The Optimization Policy applies various compression and acceleration techniques to improve the performance of applications across the WAN.
Note 
If a flow is not directed to a tunnel, it’s not subject to the Optimization Policy.
If a flow is not directed to a tunnel, it’s not subject to the Optimization Policy.
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All Silver Peak appliances are equipped with Network Memory™ technology. Network Memory inspects all inbound and outbound WAN traffic in real-time and stores a single local instance on each appliance.
Before sending information across the WAN, appliances use Network Memory to compare real-time traffic streams to the stored patterns. If a match exists, a short reference pointer is sent to the remote Silver Peak appliance, instructing it to deliver the traffic pattern from its local instance. Repetitive data is never sent across the WAN.
If content is modified, the Silver Peak appliance detects the change at the byte level and updates the network’s “memory”. Only the modifications are sent across the WAN. At the destination, Silver Peak appliances combines these with the original content.
Even when the file is not identical to the version that was previously downloaded, significant performance improvements are realized by transporting only the incremental changes across the WAN.
If a web application is generating dynamic pages (for example, using HTTP), only delta information is transferred. For example, a SharePoint table with many rows updates by just transmitting the delta for the row, rather than the whole page.
If several employees in an office chose to watch the same video (for example, a distance learning module or a taped CEO address), Network Memory eliminates the need to send multiple copies across the WAN. This has the same advantage whether they’re watching the video simultaneously, or at different times.
If employees in an office need to download the same software patch, Network Memory eliminates the need to send multiple copies across the WAN.
Once the first backup is completed, future “full” backups are effectively reduced to “incremental backups” as far as WAN traffic is concerned.
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Optimizes for maximum data reduction at the potential cost of slightly lower throughput and/or some increase in latency. It is appropriate for bulk data transfers such as file transfers and FTP, where bandwidth savings are the primary concern.
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Ensures that Network Memory processing adds no latency. This may come at the cost of lower data reduction. This is appropriate for extremely latency-sensitive interactive or transactional traffic. It's also appropriate when the primary objective is to fully utilize the WAN pipe to increase the LAN-side throughput, as opposed to conserving WAN bandwidth.
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This is the default setting. It dynamically balances latency and data reduction objectives and is the best choice for most traffic types.
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Compression reduces the bandwidth consumed by traffic traversing the WAN. Payload compression uses algorithms to identify relatively short byte sequences that are repeated frequently over time. These sequences are then replaced with shorter segments of code to reduce the size of transmitted data. Simple algorithms can find repeated bytes within a single packet; more sophisticated algorithms can find duplication across packets and even across flows.
IP header compression provides additional bandwidth gains by reducing packet header information using specialized compression algorithms.
Silver Peak appliances include state of the art, cross-flow data compression and header compression as part of a broader Local Instance Networking solution. Information gleaned from the compression of one flow can be applied to other flows.
TCP acceleration uses techniques such as selective acknowledgement, window scaling, and message segment size adjustment to compensate for poor performance on high latency links.
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CAUTION 
Because changing these settings can affect service, Silver Peak recommends that you do not modify these without direction from Customer Support.
Because changing these settings can affect service, Silver Peak recommends that you do not modify these without direction from Customer Support. |
Limits the TCP MSS (Maximum Segment Size) advertised by the end hosts in the SYN segment to a value derived from the Tunnel MTU (Maximum Transmission Unit). That is,
Tunnel MSS = Tunnel MTU – Tunnel Packet Overhead.
This feature is enabled by default so that the maximum value of the end host MSS is always coupled to the Tunnel MSS. If the end host MSS is smaller than the tunnel MSS, then the former is used instead.
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Preserves the packet boundaries end to end. If this feature is disabled, then the appliances in the path could coalesce consecutive packets of a flow to utilize bandwidth more efficiently.
It is enabled by default so applications that require the matching packet boundaries don’t fail.
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Enable Silver Peak TCP SYN Option Exchange
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Controls whether or not Silver Peak forwards its proprietary TCP SYN option on the LAN side. Enabled by default, this feature detects if there are more than two Silver Peak appliances in the flow’s data path and optimizes accordingly.
It needs to be disabled if there is a LAN–side firewall or a third-party appliance that would drop a SYN packet when it sees an unfamiliar TCP option.
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Tries to override asymmetric route policy settings. It emulates Auto-opt behavior by using the same tunnel for the returning SYN+ACK as it did for the original SYN packet.
Enabled by default, this feature needs to be disabled if the asymmetric route policy setting is necessary to correctly route packets. In such a case, other features like flow redirection might need to be employed to ensure TCP optimization of the flow.
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NOTE: Whether this feature is enabled or not, the default behavior when a tunnel goes Down is to automatically reset the flows.
If enabled, it resets all TCP flows that are not accelerated but should be (based on policy and on internal criteria like Tunnel Up event).
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This is the WAN–side TCP Window scale factor that Silver Peak uses internally for its WAN–side traffic. This is independent of the WAN–side factor advertised by the end hosts.
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Resets all flows that are consuming a disproportionate amount of buffer and have a very slow throughput on the LAN side. These flows affect the performance of all other flows and as such no flows see improvement in throughput through TCP acceleration due to a few slower end hosts or a lossy LAN. By default, it is enabled and the number relates indirectly to the amount of time the system waits before resetting such slow flows.
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This is the default setting. This mode offers optimized performance in almost all scenarios.
In some unique cases it may be necessary to downgrade to Standard performance to better interoperate with other flows on the WAN link.
Provides aggressive performance and should be used with caution. Recommended mostly for Data Replication scenarios.
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This setting clamps the maximum buffer space that can be allocated to a flow, in each direction.
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Protocol-specific acceleration techniques can help minimize latency and improve application response times. The Optimization Map provides configurable protocol acceleration explicitly for CIFS, SRDF, SSL, and Citrix:
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Each Optimization Map includes the default SSL and CIFS ports as “built-in” entries. You can edit or delete these entries.
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CIFS acceleration includes read-aheads, write-behinds, and metadata caching. This reduces the impact of latency on data transfers that use this protocol. CIFS is enabled for ports 139 and 445.
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When you install SSL certificates into Appliance Manager, you’re able to securely decrypt the traffic, optimize it, and re-encrypt the deduped traffic. SSL is enabled for port 443.
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Because SRDF doesn’t use a reserved port, SRDF optimization is disabled by default. If SRDF optimization were run on non-SRDF traffic, it would corrupt the data. So, be sure that the port you associate with this optimization is actually running SRDF traffic.
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The version of Citrix used determines which port(s) to use for Citrix optimization. For a list of Citrix ports, you can check the Configuration - Built-in Applications page.
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In a network environment, it’s possible that all appliances don’t have the same protocol-specific optimization configurations. Hence, the side that initiates the flow determines the protocol-specific optimization.
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Current Flows > Details on the receiving (server) side will indicate if the remote peer has overridden the policy.
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