Cisco Wide Area Application Services (WAAS) V4.0 Technical Overview [Small & Medium Business Data Center]

Cisco Wide Area Application Services (WAAS) V4.0 Technical Overview

Executive Summary

Enterprise organizations face numerous challenges to the delivery of applications and critical business data to the enterprise edge. As the global workforce continues to become more distributed, providing adequate service levels throughout the organization becomes increasingly difficult, causing IT organizations to deploy costly and difficult-to-manage infrastructure at each location, including file services, e-mail, video, software distribution, print services, and more. With continuous pressure from industry and federal regulation, IT organizations now face the significant challenge of consolidating this costly infrastructure to improve data protection and compliance with government and industry regulations while somehow maintaining the service level the distributed workforce has come to expect. Furthermore, as applications continue to become more complex and robust in network requirements, delivering applications and application information to the enterprise edge becomes increasingly challenging. Cisco Wide Area Application Services (WAAS) is a new solution that facilitates application delivery and infrastructure consolidation while taking advantage of existing capital and operational assets.

Challenge

IT budgets are not increasing with the growing expectations executives have on IT resources. Almost every IT organization that manages a distributed infrastructure wants to consolidate costly remote-office infrastructure to contain capital and operational expenditures. Furthermore, as applications continue to evolve and become larger and more complex, the network load created grows and the performance characteristics of the WAN affect application delivery even more. The challenges of data-retention policies, business continuance, disaster recovery, and compliance requirements further exacerbate the problem, given a heavily distributed infrastructure and already overburdened WAN environment. Having a centralized IT infrastructure enables operational and capital cost savings while streamlining data-protection processes.

Many vendors have attempted to solve such problems with point products that did not effectively allow IT organizations to take advantage of existing investment in network intelligence.

Cisco WAAS Overcomes the WAN

The Cisco® Wide Area Application Services (WAAS) solution couples application acceleration technologies with WAN optimization techniques to solve the application delivery dilemma-facilitating consolidation of distributed servers and storage, improving performance of already centralized services, and maintaining performance levels for services that are being centralized. Cisco WAAS is deployed on a device on each side of the WAN, a Cisco Wide Area Application Engine (WAE), that provides application-specific acceleration and WAN optimization capabilities. The Cisco WAE engines, shown in Figure 1, are available as router-integrated network modules or as standalone appliances, and are deployed out of the data path in the data center and in the remote branch office to enable high availability, scalability, and fail-through operation.

With Cisco WAAS, IT organizations are better positioned to:

• Centralize costly distributed IT capital resources such as servers and storage into the data center

• Improve throughput and delivery of applications and application data to the enterprise edge

• Increase efficiency and control bandwidth utilization for existing WAN connections

• Maintain remote-office user application performance expectations

Cisco WAAS facilitates such benefits through a series of optimizations that are not only safe to all applications, but also transparent to clients, servers, and the network itself:

• Robust application-specific and protocol-specific acceleration-Cisco WAAS mitigates application layer performance challenges such as latency and bandwidth utilization through protocol acceleration, read-ahead, operation batching, multiplexing, and safe caching. The result is full correctness with protocol specification, full coherency of data, and a dramatically improved user experience when compared with native WAN access.

• Advanced protocol-agnostic network compression-Cisco WAAS is capable of compressing data in-flight using long-lived compression techniques including standards-based compression and cross-protocol data suppression. The result is a significant minimization of network bandwidth consumption and improved application throughput.

• Network-friendly throughput-improvement technologies-Cisco WAAS provides optimizations to TCP to improve WAN utilization efficiency and handling of WAN conditions, including packet loss, congestion, and recovery. The result is that communicating nodes are shielded from problematic WAN conditions, and Cisco WAAS manages these conditions with optimizations to improve throughput, performance, and response times.

With Cisco WAAS, virtually every TCP-based application can benefit from the network and application-specific acceleration techniques, including Internet and intranet applications, databases, file services, file transfer, e-mail, data protection, remote desktop applications, client-server applications, data protection, and many others.

