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Cisco Wide Area Application Services (WAAS) Software

Cisco WAAS Optimizations for Centralized E-Mail Services

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Cisco Wide Area Application Services (WAAS) allows I/T organizations to better simplify e-mail services infrastructure through consolidation and improve delivery of e-mail services for services that are already centralized. The optimizations provided by Cisco WAAS provides dramatic throughput improvements for remote office users when accessing centralized e-mail servers accessed via MAPI, SMTP, POP3, IMAP, RPC, and any other TCP-based protocol. This document will examine the optimizations provided by Cisco WAAS and how Cisco WAAS enables consolidation and acceleration of e-mail services.

Challenge

Enterprise I/T organizations have been challenged with centralizing distributed server infrastructure due to the need to maintain compliance, improve data protection, and control costs, without compromising the productivity and experience of the remote office user. Accessing applications that are rich in content, such as e-mail, over WAN links with high latency, packet loss, and bandwidth constraints creates performance challenges for end users and can quickly overwhelm existing WAN infrastructure. To overcome those challenges, many I/T organizations have been forced to deploy, manage, and protect local infrastructure at every small to medium remote location, as shown in Figure 1.

Figure 1. Typical Distributed Enterprise Infrastructure Deployment

With Cisco Wide Area Application Services and the Cisco Wide Area Application Engine (WAE) family of hardware appliances and router-integrated network module, enterprise I/T organizations can now safely centralize distributed file, e-mail and application infrastructure into the data center without compromising the performance expectations of the remote office users' , as shown in

Figure 2. Centralized and Consolidated Infrastructure with Cisco WAAS

WAAS Optimizations for Centralized E-Mail Applications

Cisco Wide Area Application Services (WAAS), is a multi-layer application acceleration and WAN optimization solution that improves application performance over the WAN, thus enabling centralization. Acceleration for e-mail applications and the associated protocols is achieved through the following Cisco WAAS optimization features:

• Transport Flow Optimizations (TFO)-TFO provides standards-based, field-proven throughput improvements for TCP-based applications while maintaining packet-network friendliness and safe coexistence with other network nodes communicating using standard TCP implementations. TFO terminates TCP sessions locally and transparently optimizes flows that traverse the WAN, thereby shielding communicating nodes from WAN conditions. TFO includes the following components, each providing specific acceleration for e-mail services:

– Large Initial Windows-client e-mail connections more quickly exit the TCP slow-start phase and enter congestion avoidance, thereby allowing a quicker ramp-up in e-mail throughput

– Window Scaling-Cisco WAAS transparently increases the window capacity of optimized TCP connections to allow more data to be in transit, thereby improving e-mail throughput

– Advanced Congestion Handling-Through intelligent handling of congestion scenarios, Cisco WAAS can more efficiently retransmit lost data when necessary, and return to higher levels of throughput on the network much more quickly, resulting in better e-mail application performance

• Data Redundancy Elimination (DRE)-DRE is an advanced form of network compression that allows Cisco WAAS to maintain a database of data that has been seen previously traversing the network. This information is used to remove redundant transmission patterns from having to utilize the network. For repeated patterns, only instructions need to be sent, and the original message is rebuilt in its entirety by the distant appliance. This enables significant levels of compression and ensures message and application coherency in that the original message is always rebuild and verified by the distant WAE. As DRE is application-agnostic and bidirectional, it is effective regardless of the direction of traffic flow. As such, data patterns that have been identified for one application protocol can be used by other applications, and patterns that have been identified for one direction of traffic flow can be used to remove redundancy for traffic flowing in a different direction. With DRE, e-mails and attachments are stored as previously-seen transmissions, and should redundant segments be seen (i.e. an e-mail being forwarded, or an attachment being sent that has been seen before), significant levels of compression can be achieved.

• Persistent Lempel-Ziv (LZ) Compression-Persistent LZ compression is a standards-based compression with a long-lived connection-oriented compression history that can be employed to further minimize the amount of bandwidth consumed by a TCP flow. LZ compression can be used in conjunction with DRE or independently. LZ compression can provide anywhere from 2:1 to 5:1 compression based on the application being used and data being transmitted. This is especially helpful for data that has not been previously seen and suppressed by DRE.

