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A branch office, commonly referred to as a remote site, uses WAN connections to a central site or to other remote sites. The remote site typically has fewer users than the central site, and so needs a smaller-size WAN connection.
Because remote-site traffic is typically sporadic, the network designer must determine whether it is more cost-effective to offer a permanent or dialup solution.
Telecommuters may also require access to the remote site through a different media. Therefore, the remote site must have a mix of equipment, but typically not as much as the central site. Typical WAN solutions for remote site to central site connections are:
- Leased line
- Frame Relay
- X.25
- ISDN
- XDSL (digital
subscriber line) -- This
technology enables delivery of high-speed data, voice, and
multimedia over conventional telephone wires.
Typical considerations for a remote-site WAN
connection follow:
- Multiple access connections
-- Multiple users connect to the central site by using different
media. Therefore, branch-office site considerations must include
various media options and support for simultaneous access from
multiple users.
- Cost -- Keep the costs low
while maintaining an adequate level of service. For example,
because some WAN charges, such as ISDN, are based on usage, it
is important that companies have a solution that can implement
features that will optimize bandwidth and minimize WAN costs. Features such as DDR and compression ensure that WAN costs are
kept to a minimum. In another example, because leased lines are
generally charged on a fixed basis, you may want to consider
this service only if the line can sustain a certain link
utilization level.
- Access control -- Company
information must be restricted, allowing users access only to
areas in the network that they are authorized to access. For
example, access lists can filter out unauthorized data flow
between offices and PPP network links, whereas PAP and CHAP can
identify the remote entity to prevent unauthorized network
connections.
- Quality of service -- It is
important to prioritize traffic over the link and manage traffic
flow so that bursty traffic does not slow mission-critical
traffic.
- Redundancy and backup --
Because a link may fail or high link utilization may occur at
certain peak usage times during the day, it is important to back
up the connection to the central office. Avoid using backup
links provided by the same service vendor that provides the
primary links.
- Authentication -- The
remote site must be able to authenticate itself to the central
site.
- Availability -- Service
providers may not offer certain WAN services in some regions.
This consideration generally becomes critical as sites are
set up in more remote locations.
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