Figure 1. Cisco WAAS Hardware Family

Cisco WAAS facilitates infrastructure consolidation while improving WAN utilization efficiency and application delivery through the following application acceleration and WAN optimization features:

• Cisco WAAS Transport Flow Optimization (TFO)-Cisco WAAS provides optimizations that help improve TCP behavior in problematic WAN conditions to alleviate challenges associated with packet loss, congestion, recovery, and long fan networks (LFNs). With Cisco WAAS TFO, communicating nodes are shielded from WAN conditions, and WAE devices manage WAN conditions on behalf of the nodes to ensure that available capacity can be used to advantage, the effect of packet loss and congestion is mitigated, and throughput is increased. TFO maintains packet-network friendliness and safe coexistence with other network nodes communicating using standard TCP implementations.

• Cisco WAAS Data Redundancy Elimination (DRE)-DRE is a bidirectional database of blocks of data seen within TCP byte streams. DRE inspects incoming TCP traffic and identifies data patterns. As patterns are identified and added to the DRE database, they can then be used in the future as a compression history, and repeated patterns are replaced with very small signatures that instruct the distant device how to rebuild the original message. With DRE, bandwidth consumption is minimized, and latency associated with transferring data is also minimized because fewer packets need to be exchanged. DRE maintains full application and protocol coherency and correctness because the original message rebuilt by the distant WAE is always verified for accuracy at multiple levels and is application independent. Patterns that have been learned from one application flow can be used when another flow-even if using a different application-is seen. DRE can provide from 2:1 to 100:1 compression based on application, data, and workload.

• Persistent Lempel-Ziv (LZ) compression-Cisco WAAS implements LZ compression with a connection-oriented compression history to further minimize the amount of bandwidth consumed by a TCP connection. Persistent LZ compression, which can be used in conjunction with DRE or independently, provides from 2:1 to 5:1 compression based on the application used and data transmitted, in addition to any compression offered by DRE.

• Application Traffic Policy (ATP)-ATP is a robust acceleration and optimization management tool gives administrators the flexibility and control necessary to configure how Cisco WAAS handles specific application protocols. Cisco WAAS ships with default policies for more than 150 different traffic types and more than 25 application groups, and administrators can easily modify these existing policies or create new policies to match other application flows found in their environment.

• Industry-leading Wide Area File Services (WAFS) Functionality-Cisco WAAS builds upon the robust WAFS capabilities provided by the Cisco WAFS Family. Through protocol-specific optimizations, safe caching and data validation, read ahead, prediction, write-behind, multiplexing, and pipelining, Cisco WAAS provides extensive file services acceleration for Common Internet File System (CIFS) clients at the network edge, and can safely overcome protocol-specific performance limitations such as latency, data transfer, and bandwidth consumption. With Cisco WAAS acceleration, remote-office users receive LAN-like access to centralized file-server data, and with disconnected mode of operation, continuous ability to read files during periods of prolonged disconnection. Cisco WAAS also provides Windows-compatible print services that support "point-and-print" and centralized driver distribution for environments that prefer branch office print services. For those environments where centralized print servers are preferred, Cisco WAAS can also optimize that traffic as well. Furthermore, application acceleration technologies can also take advantage of the throughput improvements and compression provided by Cisco WAAS WAN optimization components when information must be transferred or messages must be exchanged across the WAN.

• Extensible application platform-Cisco WAAS is designed to meet current and future application delivery and infrastructure consolidation challenges. The modular software architecture provided by Cisco WAAS allows for additional robust application-specific adapters, WAN optimization components, or transparent integration of other optimization layers, thereby providing investment protection.

• Deployment flexibility and availability-Cisco WAAS is the only application-delivery platform today that offers deployment flexibility, availability, and service transparency. Cisco WAAS integrates transparently with clients, servers, and the network to preserve application configuration and network features. Network interception technologies such as the Web Cache Communication Protocol Version 2 (WCCPv2), policy-based routing (PBR), and server-load-balancing (SLB) platforms such as the Content Services Module (CSM) and ACE Series Application Control Engine for the Cisco Catalyst® 6500 series switchfacilitate fail-through operation with high availability, scalability, and load balancing. Additionally, Cisco WAAS can be deployed physically in-path using a network interface card (NIC) with fail-to-wire capabilities. Cisco WAAS transparency helps IT organizations maintain capital and operational investment in value-added network features such as optimized routing and path selection, quality of service (QoS), Network-Based Application Recognition (NBAR), NetFlow, firewall policies, and others.