Figure 3. Cisco WAAS E-Mail Optimization Example

E-Mail Acceleration Example

When an end user is sending or receiving an e-mail, Cisco WAAS applies the appropriate optimizations to improve the performance of the e-mail application, leading to the reduction of bandwidth utilization and dramatically faster remote office user e-mail performance. Below is an example of a common user scenario, showing how Cisco WAAS learns network traffic patterns and optimizes application flows:

1. A user in a remote office connects to a Mail Server and downloads an e-mail that another user from a different remote office has sent him. The message includes a 5MB PowerPoint attachment. As the WAE has never seen this data before, it will begin to learn the traffic patterns from the operation and store the traffic segments locally in DRE. During the operation, not only will the WAE be adding the patterns to its DRE database, it will also be examining the traffic patterns for repeated sequences and eliminate any redundancy found. Alongside the pattern matching, WAAS will also compress data in-flight using LZ compression and optimize the TCP connection on behalf of the client and the server. The result of this operation is that:

• DRE learned new traffic patterns and stored them locally to eliminate redundancy from future transmissions. DRE may have been able to identify repeated sequences even within the transfer and suppressed them

• Persistent LZ compression minimized the size of all messages being exchanged

• TFO improved the ability of the client and server to more efficiently communicate

• The user experienced superior e-mail performance

2. The user then opens the attached presentation and saves the file to his desktop. He then makes several modifications to the file, including new images, new slides, and deleted slides, and then e-mails it back to the user in the other remote office. The operation is completed with LAN like response time, as DRE is able to isolate changes within network transmissions, send instructions to the distant WAE on how to rebuild the message in its entirety, and include the changed byte patterns. Along with the high levels of redundancy elimination, persistent LZ compression and TFO are still applied. In this way, Cisco WAAS is able to safely isolate changes while eliminating redundancy from network traffic patterns, thereby minimizing the amount of bandwidth consumption and providing high levels of throughput across the WAN. The user's e-mail transfer is significantly accelerated across the WAN.

The scenario above is one of many where Cisco WAAS can provide LAN-like application performance while enabling consolidation of e-mail and other servers. In the scenario above, should the e-mail have been sent to a large group of users in the same location, the download performance of the e-mail for each subsequent user would be LAN-like and require minimal bandwidth consumption thanks to the optimization capabilities of Cisco WAAS.

Optimized E-Mail Protocols and Applications

Cisco WAAS devices automatically discover one another during the establishment of the client to server connection. No explicit configuration for e-mail optimizations is required, as the WAEs classify application protocols and apply optimizations automatically based on the application protocol. Cisco WAAS provides out-of-the-box, preconfigured optimization policies for a number of e-mail protocols/applications, and facilities to create new policies should an e-mail application be using non-standard ports or protocols. The e-mail protocols Cisco WAAS automatically identifies and optimizes includes:

• Messaging Application Programming Interface (MAPI)-used extensively by Microsoft Exchange Server and Outlook clients. Cisco WAAS provides optimizations for MAPI and the various server and client configurations, including cached mode

• Standard e-mail and messaging protocols-including Post Office Protocol v3 (POP3), Simple Mail Transfer Protocol (SMTP), and Internet Message Access Protocol v4 (IMAP4), Network News Transfer Protocol (NTTP), Quick Mail transfer Protocol (QMTP)

• Web-based e-mail-including Outlook Web Access (OWA)

• Other mail systems-including Lotus Notes, Notes RPC, and HP OpenMail

Figure 4 below shows typical improvement found with Microsoft Exchange 2003 and Microsoft Outlook 2003 (with Cached Mode), and Figure 5 below shows typical improvement found without cached mode. Both figures depict the send and receive (uploading and downloading both) of a 5MB attachment over a T1 (1.5Mbps) with 80mS of round-trip latency:

Figure 4. Figure 4. Cisco WAAS Optimization of Microsoft Exchange 2003 and Outlook 2003 (with Cached Mode)

Figure 5. Figure 5. Cisco WAAS Optimization of Microsoft Exchange and Outlook (without Cached Mode)

Summary

Cisco WAAS provides the tools necessary for I/T organizations to safely centralize distributed e-mail servers into the data center and provide e-mail acceleration to remote office users, thereby improving the performance of centralized e-mail services in WAN environments. By applying intelligent optimizations such as LZ compression, Transport Flow Optimization (TFO), and Data Redundancy Elimination (DRE) to e-mail application protocols, Cisco WAAS provides remote office users with a LAN-like experience when working with consolidated e-mail servers.