All about Windows 7 BranchCache

Now a days transfer of Application and data access over WAN is slow in Branch Offices. By this nature of slow connection which results the dissatisfaction of  user and on their productivity though improving network performance is expensive and difficult to implement.

The Windows 7 and Windows Server 2008 R2 operating systems introduce BranchCache, which enables content from file and Web servers on a wide area network (WAN) to be cached on computers at a local branch office. It not only speeds up access to data and documents from Web and file servers by reducing web and file access over a WAN link, it frees up bandwidth over the WAN link for other uses.

BranchCach has two operating modes:

• Hosted Cache mode
• Distributed Cache mode.

Hosted Cache mode specifies a local server for caching content downloaded form a content server over the WAN. Caching occurs at the very first request from a user in a branch office. A user from the same branch office subsequently requests for the same content will establish a connection with and retrieve the cached content from the local Hosted Cache server. Host Cache mode is recommended for a branch with more than 50 clients and does require some form of infrastructure for caching and accessing the content in a local server.

Distributed Cache mode, on the other hand, is for a small branch without a local file server that can be used as a hosted cache server. This configuration caches content downloaded from a content server over the WAN at a user’s computer. Caching occurs at the very first request from a user in a branch office. A user from the same branch office subsequently requests for the same content will locate the cached content by broadcasting, and then retrieve the content from that user’s computer in the local area network. Peer-to-peer sharing is the basic idea. There is no central repository in the branch. There are no requirements for servers or services in the branch office beyond client computers running Windows 7.

This is how the BranchCache™ process works:

1. A Windows 7 client connects to the content server in the central office and requests a file (or file segment) exactly as it would if it were retrieving the file without using BranchCache™.
2. The content server authenticates and authorizes the client exactly as it would without BranchCache™. If successful, it returns content metadata over the same channel that data would normally have been sent. If this is the first time any client from the branch office network is requesting a file not already cached on the local network, the client retrieves the file directly from the content server.
3. In Distributed Cache mode, the client sends a request on the local network for the required file by using the Web Services Discovery (WS-Discovery) multicast protocol. The segment hashes provide a unit of discovery. This helps reduce the total number of lookups performed for a given piece of content (versus looking up each block). The client that previously cached the file sends the file to the requesting client. The data is encrypted using a key derived from the hashes sent by the content server, as part of the content metadata. The client decrypts the data, computes the hashes on the blocks received from the first client, and ensures that it is identical to the block hashes provided as part of the content metadata by the content server. This ensures that the content has not been modified.

While in Hosted Cache mode, the client uses the hashes in the metadata to search for the file in the Hosted Cache server. A key difference in Hosted Cache mode is that a client establishes an SSL connection with the Hosted Cache server, and it offers content identifiers over this encrypted channel. The Hosted Cache server connects to the client and retrieves the set of blocks that are not cached.

To implement BranchCache, client computers must be running Windows® 7, with the BranchCache feature enabled. Web servers and file servers must be running Windows Server 2008 R2, with the BranchCache feature enabled

Useful Links :

Download

• BranchCache Executive Overview (.doc)
• BranchCache Technical Overview (.doc)
• BranchCache Security Guide (.doc)

• BranchCache Deployment Guide
• BranchCache Migration Guide

Video guide

• Remote Connectivity in Windows 7 (Snack)
• Windows 7 Enterprise Demo of BranchCache