• Network transparency-Cisco WAAS provides transparent optimizations and preserves original packet header information critical to network feature operation, including the source and destination IP and TCP information, allowing intermediary routers, switches, and firewalls to continue to perform functions against optimized packets such as classification, prioritization, access control, queuing, control, NetFlow, and routing decisions. Simply put, Cisco WAAS provides transparency necessary to allow value-added features provided by Cisco IOS to continue to operate. When coupled together, Cisco WAAS and IOS provide the most feature-rich framework for providing an application-optimized network infrastructure.

• Industry-leading scalability-Cisco WAAS, coupled with the Application Control Engine (ACE) module for the Catalyst 6500 series switch, provides WAN optimization and application acceleration scalability - up to 16Gbps of throughput and 4 million concurrent TCP connections. Cisco ACE provides not only a scalable off-path mechanism for distributing load amongst Cisco WAAS WAEs in the data center, but also additional application optimization, availability, security, and virtualization features.

Figure 2. Cisco WAAS and IOS Provide Industry-Leading Framework for Application Optimization

The following sections discuss each of the advanced features of the Cisco WAAS solution.

Deployment Flexibility

Cisco WAAS application acceleration and WAN optimization is tightly coupled with the packet network. Through the use of WCCPv2, PBR, or the SLB technologies such as the Cisco Catalyst 6000 CSM or ACE Module, Cisco WAAS integrates transparently into the packet network, requiring no changes to clients, servers, or network features. Cisco WAAS offers high availability, scalability, and transparency, and fully maintains security, accounting, and application-specific policies. When Cisco WAAS is integrated into the packet network, it provides robust application acceleration and WAN optimization capabilities to facilitate infrastructure consolidation and WAN efficiency.

• WCCPv2, which was originally developed by Cisco Systems®, facilitates the transparent integration of application acceleration technology into the network with high availability and load sharing. The Cisco WAE devices in a given location advertise their availability to the router (or switch, multiple routers, or switches can be used for network path high availability) and specify that TCP traffic should be forwarded to the WAE. When the WAE devices join the service group with the router, the router monitors traffic for flows that should be forwarded to the WAE instead of the original destination. As the WAE begins receiving traffic, it selectively applies optimizations and protocol-level handling based on the configured application policy. With WCCPv2, up to 32 WAEs can join a service group with up to 32 routers, and each receives a portion of the workload that would otherwise traverse the WAN unoptimized. If a WAE fails, surviving members assume the workload of the failed WAE. If all WAE devices fail in a given location, traffic is forwarded across the WAN in an unoptimized fashion until a WAE is recovered.

• PBR is another deployment option available for the Cisco WAAS and the Cisco WAE. With PBR, the network administrator can configure a WAE or multiple WAEs as a next-hop router for all or specific TCP traffic. As the router receives TCP traffic, it forwards the traffic to the WAE as the next-hop router, where optimizations are applied based on the configured application policy. Like WCCPv2, PBR provides transparent integration into the packet network, and also offers high availability to the remote office or data center by using another WAE defined as a next hop if a WAE fails. If all WAEs fail, the policy-based route is considered unavailable, and traffic is forwarded across the WAN in an unoptimized fashion until a WAE is recovered.

• Physical inline is a deployment option that can be leveraged when out-of-path interception and redirection mechanisms are not possible. Cisco WAEs can be configured with an optional 4-port Gigabit Ethernet adapter that provides fail-to-wire capabilities. With this card, Cisco WAAS can be deployed on WAEs that are physically in-path between two network elements (for instance, the switch and the router, or the switch and the firewall). With fail-to-wire capabilities, should a hardware, software, or power issue be presented, mechanical relays in the card automatically fail to a pass-through condition. This allows Cisco WAAS to be deployed in such a way that a disruption would not create a network outage scenario should a problem be encountered.

