NEWS - Exchange 2010 CAS-Client Access Servers or array servers now LB-Load Balance all internal and external client traffic to Exchange mailbox servers including Outlook MAPI Messaging Application Programming Interface traffic critical to Exchange implementation.

NLB-Network Load Balancing is a means to shift the data stream to other servers or devices depending on a large number of algorithms (rules of thumbs) such as time, protocol, IP address, media and other factors.  The key perceived benefit of NLB is to improve availability (uptime-resiliency), scalability (growth) and dispersion (geographic distribution). 

According to Microsoft, "Network Load Balancing is a clustering technology offered by Microsoft as part of all Windows 2000 Server and Windows Server 2003 family operating systems. NLB uses a distributed algorithm to load balance network traffic across a number of hosts, helping to enhance the scalability and availability of mission critical, IP-based services, such as Web, Virtual Private Networking, Streaming Media, Terminal Services, Proxy, etc. It also provides high availability by detecting host failures and automatically redistributing traffic to operational hosts.  A cluster is a group of independent computers that work together to run a common set of applications and provide the image of a single system to the client and application. The computers are physically connected by cables and programmatically connected by cluster software. These connections allow computers to use problem-solving features such as failover in Server clusters and load balancing in Network Load Balancing (NLB) clusters.

Microsoft Exchange Server 2010 includes a new unified framework for mailbox resiliency that includes new features such as the DAG-Database Availability Group. A DAG is a critical concept is support the functions mentioned above - availability, scalability and dispersion.   According to Microsoft, "A DAG is a group of up to 16 Mailbox servers that host a set of databases and provide automatic database-level recovery from failures that affect individual servers or databases. Exchange 2010 uses the same continuous replication technology found in Exchange 2007. Exchange 2010 combines on-site data replication (CCR) and off-site data replication (SCR) into a single framework which is the DAG." Of key importance is that with DAG's, IT managers can add copies of databases easily and incrementally with automatic management of such as mirror DB-databases provided by Exchange 2010.  For more on DAG's click here. 

OCS-Load Balancing - A load balancer is required in an Enterprise pool that has more than one Enterprise Edition Server. The load balancer provides scalability and availability across multiple servers that are connected to a centralized database on the OCS Back-End Database.  Only one load balancer is required, there can be two logical load balancers-one for the Front End Servers and one for the Web Components Server.  Two are recommended for installations using the Enterprise Edition-Expanded configuration.   Two VIP-Virtual IP addresses are needed for either two logical or separate physical load balancers.  When you configure the load balancer, check with the firewall and DNS administrator for at least one VIP-Virtual IP address and FQDN-Fully-Qualified Domain Name for the load balancer (one for each logical load balancer), as well as a static IP address for every server in the Enterprise device pool.

 *MAPI & MIME - The OCS Front End Server translates the dialed number into canonical format, applies dialing authorization, and selects the appropriate IP-PSTN gateway to route calls.    Prior to any security procedures the SIP message MUST be converted into MIME-Multipart Internet Mail Extension format.  MIME is a standard that allows the embedding of arbitrary documents and other binary data of known types (images, sound, video, and others) into e-mail handled by Internet electronic mail interchange protocols.  Messaging Application Programming Interface (MAPI) is a communications messaging architecture and a COM-Component Object Model based API-Applications Programming Interface for Windows.   MAPI allows client programs to become email messaging-enabled, -aware, or -based by calling (programming term for request) MAPI software subsystem routines that interface with certain messaging servers.  Exchange supports Internet standards e-mail protocols, POP3 and IMAP4.  S/MIME (Secure/Multipurpose Internet Mail Extensions) is a standard for public key encryption and email encapsulated (contained) in MIME.  MIME in simple terms.  Traditional email was based on US ASCII-American Standard Code for Information Interchange designed originally for teletype machines.  MIME redefines the format of messages to allow for (1) textual message bodies in character sets other than US-ASCII, (2)an extensible set of different formats for non-textual message bodies, (3)multi-part message bodies, and (4)textual header information in character sets other than US-ASCII.

 In two weeks - 1/1-2010 - Top-10 Tera Trends fo a New Decade