The WANJet appliance is designed to improve the performance of your networks, reducing the bandwidth consumed when transmitting data. For the WANJet appliance to reduce the bandwidth consumed in data transmission, it processes data on one side and reverses this process on the other. This process requires installing at least two WANJet appliances, one to process data on one side and another to reverse data processing on the other side.
WANJet appliance optimization works by identifying redundancy patterns in input data and replacing those redundant patterns with symbols (encoding). When data arrives at its destination, symbols are replaced with the original patterns (decoding). The WANJet appliance stores a list of all identified redundancy patterns and their equivalent symbols, enabling it to handle both sent and received data at the same time.
The WANJet appliance's compression technology operates at Layer 5, the session layer, of the OSI (Open System Interconnection) reference model. This technology enables the WANJet appliance to recognize the redundancies in data traffic.
Some compression products operate at Layer 3 of the OSI model. They wait until individual application data streams merge before searching for redundancies. Merged data streams yield fewer redundancies than data streams that are not merged, so the Layer 3 approach is less than optimal.
Other compression products operate at Layer 7 of the OSI model, the application layer. These products do a great job for specific applications (such as Telnet and FTP), but other traffic crosses the WAN uncompressed, so overall bandwidth savings are limited.
Operating at Layer 5, as the WANJet appliance does, is more efficient than operating at any other layer in the OSI model. Unlike data compression based on Layer 3, the WANJet appliance compresses data streams before data merge, so it finds and removes more redundancies than Layer 3 methods. Unlike Layer 7 techniques, the WANJet appliance's data reduction technology examines all applications and compresses all traffic types.
F5 Networks' Transparent Data Reduction (TDR) technology dramatically reduces the amount of bandwidth consumed across a WAN link for repeated data transfers. For example, without TDR, a 1 MB file transferred across a WAN link by 100 different users would consume 100 MB of bandwidth. With TDR, the same transfer would consume less than 10 MB of bandwidth. This is a reduction of more than 90% in WAN traffic volume.
With TDR, files are not stored or cached, so data is never out of date and it does not need to be refreshed. Every request for a piece of data is sent to the server that actually has that data (even across the WAN link).
In other words, unlike traditional caching algorithms, requests are never served from a local WANJet appliance without the file actually being sent by the server that has the data. As a result, a user can change the name of a file and still experience the same dramatic reduction with TDR.
The WANJet appliance implements TDR technology as a two-stage compression process to maximize bandwidth savings while minimizing processing latency. The first step of the process, called TDR-2, examines the transmitted data to determine if any part of it has been previously sent. If so, the WANJet appliance replaces the previously transmitted data with references. The second step, called TDR-1, further compresses the data through the use of dictionary-based compression and advanced encoding schemes.
TDR-2 data reduction routines identify and remove all repetitive data patterns on the WAN. As data flows through the two WANJet appliances, each one records the byte patterns and builds a synchronized dictionary. If an identical pattern of bytes traverses the WAN more than once, the WANJet appliance nearest the sender replaces the byte pattern with a reference to it, compressing the data. When the reference reaches the remote WANJet appliance, it replaces the reference with the data, restoring the data to its original format.
Following is an illustrated example of how TDR-2 works.
In Figure 2.1 , Client A requests a file named antivirus.dat.
In Figure 2.2 , the server on which the file is stored returns the antivirus.dat file. WANJetA and WANJetB copy the data to RAM.
In Figure 2.3 , Client B requests the same antivirus.dat file.
In Figure 2.4 , WANJetB compares the antivirus.dat file with the data in its RAM to see if the data has changed, confirming that the data in its RAM is still current.
Finally, in Figure 2.5 , WANJetB sends a message to WANJetA to use the local data instead of resending the file, because the data has not changed. WANJetA sends Client B the antivirus.dat file from its local RAM, saving bandwidth over the WAN.
After TDR-2 has removed all previously transferred byte patterns, the WANJet appliance applies a second level of data reduction routines called TDR-1. While TDR-2 compression focuses on repeat transfer performance, TDR-1 improves first transfer performance by examining smaller repetitive patterns and, at the same time, by adapting to changing networking conditions and application requirements.
During periods of high congestion, TDR-1 increases compression levels to reduce congestion and networking queuing delay. During periods of low congestion, TDR-1 reduces compression levels to minimize compression-induced latency. The adaptive nature of TDR-1 ensures that the appropriate compression strategy is applied without degrading application performance.
TDR-1 compresses the remaining network data through intelligent network and application-aware routines that encode the remaining data in as few bytes as possible, improving performance for WAN users.
The goal of Application QoS (Quality of Service) is to provide better service for specific data flows by raising the priority of a specific type of traffic and limiting the priority of other traffic. Accordingly, Application QoS provides complex networks with a guaranteed level of performance for different applications and traffic types. Your network's data transmission is optimized, providing more control over network resources, and ensuring the delivery of mission-critical data.