When the WAE is introduced to the packet network, it can begin applying network and application optimizations based on application policy. For applications in which an explicit application adapter is present, application layer messaging can be terminated locally to mitigate latency and unnecessary data transfer. For any TCP traffic that must traverse the WAN, the WAE nonintrusively marks the packets such that when received by a distant WAE (through WCCPv2 or PBR), the two WAEs can identify one another and establish peering, negotiate optimization capabilities, and ultimately begin applying optimizations to the traffic that must traverse the WAN.

Device Autodiscovery

Cisco WAAS integrates transparently with the packet network and also automatically discovers all Cisco WAE devices in the path between a source and destination pair. As each TCP connection is established, Cisco WAAS nonintrusively applies markings to the connection request packets to identify each Cisco WAE in the path between the communicating nodes, as well as which optimizations are being requested based on the configured policy. As marked packets are received by distant Cisco WAEs, the WAE topology is learned and optimization capabilities can then be negotiated (Figure 3).

Figure 3. Cisco WAAS Auto Discovery Process-Requestor

When the receiving node responds to the connection request, the WAE near the receiver sees that the connection response packet is for a connection that is awaiting optimization. The WAE near the receiver then applies optimization acknowledgement markings to the connection response packets. The packets are then returned to the network for delivery to the requestor. As the packets reach the network on which the requestor is located, the packets are redirected to the nearby WAE, and the WAE then understands the optimization capabilities of the other WAE in the path. At this point, both WAEs are fully aware of one another, and can start applying optimizations. Figure 4 shows the receiver side of the auto-discovery process.

Figure 4. Cisco WAAS Auto Discovery Process-Receiver

The Cisco WAE always leaves the optimization markings in the connection packets to enable support for environments in which multiple Cisco WAEs may be in the path between source and destination, allowing for topologies such as full mesh, partial mesh, ring, star, and others. Optimization establishment always occurs between the two most distant Cisco WAE devices, even if multiple Cisco WAEs are in the path. Any intermediary WAEs automatically pass the connection through unoptimized, allowing the outermost WAEs to handle optimization of the flow. With Cisco WAAS automatic discovery, administrators don't need to configure complex and tedious overlay networks-which introduce the chance of human error and could even defeat the underlying network topology.

Cisco WAAS TFO

When Cisco WAE devices discover each other during the client-server connection establishment, multiple optimizations can then be applied based on the configured application traffic policy, which is discussed later in this document. One such optimization is Cisco WAAS TFO. With TFO, Cisco WAAS can help applications overcome limitations caused by the WAN and underpowered client or server TCP stacks. Cisco WAAS TFO employs a robust TCP proxy to safely optimize TCP at the WAE device by applying TCP-compliant optimizations to shield the clients and servers from poor TCP behavior due to WAN conditions. Cisco WAAS TFO improves throughput and reliability for clients and servers in WAN environments:

• Large initial windows-Cisco WAAS increases the initial TCP window after autodiscovery to help TCP connections more quickly exit slow-start so that WAN bandwidth can be used more quickly, providing performance improvement for not only short-lived connections that are normally starved for bandwidth, but also longer-lived connections that are forced to reenter slow-start because of congestion.

• Window scaling-Cisco WAAS allows devices using standard TCP implementations to enjoy the benefits of window scaling without client or server modification. Employing window scaling allows Cisco WAAS to drastically improve performance over LFNs, or networks that have high bandwidth and high delay characteristics. By safely scaling TCP windows, Cisco WAAS helps applications that would normally be throughput-constrained to perform well in WAN environments and take full advantage of the available capacity provided by the WAN.

• Advanced congestion management and loss recovery-Cisco WAAS uses advanced congestion-management and loss-recovery techniques to help ensure that maximum throughput is safely restored after scenarios in which packet loss is encountered. Cisco WAAS advanced congestion management not only helps improve overall throughput, but also maintains compatibility with other TCP implementations (including standard TCP implementations) that may be in use on the network.

Figure 5 shows how Cisco WAAS TFO shields clients and servers form WAN conditions. TFO provides significant performance improvement and stability for clients and servers, because standard operating system TCP stacks were not designed to operate in WAN environments.

