Policy-based multi-path Wan

Policy-based multi-path Wan

The construction of a multi-path Wan can reduce business continuity risks, while avoiding the high cost of building a dedicated-Line Wan and a dedicated-Line Wan. Therefore, enterprises can make full use of cheap and abundant DSL Internet links while effectively utilizing existing WAN resources.

The enterprise's reliance on Wan is reaching a record level. Remote access to key business applications grows steadily as enterprises continue to integrate data centers. However, these enterprises and Web applications were initially designed for high-speed LAN, and remote employees never satisfied Wan bandwidth when accessing these applications, this results in unpredictable network performance and user frustration. Enterprises are also seeking to deploy new applications such as VoIP. VoIP can save considerable cost for users, but it is highly sensitive to the latency of the wide area network. In addition, frequent remote backup and replication required by business continuity puts further pressure on the over-utilized Wan.

When users try to break through the dual constraint of higher latency caused by wide area network bandwidth and geographical distance, the third factor is: reduce the risk of single link dependency between different locations. Creating a fully redundant Wan in all locations is rarely an option. On the contrary, users are now building public/private hybrid Wan, which can better ensure business development and reduce costs.

Build a multi-path Wan

Traditionally, users rely on secure, verified, and predictable leased lines to connect to remote sites. But the price for this sense of security is limited bandwidth, high costs, and long periods of inflexible circuit services. DSL Internet connections provide robust bandwidth, attractive prices, and rapid service delivery, but the reliability problem has always hindered widespread deployment.

The policy-based multi-path technology enables users to use public Internet and private Wide Area Networks for key business applications in a reliable, predictable, and cost-effective manner. You can now select which applications are running on which wide-area network cable according to the application-based business policy. If a Wan line is unavailable or cannot meet the required performance requirements, the policy-based multi-path technology automatically and transparently transfers the application transmission stream to other available WAN links, ensure that the application transmission stream continues to be transmitted effectively and reliably.

Reduces the risk of line migration

Policy-based multi-path technology allows users to use low-cost Wan transmission technology (such as DSL Internet for key business transmission streams) with time-tested leased lines. You can use all available bandwidth to evaluate the impact on Application quality when migrating to a cheap Internet. Policy-based multi-path technology can be used in a variety of Wan transmission technologies, including OC-3, T-1, frame relay, DSL, satellite, ISDN and other technologies.

With the help of policy-based multi-path technology, you can confidently deploy applications on public Internet connections, such as email, Web, and storage replication, because these applications are very important but not sensitive to latency. The result is that the bandwidth on the more expensive leased line is released so that they can be used for latency-sensitive applications such as SAP, Oracle, and Citrix interactive applications or VoIP. In addition, all data streams transmitted over the Internet are encrypted securely.

At the same time, the use of leased lines and Internet connections can greatly improve the overall availability of enterprise wide area networks. Frame Relay has a reliability of 99.99%, while Internet connections lack inherent reliability. By constructing a dedicated/public hybrid Wan, the overall reliability and availability of the network are superior to those of a dedicated or public WAN.

Business policy provision

Enterprises have a variety of applications, which have different bandwidth requirements and have different tolerance for latency. They use the same Wan. Highly Interactive applications such as Citrix, SAP, and Oracle must respond to users in a timely manner while maintaining low bandwidth consumption. applications such as email, FTP file transfer, and storage replication consume a large amount of bandwidth, however, there is no latency problem. However, VoIP is still highly sensitive to the latency and jitter of wide-area networks.

When using policy-based multi-path technology, it is very easy to determine which applications are running on which wide-area network link. You only need to set application-based business policies. Users define bandwidth, latency, and packet loss policies for each application type. If the performance of a wide-area network link drops to the default limit, you can immediately and transparently switch the application transmission stream to another wide-area network cable without interrupting user sessions and service quality policies.

IT staff can easily set fine-grained Performance Parameters for Policy-based multi-path. For example, you can set a business policy to specify that if the delay on the DSL link lasts for more than 200 milliseconds for 3 minutes, the SAP and Citrix transmission streams will be switched from the DSL Internet link to the frame relay line. When the link performance is restored, the application transmission stream can dynamically switch from frame relay to the DSL Internet link according to the application-based business policies.

When the transmission streams are switched to different lines, all existing QoS policies are still executed to ensure that each application continues to obtain their bandwidth resources fairly. For example, you can develop a policy that enables VoIP and SAP applications to run on frame relay lines, while email, Web, and storage replication applications run on DSL lines. However, if the performance on the DSL becomes unacceptable, the application transmission stream will also be transferred to frame relay. The existing Frame Relay QoS policy will continue to be implemented to ensure that VoIP and SAP applications use Wan bandwidth first, while email, Web transmission stream, and storage Replication Use idle bandwidth.

Secure and convenient multi-path

Using the Internet to transmit key business data often brings users a real concern: security. Encryption technology is required to use Internet links to protect data privacy and integrity. IPSec Encryption technology can be used to ensure reliable security, so as to avoid unnecessary deployment and management of additional devices in remote locations. You can also use an existing IPSec VPN dedicated device in the network.

It is intuitive to create business policies for Policy-based multi-path technology: Use the following three policies to define different application classes and allocate applications to these application classes, set QoS behavior for each application class.

1. Always select the specified path. For example, the company's core financial and Customer Relationship applications can be set to run on the frame relay link.

2. Switch only when the link fails. Email and Web transmission streams running on DSL can be switched to frame relay only when the Internet link is completely interrupted.

3. Switch when Performance drops. The performance limits of each path can be defined, so that application transmission streams can be transferred to different lines only when the specified link performance threshold is exceeded. For example, the email and Web transmission streams are transmitted over the Internet link until the delay exceeds a certain threshold value, and then transferred to the T1 line. ■

Three real Deployment Scenarios

Policy-based multi-path technology can be deployed in different ways, allowing users to make full use of existing and new WAN link resources.

1. Private/Public hybrid network: Frame Relay and DSL Internet

Many users continue to rely on expensive leased lines, while policy-based multi-path technology provides the ability to transmit business transmission streams over the Internet, while reducing risks. Key business or latency-sensitive applications such as SAP, Citrix, and VoIP transmission streams are transmitted over frame relay, while important but not-sensitive transmission streams (such as Web, email, and storage replication) encrypted and securely transmitted over a public Internet connection.

2. Public/Private Network: Two DSL links

The policy-based multi-path technology can be used for multiple DSL Internet links. For example, if a leased line takes a long time to provide or the purchase costs are too high, you can deploy a high-elastic Wan immediately, assign bandwidth to the transmission stream as needed.

3. Dedicated/public networks: Frame Relay and SATELLITE LINES

Satellite lines still play a key role in enterprises with broad geographic maps, but they provide extremely limited bandwidth. Users can now migrate their satellite links to frame relay or DSL. Policy-based multi-path technology reduces the need to increase the cost of expensive satellite links by applying existing Frame Relay and satellite links to produce transmission streams, enable enterprises to make full use of their investments in these two technologies.

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Article entry: csh responsible editor: csh