Utilizing Application QoS policies enables you to downsize the bandwidth consumed over less important network activities and, at the same time, prioritize important and critical data transfer. This way, your bandwidth is used optimally for the transfer of the data that is most important to you.
In addition, the WANJet appliance provides high quality of service for applications that are sensitive to delays by supporting the Voice over Internet Protocol (VoIP).
See Creating Application QoS policies , located in Chapter 7, for information on how to add, edit, or remove Application QoS policies.
The Type of Service (TOS) feature helps to provide the highest quality of data delivery by prioritizing the delivery of one data stream over another. The WANJet appliance deploys the Type of Service methodologies, giving you control over your data streams. You decide which data stream will get to the receiver first by using the Type of Service feature to assign a priority to data traffic using a specific port.
You can assign TOS priorities from 0 to 7, where 0 is the lowest priority, and 7 is the highest. This means that the data using a specific port is transferred according to its priority. For example, you can decide to give the HTTP traffic the lowest priority while giving the FTP traffic the highest priority. You can also assign the same priority, such as priority 7, to multiple protocols. See Configuring ports and services , located in Chapter 6, for instructions on setting TOS priorities.
Simple Network Management Protocol (SNMP) governs the management and monitoring of network devices. SNMP sends messages to SNMP-compliant servers, where users can retrieve these messages using SNMP-compliant software. SNMP data is stored in a data structure called a Management Information Base (MIB). An SNMP trap provides notification of a significant event (such as a power outage, an error, a fault, or a security violation) that occurred on the network.
The WANJet appliance sends SNMP traps to the SNMP server you specify. The traps you view on the SNMP server are errors for troubleshooting purposes. See WANJet appliance messages and codes, in Appendix A for error codes and descriptions.
The WANJet appliance also stores more detailed SNMP reports that you can access using SNMP-compliant software. For the SNMP-compliant software to access the WANJet appliance, it should authenticate itself using a community string you specify. The machine on which the SNMP-compliant software resides should have access to the SNMP data in the WANJet Web UI. See Granting Web UI access , located in Chapter 5.
Figure 2.6 illustrates the interaction between the WANJet appliance and the SNMP traps.
The Management Information Base (MIB) that stores the SNMP data contains details about the network cards like the network card type, physical address, the card speed, the packets sent and received through each card, the bytes sent and received through each card, and the errors of each card.
In addition, the SNMP reports include detailed information about the WANJet appliance such as total bandwidth saved for sent data and for received data.
For more information about configuring SNMP settings, see Configuring Syslog and SNMP settings , located in Chapter 6.
Remote Monitoring (RMON) is an extension to SNMP that provides comprehensive network monitoring capabilities. It is a network management protocol that monitors different types of data traffic passing through the network. Unlike SNMP, RMON can gather network data from multiple types of MIBs. Thus, RMON provides much richer data about network usage. For RMON to work, network devices, such as hubs and switches, must be designed to support it.
RMON1 is the Remote Network Monitoring MIB that was developed so that network administrators could see the traffic and collect information about remote network segments for troubleshooting and performance monitoring. RMON1 focuses on Layer 1 and Layer 2 of the OSI model.
RMON2 is an extension of RMON1 that includes open, comprehensive network fault diagnosis, planning, and performance-tuning features. In addition, RMON2 includes monitoring of packets on the higher layers of the OSI model, from Layer 3 to Layer 6. Therefore, RMON2 provides data about traffic on all network layers for network and application monitoring.
The WANJet appliance supports RMON2 to help administrators gather and analyze detailed information about network traffic, before or after the WANJet appliance processes it, including:
The WANJet appliance supports the RMON2 groups listed in Table 2.1 .
Provides a way for an RMON2 application to determine a list of protocols for which the WANJet appliance monitors and maintains statistics.
Network Layer Matrix
Stores and retrieves network layer (IP layer) statistics for conversations between pairs of network addresses.
Application Layer Matrix
Stores and retrieves application layer statistics for conversations between pairs of network layer addresses.
System Log (Syslog) protocol provides a way to send event notification messages across IP networks to centralized event message collectors called Syslog servers. Messages are sent at the start or end of a process, or to transmit the current status of a process. The WANJet appliance can send system event messages to the Syslog server you specify. The data log sent by the WANJet appliance includes the sent data, and the received data. In addition, the WANJet appliance can send warning logs to the Syslog server, when necessary.
For more information on how to configure the Syslog settings, see Configuring Syslog and SNMP settings , located in Chapter 6.
Connection Intercept (CI) intercepts and resets connections that were initiated before the WANJet appliance became active on the network. If set, this feature ensures that the WANJet appliance resets then optimizes existing connections. As usual, the WANJet appliance optimizes new connections starting after the appliance is up and running.
You can enable Connection Intercept for specific services or ports when creating optimization policies. For details, see Enabling Connection Intercept , located in Chapter 6.