Figure 5. Cisco WAAS TFO Improves Application Performance and Reliability

Advanced Network Compression

Cisco WAAS employs advanced network compression to minimize the amount of data that must be transferred per connection. Cisco WAAS advanced network compression is built from two unique compression types that can work independently or in conjunction with each other.

DRE is an advanced form of network compression that allows Cisco WAAS to maintain an application-independent history of previously seen data from TCP byte streams. This information is then used to remove redundant patterns of data found in future or current transmissions, enabling significant levels of compression for redundant traffic patterns, and also ensuring message and application coherency because the original message is always rebuilt and verified by the distant WAE. Because DRE operates within the context of the transport protocol and is bidirectional, it is application-independent, and it is effective regardless of the direction of traffic flow. Therefore, data patterns that are identified for one application protocol can be used by other applications, and patterns that are identified for one direction of traffic flow can be used to remove redundancy for traffic flowing in a different direction. With DRE, a user can access information through one protocol or application and receive significant compression when accessing the same or similar information through a different protocol or application.

Figure 6 shows the advanced compression of Cisco WAAS using DRE and LZ compression:

Figure 6. Cisco WAAS Advanced Compression

DRE and persistent LZ compression, coupled with TFO can provide an exponential improvement in throughput and performance. TFO provides facilities to overcome WAN conditions and achieve better utilization of existing WAN capacity, and can do so even with the small data signatures generated through the process of DRE's powerful redundancy elimination engine. With Cisco WAAS, available WAN capacity is used more efficiently, and more data can be transferred using less network capacity.

Application Traffic Policy Engine

Cisco WAAS gives administrators the flexibility they need to define how the Cisco WAE should handle specific traffic types. Such definitions include optimizations (DRE, LZ compression, and flow optimizations), monitor, and bypass. By default, more than 25 application types are identified and more than 150 application classifiers are provided, each mapped to a specific set of optimizations to provide the most throughput improvement for that specific application. Table 1 shows the application types identified in the default configuration.

Table 1. Default Cisco WAAS Application Policy: Common Application Types Optimized by Cisco WAAS

Authentication	Backup	Call management	Conferencing
Console	Content management	Directory services	Enterprise applications
Enterprise messaging	File services	File transfer	Instant messaging
Name services	Network analysis	Printing	Remote desktop
Replication software	Database	Remote access	Storage protocols
Streaming	Systems management	Version management	Intranet and Internet

Industry-Leading Wide Area File Services

Because Cisco WAAS is built using modular software architecture, many layers of optimizations are built into a single software platform. Cisco WAAS offers a powerful and flexible WAN optimization solution and also additional acceleration for specific protocols that need assistance, such as the Common Internet File System (CIFS) protocol for Windows file sharing environments. Cisco WAAS file services optimizations are built using components from the industry-leading WAFS capabilities provided in the Cisco WAFS Software Release 3.0.

Cisco WAAS file services capabilities integrate transparently not only into the packet network, but also into the logical network. No client or server software installation is required to take advantage of the file services optimizations offered by Cisco WAAS. Cisco WAAS provides the following WAFS capabilities:

• Protocol-specific acceleration-Cisco WAAS supports all CIFS clients and dialects, and examines client-server communications on a message-by-message basis to fully understand the operations being performed. As such, Cisco WAAS can make intelligent decisions on how to most appropriately accelerate specific operations. Such acceleration can include read ahead, message and operation batching, multiplexing, or pipelining. In many cases Cisco WAAS can safely handle message traffic locally without compromising protocol correctness or data integrity, thereby providing LAN-like performance. In cases in which messages must traverse the WAN without modification to maintain correctness, coherency, security, or data integrity, Cisco WAAS transfers them using the underlying network optimizations, including TFO, DRE, and persistent LZ compression. With protocol-specific acceleration, Cisco WAAS provides LAN-like performance for remote users accessing centralized file server storage without compromising protocol semantics, coherency, or correctness. Furthermore, Cisco WAAS safe acceleration for file services protocols work in environments with global collaboration, including CAD/CAM, software development, and databases through global file locking, because file lock requests always propagate to the origin server.

