Riverbed SteelHead 5080, Руководство по установке и настройке

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18 | Product Overview
Overview of the SteelHead
• The management plane requires communication between the SteelHead and the SCC on TCP port
9443 and TCP port 22.
• The control plane between the SteelHead acting as the controller and the SteelHeads acting as
group members is over TCP port 9443.
• Encryption service flows over ESP (IP protocol 50). Or, if the network is public, over UDP port 4500.
Overview of the SteelHead
The causes for slow throughput in WANs are well known: high delay (round-trip time or latency), limited
bandwidth, and chatty application protocols. Large enterprises spend a significant portion of their
information technology budgets on storage and networks, much of it spent to compensate for slow
throughput, by deploying redundant servers and storage, and the required backup equipment.
SteelHeads enable you to consolidate and centralize key IT resources to save money, reduce capital
expenditures, simplify key business processes, and improve productivity.
With the SteelHead, you can solve a range of problems affecting WANs and application performance,
including:
• Insufficient WAN bandwidth
• Inefficient transport protocols in high-latency environments
• Inefficient application protocols in high-latency environments
The Riverbed Optimization System (RiOS) intercepts client-server connections without interfering with
normal client-server interactions, file semantics, or protocols. All client requests are passed through to
the server normally, while relevant traffic is optimized to improve performance.
RiOS uses these optimization techniques:
Data streamlining
SteelHeads and Client Accelerator can reduce WAN bandwidth utilization by 65% to 98% for TCP-based
applications using data streamlining. In addition to traditional techniques like data compression, RiOS
also uses a Riverbed proprietary algorithm called scalable data referencing (SDR). SDR breaks up TCP
data streams into unique data chunks that are stored in the hard disk (RiOS data store) of the device
running RiOS (a SteelHead or Client Accelerator host system). Each data chunk is assigned a unique
integer label (reference
) before it’s sent to a peer RiOS device across the WAN. When the same byte
sequence is seen again in future transmissions from clients or servers, the reference is sent across the
WAN instead of the raw data chunk. The peer RiOS device uses this reference to find the original data
chunk on its RiOS data store, and reconstruct the original TCP data stream.
Transport streamlining
SteelHeads use a generic latency optimization technique called transport streamlining. Transport
streamlining uses a set of standards and proprietary techniques to optimize TCP traffic between
SteelHeads. These techniques:
• ensure that efficient retransmission methods, such as TCP selective acknowledgments, are used.
• negotiate optimal TCP window sizes to minimize the impact of latency on throughput.
• maximize throughput across a wide range of WAN links.