designed into the environment. If there is no distinct need to use it, it should be disabled to minimize potential security risks.

The IMAP Protocol

Similar to POP3, the IMAP protocol is an older industry standard that relates to mail sending and retrieval. Many Unix mail clients, such as PINE, use IMAP for mail. As with the POP3 protocol, unless a specific need exists to support IMAP clients, the IMAP protocol should be disabled.

Simple Mail Transport Protocol (SMTP)

The Simple Mail Transfer Protocol (SMTP) is an industry-standard protocol that is widely used across the Internet for mail delivery. The SMTP protocol is built in to Exchange servers and is used by Exchange systems for relaying mail messages from one system to another, which is similar to the way that mail is relayed across SMTP servers on the Internet. Exchange is dependent on SMTP for mail delivery and uses it for internal and external mail access.

NOTE

Previously, Exchange 5.5 (and earlier) used the X.400 protocol to relay messages internally from one Exchange Server to another. This feature changed in Exchange 2000 and later in Exchange Server 2003, where X.400 is used only for backward compatibility with Exchange 5.5 systems.


By default, Exchange Server 2003 uses DNS to route messages destined for the Internet out of the Exchange topology. If, however, a user wants to forward messages to a smarthost before they are transmitted to the Internet, an SMTP connector can be manually set up to enable mail relay out of the Exchange system. SMTP connectors also reduce the risk and load on an Exchange Server by offloading the DNS lookup tasks to the SMTP smarthost. SMTP connectors can be specifically designed in an environment for this type of functionality.

RPC over HTTP Protocol

The new access protocol added to Exchange Server 2003 is the RPC over HTTP protocol, which enables standard Outlook 2003 access across firewalls. The Outlook 2003 client encapsulates RPC packets into HTTP or HTTPS packets and sends them across standard Web ports (80 and 443), where they are then extracted by the Exchange Server 2003 system. This technology enables Outlook to communicate using its standard RPC protocol, but across firewalls and routers that normally do not allow RPC traffic. The potential uses of this protocol are significant, because many situations do not require the use of cumbersome VPN clients.

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Microsoft Exchange Server 2003 Unleashed
Microsoft Exchange Server 2003 Unleashed (2nd Edition)
ISBN: 0672328070
EAN: 2147483647
Year: 2003
Pages: 393
Authors: Rand Morimoto

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