• Investment protection-Cisco WAAS is built with a future-proof architecture such that should protocols change, Cisco WAAS can still safely apply acceleration. Cisco is a member of relevant partner programs with companies that develop the CIFS protocol to ensure timely improvement to Cisco WAAS to ensure support for future versions of the CIFS protocol.

• Safe Data and metadata caching-Along with protocol-specific acceleration, Cisco WAAS can also cache data and metadata when safe. By employing an application-specific data and metadata cache, Cisco WAAS can serve usable content, once validated for coherency, to the requesting user. For scenarios in which an object is cached but has been modified, Cisco WAAS can fetch the updated contents using network optimizations such as TFO, DRE, and persistent LZ compression. Under no circumstances can Cisco WAAS serve outdated or changed content, as the origin server owns the authoritative copy of files and also the state of each file, including file locks.

• Centralized file storage-Cisco WAAS allows IT to centralize distributed file servers, storage capacity, and data into the data center where IT staff is readily available. Centralizing distributed servers and storage has many tangible benefits, including:

–Fewer devices to manage-Cisco WAAS can effectively replace the need for distributed file servers, minimizing the number of devices to manage in the infrastructure and eliminating many costly components, including servers, server operating systems and maintenance, OS patching and hotfixes, antivirus, tape drives and libraries, tape cartridges, backup software, and more.

–Taking advantage of existing data center infrastructure-With a consolidated infrastructure, application and file servers can use the data center infrastructure components to full potential, including server virtualization and storage virtualization. With protocol-specific acceleration, most of the workload is handled at the edge by Cisco WAAS, thereby enabling greater economies of scale with existing server and storage infrastructure.

–Fewer points of data protection-By consolidating distributed file server storage and data into the data center, fewer copies of data must be protected, thereby helping control the cost of protecting data and maintaining compliance with federal or industry regulation.

–Streamlined disaster recovery and business continuity-Cisco WAAS facilitates consolidation and minimizes the amount of application and file storage infrastructure necessary to support a distributed enterprise. Fewer remote application instances and fewer copies of data significantly simplifies disaster recovery and business continuity planning, deployment, and management.

• Data integrity, correctness, and coherency-Cisco WAAS accelerates protocols only when it is safe. Critical messages, including authentication, authorization, file lock requests, and write requests, always propagate to the data center without modification by Cisco WAAS and can take advantage of the underlying WAN optimization framework provided through DRE, TFO, and persistent LZ compression. With Cisco WAAS, the data center file server or NAS device always owns the data itself, the state of the data, and any locks applied against the data. Therefore, when a user closes a file and exits the application, the data is safely stored in the data center.

• Integration with advanced network compression-Cisco WAAS takes advantage of the advanced compression layers provided by DRE and persistent LZ compression. By integrating with DRE and persistent LZ compression, Cisco WAAS dramatically minimizes the amount of bandwidth consumed by application messaging and data transfer to the amount of changed data. This feature is extremely helpful in cases in which messages must traverse the WAN or when file data is being written back to the file server unmodified or partially modified.

• Disconnected mode of operation-Cisco WAAS application acceleration also provides a read-only disconnected mode of operation for situations in which the WAN or the file server has gone offline for an extended period of time. For information that needs to be accessible during periods of disconnection, Cisco WAAS aggressively caches files, folders, metadata information, and access control information. During periods of disconnection, a nearby domain controller can be used to authenticate users and the WAE can validate that requesting users are authorized to access cached data in a read-only fashion.

Summary

IT faces significant pressure to do more with less: higher application and data availability, higher levels of performance and throughput, fewer people, fewer devices, and less time. Application-delivery technologies help IT organizations consolidate application infrastructure from distributed sites into the data center while providing optimizations necessary to improve application and data access performance over the WAN. Cisco WAAS provides robust optimizations for the network and specifically for applications to help IT improve delivery of applications and application data to the enterprise edge while minimizing infrastructure requirements.

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Small & Medium Business Data Center

Cisco Wide Area Application Services (WAAS) V4.0 Technical Overview