Specifications

Network Requirements and Preparation
Planning and Installation Guide 9 – 19
Time Services
When IP phones are used, time services must be available to maintain the telephone’s
date and time display. This requires a server that supports the Simple Network Time
Protocol (SNTP). In addition, you must configure your DHCP server to provide the
correct GMT offset to the IP phones at each site.
Virtual Private Network (VPN)
With the increasing desire to leverage the public Internet, and the concern about
security, IP VPNs (Internet Protocol Virtual Private Networks) are becoming the secure
access of choice. IP VPNs establish secure communications between employees,
branches, or partners by using strong IP-based encryption and authentication
techniques for transport security over the public Internet.
IP VPNs are typically viewed as falling into three major categories: remote access VPNs,
intranets (company site-to-site), and extranets (business-to-business). These services
are being adopted by companies of all sizes as a result of the powerful combination of
high-speed access links and public networks. An example is the use of high-speed, low-
cost broadband DSL connectivity to enable teleworkers or branch offices to link
securely with the company network via the Internet, as if they were accessing the LAN
at the office including all network applications. A sample VPN configuration is shown
in Figure 9-1.
Figure 9-1 VPN Topology
IP VPNs can be provided via hardware or software solutions located at the remote
facility (branch office or teleworker’s home) and the customer premises. These devices
or solutions use technologies such as tunneling, encryption, and authentication to
guarantee secure communications across a public infrastructure.
All the components of your ShoreTel 6.1 system must exist in the same enterprise
private network. VPNs can be used to bridge your private network across the Internet
so that the networks for two buildings are both part of the same private network. For
multiple locations that share a private network, bandwidth calculations should include
the effective bandwidth inside the private network, rather than the raw bandwidth.