SteelHead™ Deployment Guide : Optimization Techniques and Design Fundamentals : Choosing the Right SteelHead Model
  
Choosing the Right SteelHead Model
Generally, you select a SteelHead model based on the number of users, the bandwidth requirements, and the applications used at the deployment site. However:
  • If you do not want to optimize applications that transfer large amounts of data (for example, WAN-based backup or restore operations, system image, or update distribution), choose your SteelHead model based on the amount of bandwidth and number of concurrent connections at your site.
  • If you want to optimize applications that transfer large amounts of data, choose your SteelHead model based on the amount of bandwidth, the number of concurrent connections at your site, and the size of the RiOS data store.
  • If you want to use SteelHead to enforce network Quality of Service (QoS), make sure to consider the SteelHead model QoS bandwidth in addition to the optimization criteria you need.
    • You can also consider high availability, redundancy, data protection, or other design-related requirements when you select a SteelHead. SteelHead models vary according to the following attributes:
  • Optimized WAN bandwidth license limit
  • Maximum number of concurrent TCP connections that can be optimized
  • Maximum number of possible in-path interfaces
  • Availability of RAID and solid-state drives (SSD) for the RiOS data store
  • Availability of fiber interfaces
  • Availability of redundant power supplies
  • Availability of hardware-based compression card
  • Availability of VSP
  • Upgrade options through software licenses
    • All SteelHead models have the following specifications that are used to determine the amount of traffic that a single SteelHead can optimize:
  • Number of concurrent TCP connections - Each SteelHead model can optimize a certain number of concurrent TCP connections.
    • The number of TCP concurrent connections that you need for optimization depends on the number of users at your site, the applications that you use, and whether you want to optimize all applications or just a few of them. When planning corporate enterprise deployments, Riverbed recommends that you use ratios of 5 to 15 concurrent connections per user if full optimization is desired, depending on the applications being used.
    If the number of connections that you want to optimize exceed the limit of the SteelHead model, the excess connections are passed through unoptimized by the SteelHead.
    The TCP protocol only supports approximately 64,000 ports per IP address for outbound or inbound connections to or from a unique IP-Port pair. If your design or environment requires you to support more than 64,000 concurrent connections to a single IP address for optimization, Riverbed recommends that you use multiple in-path interfaces or service port mapping.
    For more information about service port mapping, go to https://supportkb.riverbed.com/support/index?page=content&id=S:S16309&actp=search.
  • Number of encrypted TCP connections - The SteelHead transparently optimizes encrypted connections by first decrypting it to optimize the payload, and then reencrypting it for secure transport over the WAN. Examples of encrypted applications and protocols that a SteelHead can optimize include HTTP Secure (or HTTPS/SSL) and Microsoft Outlook/Outlook Anywhere traffic (or encrypted-MAPI, RPC-over-HTTPS).
    • If you have predominately encrypted connections, contact your Riverbed account team for assistance with determining the appropriate model.
  • WAN bandwidth limit - Each SteelHead model has a limit on the rate at which it sends optimized traffic toward the WAN. You might not need a SteelHead model that is rated for the same bandwidth available at the deployment site; however, Riverbed recommends that you make sure that the selected appliance is not a bottleneck for the outbound optimized traffic. The optimized WAN bandwidth limit applies only to optimized traffic.
    • When a SteelHead reaches its optimized WAN bandwidth limit, it begins shaping optimized traffic along this limit. New connections continue to be optimized as long as the concurrent TCP connection count is not exceeded. The optimized WAN bandwidth limit is not to be confused with the QoS WAN bandwidth limit that applies to both optimized and pass-through traffic.
  • RiOS data store size - Each SteelHead model has a fixed amount of disk space available for RiOS SDR. Because SDR stores unique patterns of data, the amount of data store space needed by a deployed SteelHead differs from the amount needed by applications or file servers. For the best optimization possible, the RiOS data store must be large enough to hold all of the commonly accessed data at a site. Old data that is recorded in the RiOS data store might eventually be overwritten by new data, depending on traffic patterns.
    • At sites where applications transfer large amounts of data (for example, WAN-based backup or restore operations, system image, or update distribution), you must not select the SteelHead model based only on the amount of bandwidth and number of concurrent connections at the site, but also on the size of RiOS data store. Sites without these applications are typically sized by considering the bandwidth and number of concurrent connections.
    If your requirements exceed the capacity of a single SteelHead, consider a SteelHead cluster. There are many ways to cluster SteelHeads and scale up the total optimized capacity and provide redundancy.
    For more information about clustering, see In-Path Redundancy and Clustering Examples.
    You need to determine the SteelHead platform best suited for your deployment. SteelHeads are available in the following platforms:
  • Physical - the SteelHead CX, SteelHead DX, and SteelHead EX appliances
  • Virtual - the SteelHead-v for VMware vSphere and Microsoft Hyper-V hypervisors
  • Cloud/SaaS - the SteelHead-c for Amazon Web Services and Microsoft Azure
  • Mobile - the Mobile Controller and the SteelHead Mobile client for Windows and Mac-based laptops
    • The Hyper-V hypervisor platform does not support the Riverbed bypass NIC card.
    The SteelHead CX model is a dedicated WAN optimization solution that supports a rich set of application protocols that includes but is not limited to Microsoft Exchange, CIFS, SMB, SharePoint, HTTP/HTTPS, Lotus Notes, FCIP, SRDF, and SnapMirror.
    The SteelHead DX model is a dedicated WAN optimization solution for data center-to-data center storage and data replication. SteelHead DX supports a limited set of application protocols that is specific to its use case, such as FTP, FCIP, SRDF, and SnapMirror. This model features an in-memory or RAM-based data store and an SDR turbo mode that, when combined, increases the optimization performance and throughput beyond that of the highest SteelHead CX model.
    SteelHead DX does not peer with SteelHead CX and SteelHead EX appliances.
    The SteelHead EX model combines WAN optimization, virtualization, and storage consolidation into a single appliance for the branch office. Virtualization is provided by VSP. VSP is a VMware-based hypervisor built into RiOS. VSP enables you to virtualize and localize multiple branch services such as print, DNS, and DHCP, into a single appliance for the branch office. Storage consolidation is provided by the SteelFusion Edge, a virtual edge service that enables end users in a branch office to access and write to centralized storage in the data center over the WAN at local speeds. SteelFusion Edge is available on the SteelHead EX as a license upgrade option.
    A complete enterprise WAN optimization solution can require the deployment of multiple SteelHead platforms. For example, you have hosted some of your applications in the cloud and you do want to optimize the traffic for these applications. In this deployment you need a physical SteelHead in the data center (client side) and a SteelHead-c in the SaaS vendor cloud (server side).
    You might also like to optimize traffic for your internally hosted business applications between their mobile users and data center. Your mobile users access their data center over the Internet using a VPN. In this deployment you need a SteelHead Mobile client in the mobile user laptop (client-side) and a nonmobile SteelHead on the server-side. In addition, you need to deploy a Mobile Controller in your data center to manage and license your SteelHead Mobile clients.
    If you need help planning, designing, deploying, or operating your SteelHeads, Riverbed offers consulting services directly and through Riverbed authorized partners. For details, contact Riverbed Professional Services by email at email proserve@riverbed.com or go to http://www.riverbed.com/services-training/Services-Training.html.